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Investigation of nonresponse bias in NHANES 2
Abstract
Forthofer, R. N. (U. of Texas School of Public Health, Houston, TX 77025). Investigation of nonresponse bias in NHANES II. Am J Epidemiol 1983; 117: 507–15.
In the second National Health and Nutrition Examination Survey (NHANES II), there was a 27% nonresponse rate in the examination phase. This report investigates the potential bias in these data due to this large nonresponse rate. Data from a household and medical history interview are used In the investigation of factors related to examination status. In addition, data from the examined group are compared to data from the 1976 National Health Interview Survey (NHIS). Since there was only a 3.7% nonresponse rate for the 1976 NHIS, proportions calculated from these data represent reasonable estimates of the true population values. Several variables have a significant association with the interview and examination status. However, it appears that the nonresponse and poststratiftcation adjustments performed by the National Center for Health Statistics have removed most of these factors as sources of bias. There Is excellent agreement in the marginal distribution of variables between NHANES II for examined persons and the 1976 NHIS.
... 1978;Davis and Smith 1992;Jay et al. 1993), or that men and wom en are equally likely to participate in surveys (Cobb et al. 1957;DeMaio 1980;Berk 1985;Adams et al. 1990). Ag e is negatively related to survey participation (Mercer and Butler 1967;Goudy 1976;O'Neil 1979;Fitzgerald and Fuller 1982;Forthoffer 1983;Herzog and Rodgers 1988;Jay et al. 1993;Francis and Lankshear 1994), with very elderly people especially unlikely to participate (Cobb et al. 1957;Dunkelberg and Day 1973). ...
... And city dwellers are less likely to participate in surveys than other people (Reuss 1943;Dunkelberg and Day 1973;DeMaio 1980;Fitzgerald and Full er 1982;Smith 1983;Forthoffer 1983;Smith 1984;Jay et al. 1993). On the whole, many factors besides feelings of ethnic identity may cause people to fail to respond to the tribal identification item. ...
... Surveys and follow-up studies conducted over the last 30 years have tended to have low participation rates. [1][2][3][4][5][6] Even when the required sample size has been secured during the recruitment phase, participants may drop out or not respond to questionnaires during the study period. Previously reported background factors and causes of non-response to questionnaires or attrition from interviews are young age, smoking, number of children, psychological stress and lower socioeconomic status. ...
Objectives
We examined whether providing educational events for participants in a birth cohort study would increase the response rates of study questionnaires.
Design
Birth cohort study.
Setting
Questionnaires were distributed and returned by post twice in 1 year. We developed and implemented two educational sessions; a Baby Food lecture for mothers with children around 8 months old (analysis 1) and a Eurythmic session for mothers with children around 1 year and 8 months old (analysis 2). Mothers with children over the target ages were not invited (not-invited group). The invited participants were divided into three groups: those who did not apply to attend (not-applied group), those who applied but did not attend (applied group), and those who applied and attended (attended group).
Participants
The participants were 5379 mother–child pairs registered with the Toyama Regional Center of the Japan Environment and Children’s Study (JECS).
Outcome measure
The outcome measure was return of the JECS questionnaire for 1 year old sent out after the Baby Food lecture and the JECS questionnaire for 2 years old sent out after the Eurythmic session. The questionnaires were returned to us by post.
Results
The response rate for the attended group of the Baby Food lecture was 99.7%, and the odds ratio (OR) was significantly higher for this group than for the not-invited group (crude OR 24.54; 95% confidence interval (CI) 3.42 to 176.13; analysis 1). After the exclusion of participants who had previously attended the Baby Food lecture, the response rate for the attended group of the Eurythmic session was 97.8%, and the OR was significantly higher for this group than for the not-invited group (adjusted OR 5.66; 95% CI 1.93 to 16.54; analysis 2).
Conclusion
Providing educational events that are appropriate to the age and needs of the participants may increase questionnaire response rates in birth cohort studies.
Trial registration number
UMIN 000030786.
... As such, there was only one mailing and if the patient did not return to the health care facility there was no other opportunity to complete the surveys, therefore we do not know the reason for the non-responses, We recognize that the response rate or these surveys is low (18.2%) but it should be recognized that the response rates of surveys have been steadily declining in recent years. [23][24][25][26][27][28] and the response rate of 18.2% is actually on the upper end of standard survey response rate (14.2%) for electronic surveys. 29 In addition to the limitations discussed above regarding the characteristics of respondents, there is likely some response bias in that those with more severe symptoms were more likely to respond. ...
Objective:
Persistent post-COVID symptoms are estimated to occur in up to 10% of patients who have had COVID-19. These lingering symptoms may persist for weeks to months after resolution of the acute illness. This study aimed to add insight into our understanding of certain post-acute conditions and clinical findings. The primary purpose was to determine the persistent post COVID impairments prevalence and characteristics by collecting post COVID illness data utilizing Patient-Reported Outcomes Measurement Information System (PROMIS®). The resulting measures were used to assess surveyed patients physical, mental, and social health status.
Methods:
A cross-sectional study and 6-months Mayo Clinic COVID recovered registry data were used to evaluate continuing symptoms severity among the 817 positive tested patients surveyed between March and September 2020. The resulting PROMIS® data set was used to analyze patients post 30 days health status. The e-mailed questionnaires focused on fatigue, sleep, ability to participate in social roles, physical function, and pain.
Results:
The large sample size (n = 817) represented post hospitalized and other managed outpatients. Persistent post COVID impairments prevalence and characteristics were determined to be demographically young (44 years), white (87%), and female (61%). Dysfunction as measured by the PROMIS® scales in patients recovered from acute COVID-19 was reported as significant in the following domains: ability to participate in social roles (43.2%), pain (17.8%), and fatigue (16.2%).
Conclusion:
Patient response on the PROMIS® scales was similar to that seen in multiple other studies which used patient reported symptoms. As a result of this experience, we recommend utilizing standardized scales such as the PROMIS® to obtain comparable data across the patients' clinical course and define the disease trajectory. This would further allow for effective comparison of data across studies to better define the disease process, risk factors, and assess the impact of future treatments.
... Conversely, in subsequent rounds, seropositivity was directly tested for using a type-specific immunodot assay [18]. It remains unknown whether differences in sampling weights, or in response rate and survey adjustments, may also contributed to this discrepancy [17,18,72]. This discrepancy argues for reexamination of stored sera of that round, or other stored sera from that era, and testing it using current gold standard methods to clarify actual seroprevalence. ...
Background
We analytically characterized the past, present, and future levels and trends of the national herpes simplex virus type 2 (HSV-2) epidemic in the United States.
Methods
A population-level mathematical model was constructed to describe HSV-2 transmission dynamics and was fitted to the data series of the National Health and Nutrition Examination Surveys.
Results
Over 1950-2050, antibody prevalence (seroprevalence) increased rapidly from 1960, peaking at 19.9% in 1983 in those aged 15-49, before reversing course to decline to 13.2% by 2020 and 8.5% by 2050. Incidence rate peaked in 1971 at 11.9 per 1,000 person-years, before declining by 59% by 2020 and 70% by 2050. Annual number of new infections peaked at 1,033,000 in 1978, before declining to 667,000 by 2020 and 600,000 by 2050. Women were disproportionately affected, averaging 75% higher seroprevalence, 95% higher incidence rate, and 71% higher annual number of infections. In 2020, 78% of infections were acquired by those 15-34 year-olds.
Conclusions
The epidemic has undergone a major transition over a century, with the greatest impact in those 15-34 year-olds. In addition to 47 million prevalent infections in 2020, high incidence will persist over the next three decades, adding >600,000 new infections every year.
... Although the 14.2% response rate may have resulted in a study sample not being representative of the general population of patients with overweight and obesity receiving health care at study sites, it should be noted that response rates of mailed surveys have been steadily declining in recent years. [51][52][53][54][55][56] In addition, our surveys had a one-time mailing during the US holiday season with a generic cover letter (data collection for this survey occurred from October 27, 2017, through March 1, 2018). It should be noted that the return rate of 14.2% is comparable to that in another study using this database that had a rare disease focus and had a similar approach to data collection. ...
Objective
To assess patients’ weight management needs and experiences across multiple sites within the Learning Health System Network.
Patients and Methods
A total of 19,964 surveys were sent to patients identified with overweight or obesity through medical record query at 5 health care systems throughout 11 states. The survey collected patients’ experiences with and opinions about weight management in clinical care from October 27, 2017, through March 1, 2018.
Results
Among the 2380 responders, being younger, female, nonwhite, and single and having some college education or less were all significantly associated with higher body mass index (BMI). The most frequent weight loss barriers included food cravings (30.7%-49.9%) and having a medical condition limiting physical activity (17.7%-47.1%) (P<.001). Higher BMI was associated with a higher frequency of comorbidities and lower health status (P<.001). Higher BMI was also associated with a higher belief that primary care providers (PCPs) should be involved in weight loss management (P=.01) but lower belief that the PCP had the necessary skills and knowledge to help (P<.001). Responders with a higher BMI were more likely to feel judged (P<.001) and not always respected (P<.001) by their PCP. In addition, those with a higher BMI more frequently reported avoiding health care visits because of weight gain, not wanting to undress or be weighed, and not wanting to discuss their weight with their PCP (P<.001).
Conclusion
Physician involvement in weight management is important to patients whose needs and experiences differ by BMI. These data may inform clinical weight management efforts and create greater alignment with patient expectations.
... This study has a significant set of weaknesses. First, the overall response rate was very low, participation rates for epidemiologic studies have been declining over the past 30 years (Bradburn, 1992;Groves, 2004), and even more so in recent years (Curtin et al., 2005;Nohr et al., 2006) this not only applies to academic studies but profit making organisations (Tortora, 2004) and government departments have also reported this (Forthofer, 1983). Although, it is recognised that such populations are challenging to reach with questionnaire-based studies, and an additional reminder was sent in order to improve this where possible. ...
Objective
Work aggravated asthma (WAA), asthma made worse by but not caused by workplace exposures, can have a negative impact on personal, social, financial and societal costs. There is limited data on prevalence levels of WAA in Great Britain (GB). The objective of this study was to estimate the prevalence of WAA in GB, and to assess its potential causes.
Materials and methods
A cross-sectional postal questionnaire study was carried out. A total of 1620 questionnaires were sent to three populations of adults with asthma. The questionnaire recorded; demographic details, current job, self-reported health status, presence of asthma and respiratory symptoms, duration and severity of symptoms and medication requirements. Questions relating to work environment and employers’ actions were included, and each participant completed an assessment of health-related quality of life using the EuroQol Research Foundation EQ-5D.
Results
There were 207 completed questionnaires; response rates were 6% primary care, 45% secondary care and 71% Asthma UK. This represented a 13% overall response rate. Self-reported prevalence of WAA was 33% (95% CI 24.4–41.6%). In all, 19% of workers had changed their job because of breathing problems. Workers with WAA reported higher levels of work-related stress. Quality of life using the EQ-5D utility index was lower in those with WAA.
Conclusion
WAA is a common problem in asthmatics in GB. This result is in keeping with international prevalence rates. Further research could assist the understanding of the most significant aggravants to asthma at work and help define appropriate interventions by workplaces.
... Participation in studies has also been associated with behavioral variables and with general state of health. Non-participants report greater consumption of alcohol, smoking and poor general state of health 12,15,2019,21,22,23,26,27,28,29,30,31,32,33,34 . This information, however, are not available in most publications, limiting the scope of our study. ...
The proportion of non-participation in cohort studies, if associated with both the exposure and the probability of occurrence of the event, can introduce bias in the estimates of interest. The aim of this study is to evaluate the impact of participation and its characteristics in longitudinal studies. A systematic review (MEDLINE, Scopus and Web of Science) for articles describing the proportion of participation in the baseline of cohort studies was performed. Among the 2,964 initially identified, 50 were selected. The average proportion of participation was 64.7%. Using a meta-regression model with mixed effects, only age, year of baseline contact and study region (borderline) were associated with participation. Considering the decrease in participation in recent years, and the cost of cohort studies, it is essential to gather information to assess the potential for non-participation, before committing resources. Finally, journals should require the presentation of this information in the papers.
... Field substitution to address differential non-response has little effect on the results [64] but post-survey adjustments (e.g. non-response; weighting) removes these differences, [61,64,65] with a suggestion to reduce fieldwork costs (or increase sample size) by reducing efforts to contact or convert non-responders and weighting data instead [61,66]. ...
Background
Health examination surveys (HESs), carried out in Europe since the 1950’s, provide valuable information about the general population’s health for health monitoring, policy making, and research. Survey participation rates, important for representativeness, have been falling. International comparisons are hampered by differing exclusion criteria and definitions for non-response.
Method
Information was collected about seven national HESs in Europe conducted in 2007–2012. These surveys can be classified into household and individual-based surveys, depending on the sampling frames used. Participation rates of randomly selected adult samples were calculated for four survey modules using standardised definitions and compared by sex, age-group, geographical areas within countries, and over time, where possible.
Results
All surveys covered residents not just citizens; three countries excluded those in institutions. In two surveys, physical examinations and blood sample collection were conducted at the participants’ home; the others occurred at examination clinics. Recruitment processes varied considerably between surveys. Monetary incentives were used in four surveys. Initial participation rates aged 35–64 were 45 % in the Netherlands (phase II), 54 % in Germany (new and previous participants combined), 55 % in Italy, and 65 % in Finland. In Ireland, England and Scotland, household participation rates were 66 %, 66 % and 63 % respectively. Participation rates were generally higher in women and increased with age. Almost all participants attending an examination centre agreed to all modules but surveys conducted in the participants’ home had falling responses to each stage. Participation rates in most primate cities were substantially lower than the national average. Age-standardized response rates to blood pressure measurement among those aged 35–64 in Finland, Germany and England fell by 0.7-1.5 percentage points p.a. between 1998–2002 and 2010–2012. Longer trends in some countries show a more marked fall.
Conclusions
The coverage of the general population in these seven national HESs was good, based on the sampling frames used and the sample sizes. Pre-notification and reminders were used effectively in those with highest participation rates. Participation rates varied by age, sex, geographical area, and survey design. They have fallen in most countries; the Netherlands data shows that they can be maintained at higher levels but at much higher cost.
... 35 Finally, all surveys, including NHANES, suffer from a nonresponse bias, but nonresponse and poststratification adjustments performed by the NCHS adjust for, and largely remove, these as sources of bias. 36 In summary, the recent NHANES with oversampling of non-Hispanic Asians indicates that during 2011-2012, there were approximately 850,000 Americans with chronic HBV infection (400,000 non-Hispanic Asians). There has been decreasing prevalence of persons with serological evidence of past HBV infection (anti-HBc) and increasing immune protection (anti-HBs) in young persons vaccinated in infancy, given that they now age. ...
The number of persons with chronic hepatitis B virus (HBV) infection in the United States is affected by diminishing numbers of young persons who are susceptible because of universal infant vaccination since 1991, offset by numbers of HBV-infected persons migrating to the United States from endemic countries.
The prevalence of HBV infection was determined by serologic testing and analysis among non-institutionalized persons aged 6 years and older for: antibody to hepatitis B core antigen (anti-HBc), indicative of prior HBV infection; hepatitis B surface antigen (HBsAg), indicative of chronic (current) infection; and antibody to hepatitis B surface antigen(anti-HBs), indicative of immunity from vaccination. These prevalence estimates were analyzed in three periods of the National Health and Nutrition Examination Survey (NHANES): 1988-1994 (21,260 persons); 1999-2008 (29,828); and 2007-2012 (22,358). In 2011-2012, for the first time, non-Hispanic Asians were oversampled sampled in NHANES.
For the most recent period (2007-2012), 3.9% had anti-HBc, indicating about 10.8 (95% CI 9.4-12.2) million non-institutionalized US residents having ever been infected with HBV. The overall prevalence of chronic HBV infection has remained constant since 1999: 0.3% (95% confidence intervals, 0.2% - 0.4%), and since 1999, prevalence of chronic HBV infection among non-Hispanic blacks has been 2-3 fold greater than the general population. An estimated 3.1% (1.8% - 5.2%) of non-Hispanic Asians were chronically infected with HBV during 2011-2012; which reflects a 10-fold greater prevalence than the general population. Adjusted prevalence of vaccine induced immunity increased 16% since 1999, and the number of persons (mainly young) with serologic evidence of vaccine-protection from HBV infection rose from 57.8 (95% CI 55.4-60.1) million to 68.5 (95% CI 65.4-71.2) million.
Despite increasing immune protection in young persons vaccinated in infancy, an analysis of chronic hepatitis B prevalence in racial and ethnic populations indicates that during 2011-2012 there were 847,000 HBV infections (which included ∼400,000 non-Hispanic Asians) in the non-institutionalized US population. This article is protected by copyright. All rights reserved.
© 2015 by the American Association for the Study of Liver Diseases.
... The NHANES III data, which is not used directly in this analysis, confirms that this swift downward movement continued in the 1980s. 38 While there was a 27% non-response rate at the examination phase, Forthofer (1983) uses a comparison to the 1976 National Health Interview Survey to show that "the nonresponse and poststratiftcation adjustments performed by the National Center for Health Statistics" have effectively eliminated non-response bias. 39 See the above note re methods of measuring lead in the human body. ...
It is well known that exposure to lead has numerous adverse effects on behavior and development. Using data on two cohorts of children from the NLSY, this paper investigates the effect of early childhood lead exposure on behavior problems from childhood through early adulthood. I find large negative consequences of early childhood lead exposure, in the form of an unfolding series of adverse behavioral outcomes: behavior problems as a child, pregnancy and aggression as a teen, and criminal behavior as a young adult. At the levels of lead that were the norm in United States until the late 1980s, estimated elasticities of these behaviors with respect to lead range between 0.2 and 1.0.
... The NHANES II survey used a highly stratified multistage probability design to obtain a representative sample of the noninstitutionalized population of the United States, aged 6 months to 74 years (3). Of the 17,437 black or white adults (19-74 years of age) in the sample, 11,938 (68 per cent) were examined in the NHANES II survey; no significant nonresponse bias resulted (11). The present study used dietary intake data from 11,658 black or white adults, 98 per cent of those examined, representing 132 million individuals in the US noninstitutionalized population. ...
... Nonresponse has been to derive estimates of the distribution of age at infection and the contact rate, or force of infection. The force of infection is defined examined in NHANES II [20] and NHANES III [21] and has been further examined for its possible effects on estimates of the as the rate at which susceptible persons acquire HBV infection and reflects both the type and frequency of exposure, as well as prevalence of human immunodeficiency virus (HIV) infection for some age and racial groups [22]. For HIV, it was assumed that infection persistence. ...
Precise estimates of the incidence of hepatitis B virus (HBV) infection are required to assess the impact of immunization
and other prevention strategies in the United States. Race- and age-specific prevalence data obtained from the second and
third National Health and Nutrition Examination Surveys (NHANES II, 1976–1980, and NHANES III, 1988–1994) were used to estimate
the annual incidence of HBV infection by catalytic modeling. During the period covered by NHANES II, an estimated 323,462
persons were infected annually, and 334,863 were infected annually during the period covered by NHANES III. No statistically
significant declines in prevalence of HBV infection occurred between the two surveys, a period during which hepatitis B vaccination
targeted only limited numbers of high-risk adults.
... However, other studies find higher healthcare use for respondents or better health status for non-respondents2930313233. So far, few studies have investigated selection mechanisms in second-stage non-response in HIS designs [22,34] . At the second stage, HIS participants are asked to participate in yet another survey. ...
Background:
Unit non-response occurs in sample surveys when a target subject does not respond to a survey. Potential implications are decreased power, increased standard error, and non-response bias. The objective of this study was to assess the factors associated with participation in a written survey (MSHS) of subjects who had previously participated in the Swiss Health Survey (SHS) and to evaluate to what extent non-participation could impact the estimation of various MSHS health outcomes.
Methods:
Multivariate logistic regression was used to assess the factors associated with MSHS participation (n=14,393) by eligible SHS participants (n=17,931). Crude participation rates and the adjusted odds ratios of participation (OR) were reported. In order to report potential bias in MSHS outcomes, the average age-standardized and sex-specific outcome values in non-participants were predicted based on several different linear regression models which had been previously fitted on MSHS participants.
Results:
Adjusting for all other variables, women (OR=1.63) as compared with men, subjects with a secondary (OR=1.48) or tertiary education (OR=1.76) as compared with those with primary education, white-collar workers (high level non-manual workers OR=1.29, medium and low level non-manual workers OR=1.26 and OR=1.25 respectively) as compared with unskilled manual workers, Swiss nationals (OR=1.60) as compared to non-Swiss, and subjects with very good or good self-rated health (OR=1.35) were more likely to participate in the MSHS. People who work full-time were less likely to participate than those without paid work (OR=0.76). There were no statistically significant differences in the likelihood of participation between rural and urban areas, different geographic regions of Switzerland and household income quartiles.
Except for myocardial infarction, all age-standardized and sex-specific average outcomes (influenza vaccination, arthrosis, osteoporosis, high blood pressure, depression, mastery, and sense of coherence) were significantly different between MSHS non-participants and participants.
Conclusions:
Subjects who participated in the MSHS had a higher socio-economic status, reported a better subjective health, and were more likely to be Swiss nationals. Small to moderate bias was found for most age-adjusted and sex-specific average outcomes. Consequently, these MSHS outcomes should be used and interpreted with care.
... Approximately 50% of clinical trials, observational studies and laboratory-based experimental studies have difficulties with recruitment (2). Researchers must make timely and successful contact with potential research participants as a first step in achieving the goal of timely and complete recruitment of a representative study population (3)(4)(5). ...
To study the effect of different mail- and phone-based strategies, along with patient- and research-related factors, on the time to contact with research participants.
A prospective evaluation of a 12-week standardized protocol (embedded with two randomized trials of mail- and phone-based strategies) for contacting existing research participants for recruitment into a related study.
Of 146 participants, 87 were eligible for contact via the standardized protocol, and 63 (72%) of these were successfully contacted within 12 weeks after multiple mail- and phone-based efforts. Using Cox proportional hazards regression analysis, the different mail and phone strategies showed no significant difference in the time to contact with participants. Of 34 patient- and research-related factors evaluated, only two were independently associated with time to contact among all 146 participants: (1) participants having their last visit conducted outside of the research clinic because of patient illness/condition had a longer time to contact and (2) those with a self-reported chronic fatigue history had a shorter time to contact.
Few patient characteristics and research-related factors accurately predict time to contact. Repeated attempts using different strategies are important for successful and timely contact with study participants.
... In general, nonrespondents tend to be younger than respondents and they are more likely to be single, have lower education and have a worse health profile [129,130]. People with physical problems are more likely to participate in health surveys [131]. When comparing the early respondents, intermediate and late respondents, initial and passive refusers, and those who are hard to contact, one finds some distinct differences between these groups ( Table 9). ...
... Investigations of factors affecting participation in two-stage studies, the designs of which resemble that of the HEIRS study, have shown greater participation among those with specific health concerns (Cobb et al., 1957). For example, those who participated in the examination phase of National Health and Nutrition Examination Survey II were more likely than nonparticipants to have a health problem they wished to discuss with a physician (Forthofer, 1983). In the present study, the ORs for controls who reported that it was ''mostly true'' that their health was going to get worse and those who felt this was ''definitely true'' were not statistically significant. ...
Little is known about the factors affecting participation in clinical assessments after HEmochromatosis and IRon Overload Screening.
Initial screening of 101,168 primary care patients in the HEmochromatosis and IRon Overload Screening study was performed using serum iron measures and hemochromatosis gene (HFE) genotyping. Using iron phenotypes and HFE genotypes, we identified 2256 cases and 1232 controls eligible to participate in a clinical examination. To assess the potential for nonresponse bias, we compared the sociodemographic, health status, and attitudinal characteristics of participants and nonparticipants using adjusted odds ratios (ORs) and 95% confidence interval (CI).
Overall participation was 74% in cases and 52% in controls; in both groups, participation was highest at a health maintenance organization and lowest among those under 45 years of age (cases: OR = 0.68; 95% CI 0.53, 0.87; controls: OR = 0.59; 95% CI 0.44, 0.78). In controls only, participation was also lower among those over 65 years of age than the reference group aged 46-64 (OR = 0.64; 95% CI 0.47, 0.88). Among cases, participation was higher in HFE C282Y homozygotes (OR = 3.98; 95% CI 2.60, 6.09), H63D homozygotes (OR = 2.79; 95% CI 1.23, 6.32), and C282Y/H63D compound heterozygotes (OR = 1.82; 95% CI 1.03, 3.22) than in other genotypes, and lower among non-Caucasians and those who preferred a non-English language than in Caucasians and those who preferred English (p < 0.0001).
Subjects with greatest risk to have iron overload (C282Y homozygotes; cases > or =45 years; Caucasians) were more likely to participate in a postscreening clinical examination than other subjects. We detected no evidence of strong selection bias.
... En lo que se refiere a la proporción de sujetos que participaron plenamente hasta completar el EMPDB y CUADRO 1. Tamaño de las muestras usadas para estimar la prevalencia de diabetes mellitus por cada método evaluado, sexo y grupo de edad en nueve capitales de estados del Brasil, 1986 a 1988 Grupo los que se perdieron o lo abandonaron, el estudio brasileño se compara favorablemente con estudios similares llevados a cabo en otros países (22)(23)(24)(25)(26). Dados los objetivos inmediatos y la magnitud del EMPDB, no se investigó en detalle a los sujetos que no completaron su participación, los cuales se incluyen en la figura 1 como pérdidas. ...
Con objeto de aportar información necesaria en la búsqueda de métodos más prácticos y fiables para estudios de base poblacional sobre la diabetes mellitus, en este trabajo se comparan cinco formas de estimar las tasas de prevalencia. Se analizaron datos secundarios de un estudio transversal en una muestra por conglomerados de la población adulta residente en nueve capitales de estados del Brasil, realizado de 1986 a 1988. Los 21 846 participantes originales se clasificaron en diabéticos o no diabéticos de acuerdo con cinco métodos distintos: cuestionario domiciliario de toda la población de la muestra (M1), cuestionario individual de la población seleccionada (M2), medición de glucemia capilar en ayunas > o = 120 mg/dL (M3), cuestionario individual y glucemia capilar en ayunas > o = 120 mg/dL (M4) y cuestionario individual y glucemia capilar en ayunas > o = 200 mg/dL y glucemia capilar 2 horas después de sobrecarga oral de glucosa > o = 200 mg/dL (M5). Se determinó la concordancia entre los cinco métodos por comparación de las tasas obtenidas y empleo del coeficiente kappa. Las tasas de prevalencia de diabetes estandarizadas por edad variaron según el método analizado; con M1 se subestimaron los valores detectados por M2; con M3 se calcularon valores más altos que con M2 excepto en el grupo de edad de 60 a 69 años, y con M5 las tasas fueron más altas que con M4 excepto en el grupo de edad de 30 a 39 años. Según las tasas estandarizadas por edad, M1 detectó 84% de los valores estimados por M2; M2 detectó 91% de los de M3; M3 detectó 70% de los de M4; y M4 detectó 86% de los de M5. Las estimaciones de diabetes previamente diagnosticada fueron 64% y 55% del total estimado por M4 y M5, respectivamente. Los valores kappa fueron iguales a 0,70 o mayores en M1 contra M2, M1 contra M4, M2 contra M4 y M3 contra M4. Dados los resultados de este estudio, se concluye que los cuestionarios usados en M1 y M2 son métodos apropiados para detectar los casos de diabetes mellitus previamente diagnosticados y se recomienda su uso para evaluaciones o planeamiento de servicios de salud. La medición de glucemia en ayunas (M3) como método exclusivo no reportó ventajas sobre el cuestionario individual (M2). Entre los métodos combinados o múltiples, la glucemia en ayunas junto con el cuestionario individual (M4) fue eficiente en relación con M5, que incorpora la glucemia a las 2 horas después de la ingestión de una sobrecarga oral de glucosa.
... Furthermore, we found signifi cant differences between respondents and nonrespondents in terms of age, with smokers aged 25 -54 years more likely to drop out. This may have impacted upon the results, although past research reporting similar response bias in terms of age suggests that this does not affect the conclusions drawn from these studies ( Benfante, Reed, MacLean, & Kagan, 1989 ;Forthofer, 1983 ;Heilbrun, Nomura, & Stemmermann, 1991 ). ...
The longitudinal ITC Scotland/U.K. survey was used to investigate adult smokers' support for smoke-free legislation and whether this support was associated with higher quit intentions at follow-up, either directly or indirectly, via the mediation of perceived social unacceptability of smoking.
Structural equation modeling was employed to compare differences between the two samples (507 adult smokers from Scotland and 507 from the rest of the United Kingdom) across two waves (February/March 2006 and March 2007). During these two waves, a smoking ban was introduced in Scotland but not the rest of the United Kingdom.
For smokers in both samples, support for smoke-free legislation at baseline significantly heightened perceived unacceptability of smoking, although perceptions of unacceptability were somewhat stronger in Scotland than the rest of the United Kingdom postban. Unlike the rest of the United Kingdom, support for a ban at baseline among smokers in Scotland was associated with higher quit intentions at follow-up. For both samples, quit intentions were significantly associated with heightened perceived unacceptability at follow-up. The overall variance explained in quit intentions was greater in Scotland than in the rest of the United Kingdom but not significantly so.
Support for smoke-free legislation at baseline significantly increased support at follow-up for both samples. However, this did not independently increase quit intentions among smokers from both Scotland and the rest of the United Kingdom. The findings suggest that normative influences are one of the mechanisms through which comprehensive smoke-free legislation influences quit intentions.
... Trent and Ames,'4 summarising earlier studies on nonresponse, found no consistent relationship between participation and objective measures of health status whereas several studies have found an association between self reported symptoms and participation. [15][16][17] We found an increased number ofadmissions to hospital due to respiratory disease in general and chronic obstructive lung disease among nonresponders when comparing with responders. Similarly, Cobb et a14 found a threefold increase in the proportion of men who had had three or more hospital admissions in the preceding five years. ...
The aim was to examine whether baseline characteristics from a cross sectional survey provided sufficient information regarding non-response bias in a follow up study when compared with information on hospital admissions in the intervening years.
This was an 11 year follow up study of a cohort selected in 1974 with register information on hospital admissions during follow up.
The study was based on a sample of cement workers from a particular Portland cement factory with suitable controls from other occupations.
A total of 1404 men participated in the first survey in 1974, including a questionnaire and lung function tests. In 1985 1070 men were alive and of these, 928 men (87%) responded to a postal questionnaire.
Non-responders in 1985 did not differ markedly from responders when smoking habits, respiratory symptoms, and lung function were examined in 1974. During follow up, non-responders had twice as high rates of hospital admission due to respiratory diseases as responders. These differences remained present after adjusting for minor differences in age and smoking habits.
Equal distributions of baseline characteristics among responders and non-responders in a follow up study do not preclude non-response bias.
... In addition, it is important to know whether specific items are more or less likely to be answered by those who do participate (item nonresponse bias). Investigation of total nonresponse to surveys has received a great deal of attention in the literature (e.g., Carlsson & Svardsudd, 1985;Criqui, Barrett-Connor, & Austin, 1978;Forthofer, 1983;Heilbrun, Nomura, & Stemmerman, 1982;Williams & McDonald, 1986). Less attention has been directed toward the quality of data in surveys returned by respondents. ...
We examined item nonresponse in questionnaires that assessed the physical functioning, emotional status, and satisfaction with care of surgical patients recently discharged from the hospital following coronary artery bypass graft surgery (CABG; N = 267), total hip replacement (THR; N = 283), and transurethral prostatectomy (TURP; N = 292). For all conditions, the total number of missing responses did not vary with age. More functional and healthier CABG and THR patients generated fewer missing responses than less healthy patients, whereas less educated TURP patients responded to items less frequently than more educated patients. The correlates of specific item nonresponse varied across samples. Most often, perceived health status, assistance with completion of the questionnaire, and patient-reported confusion all related to whether or not specific items were missing. The influence of these variables, however, varied by surgical condition. These results indicate that a proportion of elderly and sick respondents may not respond to at least some items, but it is possible to achieve a high level of data completeness if multiple item scales are used and questions are carefully designed to be salient to the population studied.
Introduction: Cigarette smoking induces many chronic illnesses, but in developed countries it is a preventable risk factor. However, by increasing the protective protection mechanism, it may be possible to alleviate the smoke-induced damage. As smoking risk is minimised by vitamin C intake, it is recommended that smokers should take more vitamin C. This inverse correlation between both vitamin C intake and serum levels and smoking was independent of age, sex, body weight, ethnicity, and consumption of alcoholic beverages. The negative association between cigarette smoking and serum vitamin C levels continued, following further adjustment for dietary vitamin C intake. The risk of severe hypovitaminosis C, especially when not accompanied by vitamin supplementation, has been increased in smokers. These data indicate that the inverse relationship between smoking and serum vitamin C levels exists independently of dietary intake, while smoking adversely affects preferences for vitamin C rich foods. Methods: A survey method was performed, with 50 smokers (S) receiving either 500 mg of vitamin C or placebo (P) daily for 4 weeks, and 50 non-smokers receiving vitamin C without supplementation. All finished the hearing. Both groups were equal and C: 14.2 + /- 1.8 pack-years was the amount of cigarettes smoked. Concentrations of plasma vitamin C increased significantly (p < 0.005) only in the vitamin C supplement community. Results: At SMHRC Hospital Nagpur, we examined the relationship between smoking and vitamin C status, dietary and serum vitamin C levels of 100 participants. Smokers of 20 cigarettes a day had the lowest dietary intake of vitamin C and serum levels, whereas smokers of 1-19 cigarettes a day had lower intake of vitamin C and serum levels (compared to respondents who had never smoked. This inverse correlation between vitamin C and smoking intake and serum levels was independent of age, sex, body weight, race, and consumption of alcoholic beverages. The negative association between cigarette smoking and serum vitamin C levels continued, following further adjustment for dietary vitamin C intake. In smokers, the risk of severe hypo-vitaminosis C, particularly when not accompanied by vitamin supplementation, has increased. Conclusion: These data indicate that the inverse relationship between smoking and serum vitamin C levels exists independently of dietary intake, while smoking adversely affects preferences for vitamin C rich foods. A balanced diet for smokers will obtain a hearty recommendation at this time, but guidelines should remain cautious about high-dose nutrition supplements. Keywords: Chain Smoker, Vitamin C, hypo-vitaminosis C and cigarette.
Background
A high participation rate is warranted in order to ensure validity in surveys of the general population. However, participation rates in such studies have declined during the last decades.
Objective
To evaluate the reasons for and potential effects of non-response in a large population-based survey about asthma and respiratory symptoms in Northern Sweden.
Methods
Within the Obstructive Lung Disease In Norrbotten (OLIN) studies, a random sample of 12,000 adults aged 20–79 was invited to a postal questionnaire survey about asthma, allergic rhino-conjunctivitis and respiratory symptoms in 2016. Three reminders were sent. A random sample of 500 non-responders was invited to a telephone interview.
Results
The participation rate in the initial mailing was 41.4%, and 9.2%, 5.0%, and 2.6% in the subsequent three reminders and totally 58.3% (n = 6854) responded. Of 500 non-responders selected for telephone interviews, 320 were possible to reach and 272 participated. Male sex, younger age, and current smoking were associated with both late and non-response. The prevalence of asthma and most respiratory symptoms did not differ significantly between responders and non-responders while allergic rhino-conjunctivitis and smoking was more common among non-responders. Reminders increased the participation rate but did not alter risk ratios for smoking and occupational exposures. Reasons for non-response were mainly lack of time and having forgotten to answer.
Conclusions
With a response rate of 58.3%, neither the prevalence estimates of asthma, respiratory symptoms nor the associations to risk factors were affected, while allergic rhino-conjunctivitis and smoking was underestimated in this Swedish population.
By the middle of this century, racial/ethnic minority populations will collectively constitute 50% of the US population. This temporal shift in the racial/ethnic composition of the US population demands a close look at the race/ethnicity-specific burden of morbidity and premature mortality among survivors of childhood cancer. To optimize targeted long-term follow-up care, it is essential to understand whether the burden of morbidity borne by survivors of childhood cancer differs by race/ethnicity. This is challenging because the number of minority participants is often limited in current childhood cancer survivorship research, resulting in a paucity of race/ethnicity-specific recommendations and/or interventions. Although the overall childhood cancer incidence increased between 1973 and 2003, the mortality rate declined; however, these changes did not differ appreciably by race/ethnicity. The authors speculated that any racial/ethnic differences in outcome are likely to be multifactorial, and drew on data from the Childhood Cancer Survivor Study to illustrate the various contributors (socioeconomic characteristics, health behaviors, and comorbidities) that could explain any observed differences in key treatment-related complications. Finally, the authors outlined challenges in conducting race/ethnicity-specific childhood cancer survivorship research, demonstrating that there are limited absolute numbers of children who are diagnosed and survive cancer in any one racial/ethnic minority population, thereby precluding a rigorous evaluation of adverse events among specific primary cancer diagnoses and treatment exposure groups. Cancer 2016. © 2016 American Cancer Society.
Public health monitoring depends on valid health and disability estimates in the population 65+ years. This is hampered by high non-participation rates in this age group. There is limited insight into size and direction of potential baseline selection bias.
We analyzed baseline non-participation in a register-based random sample of 1481 inner-city residents 65+ years, invited to a health examination survey according to demographics available for the entire sample, self-report information as available and reasons for non-participation. One year after recruitment, non-responders were revisited to assess their reasons.
Five groups defined by participation status were differentiated: participants (N = 299), persons who had died or moved (N = 173), those who declined participation, but answered a short questionnaire (N = 384), those who declined participation and the short questionnaire (N = 324), and non-responders (N = 301). The results confirm substantial baseline selection bias with significant underrepresentation of persons 85+ years, persons in residential care or from disadvantaged neighborhoods, with lower education, foreign citizenship, or lower health-related quality of life. Finally, reasons for non-participation could be identified for 78 % of all non-participants, including 183 non-responders.
A diversity in health problems and barriers to participation exists among non-participants. Innovative study designs are needed for public health monitoring in aging populations.
This study used data from the Hispanic Health and Nutrition Examination Survey to examine associations between bilateral visual acuity and depression among Cuban American, Mexican American, and Puerto Rican adults. Among Mexican Americans, the odds of current depression were significantly higher for those with moderate and greater impairment distance acuity (20/80 or worse). Among Cuban Americans, the odds of lifetime history of major depressive disorder were significantly higher for those with a distance visual acuity worse than 20/50. There were no significant associations between either past or current depression and impaired visual acuity in Puerto Ricans. These findings provide only limited support for the hypothesis that odds of past and current depression are greater in Hispanics with impaired visual acuity than in Hispanics who are fully sighted.
Unlabelled:
A hepatitis C virus (HCV)-infected person will ideally have access to quality health care and move through the HCV continuum of care (CoC) from HCV antibody (Ab) screening, HCV-RNA confirmation, engagement and retention in medical care, and treatment. Unfortunately, studies show that many patients do not progress through this continuum. Because these studies may not be generalizable, we assessed the HCV CoC in Philadelphia from January 2010 to December 2013 at the population level. The expected HCV seroprevalence in Philadelphia during 2010-2013 was calculated by applying National Health and Nutrition Examination Survey prevalences to age-specific census data approximations and published estimates of homeless and incarcerated populations. HCV laboratory results reported to the Philadelphia Department of Public Health and enhanced surveillance data were used to determine where individuals fell on the continuum. HCV CoC was defined as follows: stage 1: HCV Ab screening; stage 2: HCV Ab and RNA testing; stage 3: RNA confirmation and continuing care; and stage 4: RNA confirmation, care, and HCV treatment. Of approximately 1,584,848 Philadelphia residents, 47,207 (2.9%) were estimated to have HCV. Positive HCV results were received for 13,596 individuals, of whom 6,383 (47%) had a positive HCV-RNA test. Of these, 1,745 (27%) were in care and 956 (15%) had or were currently receiving treatment.
Conclusion:
This continuum provides a real-life snapshot of how this disease is being managed in a major U.S. urban center. Many patients are lost at each stage, highlighting the need to raise awareness among health care professionals and at-risk populations about appropriate hepatitis testing, referral, support, and care.
Non-response bias can distort the results of health surveys. The occurrence of selective non-response can be assessed when data are available for both respondents and non-respondents. The objective of this study was to compare the medical consumption of respondents and non-respondents to a mailed health survey. A mailed health survey was conducted among approximately 13,500 adults and among parents of approximately 1,500 children aged 5-15 years. The net response rate was 70.4%. A panel data set that could be matched with the health survey data was available for all eligible persons. This data set comprises administrative information on hospitalizations, annual health care expenditures and demographic variables. The results of this study show that response was associated with age, sex, degree of urbanization and type of insurance. After correcting for differences in demographic variables, respondents and non-respondents differ in the utilization of several types of care. Relatively more users than non-users responded. Response was not associated with the utilization of care related to severe conditions such as in-patient hospital care. The conclusion from this study is that when a mailed health survey is used to measure medical consumption, the non response bias will result in a small overestimation of utilization.
We have assessed predictors for response in a Norwegian community cohort study, with an 11-year follow-up. We also examined to what extent the association of gender, age, and smoking to the incidence of respiratory symptoms and asthma differed if the analyses were based on the 65% (n = 2,079) initial responders, or were based on the 89% (n = 2,819) who responded after three reminders. The associations between the six symptoms/asthma and the gender, age, and smoking groups amounted to 42 odds ratios. The adjusted odds ratio for responding at follow-up was 1.39 (95% CI: 1.01, 1.90) for those being middle aged at baseline compared to younger subjects. The adjusted odds ratios for responding at follow-up for those being students, unemployed, or retired at baseline were 0.50 (95% CI: 0.35, 0.73), 0.29 (95% CI: 0.16, 0.55), 0.21 (95% CI: 0.13, 0.36), respectively, compared to being employed. Of the 42 odds ratios mentioned above, 25 differed less than 10% when comparing the initial and all respondents. Twelve differed 10–20% and five differed 20–45%. The study indicates that to ensure a high participation rate in a follow-up study one should pay special attention to those being late responders, unemployed, retired, or students at baseline. No overt differences were observed in the gender, age, and, smoking associations to the respiratory disorders when the analyses were based on the initial compared to all respondents.
Characterization of nonrespondents, with the aim of detecting nonresponse bias, is a crucial component of prospective studies. This study was undertaken to investigate the demographic and health characteristics of nonrespondents to a population-based cohort study of cardiovascular disease, to determine whether early-stage nonrespondents differ from late-stage nonrespondents, and to estimate the bias in prevalence estimates for the source population. Sixty-seven percent of eligible subjects completed all phases of the cohort recruitment. Compared to respondents, nonrespondents were less likely to be married, less likely to be employed, and less likely to be well educated. Nonrespondents tended to describe their general health in less favorable terms and were more likely to be smokers. Their reported disease profile, however, was not dissimilar to that of respondents. For several demographic and health characteristics, including marital status, education, and smoking, early-stage nonrespondents differed from respondents more than did late-stage nonrespondents. For example, 42% of early nonrespondents were smokers compared to 37% of late nonrespondents and 22% of respondents. Overall, the bias in prevalence estimates related to nonresponse was small (
The prevalence of hepatitis B virus (HBV) infection was dtermined using sera from persons participating in the second National health and Nutrition Examination Survey, conducted from 1976 to 1980. Of 12 to 74,821 had evidence of past or presentinfection with HBV. In the white population, the weighted estimate of hepatitis B infection was 3.2 percent (95 percent confidence interval, 3.1 to 4.2). A steady increase with age was seen; by ages 65 to 74, the confidence interval, 5.2 to 8.5). In the black population, the overall weighted estimate of prevalence was 13.7 percent (95 percent confidence interval, 11.6 to 15.8). In this racial group, there was a dramatic increase with age, with the oldest age groups having a prevalence of 39.6 percent (95 percent confidence interval, 29.1 to 50.0). In both racial groups, there was a low prevalence of infection in young children that began to rise between ages 12 and 18. In a multivariate analysis of factors associated with infection, there was interaction of race with age; therefore, the odds ratio for race is presented for four ages. This ratio ranged from 3.0 (95 percent confidence interval, 1.8 to 4.2) for a 70-year-old. These relative odds estimates were not substantially affected by adjustment for the available information on risk factors for HBV infection. The results of this study in a representative sample of the United States population show that adult black Americans are at high risk for hepatitis B infection. Other independent predictions of HBV positivity include male sex; residing in a city of 250,00 or more people; serving in the armed forces; living below the poverty level; and having a positive treponemal test for syphilis. These dta suggest that the immunization practices for controlling this deases should be re-examined.
Objectives: To determine whether the three mailings routinely used by researchers for epidemiological surveys are useful and appropriate, by comparing social characteristics and selected disease histories to find out if there are differences between individuals responding at different times.
Methods: Social characteristics and selected disease histories of 11,797 British women still under general practitioner observation in the Royal College of General Practitioners' Oral Contraception Study were compared. The women aged 40-78 at December 1992 were sent health survey questionnaires via their general practitioners between November 1994 and July 1995.
Results: Significant differences in the characteristics of first, second and third mailing respondents and non-respondents were found for smoking habits, social class, parity, area of residence, further contact, bronchitis, hysterectomy and mental illness. First mailing respondents were more likely to be from a non-manual social class, have a parity of less than three, live in England, and be happy to be contacted again, but were less likely to have had bronchitis or mental illness and were less likely to have been smokers at the time of recruitment than second mailing respondents. A comparison of second and third mailing respondents on the above factors showed no significant differences between the two groups.
Conclusions: The inclusion of third mailing respondents did not significantly change the social or health characteristic profile of the cohort and suggests that the effort and resources expended in carrying out a third mailing may not be justified.
This study assessed mail survey return rates published in seven general health education journals for the 13-year period, 1990-2002: "American Journal of Health Behavior," "American Journal of Health Education," "American Journal of Health Promotion," "Health Education & Behavior," "Health Education Research," "Journal of American College Health," and the "Journal of School Health." A significant difference in mail survey return rates across the seven journals was found. Also, published mail survey return rates significantly increased from 1990-1995 (M = 61.8%) to 1997-2002 (M = 65.5%). All of the journals had published a noteworthy percentage (10-26%) of their mailed survey research studies with return rates of less than 50%. Finally, there was not a significant association between sample size and return rates of published mail survey studies. Researchers reporting mail survey research results in health education journals should expect to have return rates of 60% or greater. Yet, such return rates may still be considered a significant threat to the external validity of the findings. (Contains 1 table and 1 figure.)
Abstract Obesity is an important social and health issue in contemporary society. Differences in relative weight, overweight, and extreme overweight were examined in rural, middle-sized, and urban areas in a national sample of 11,578 adults in the NHANES II survey. Rural-urban residence and weight were examined in bivariate relationships and in multiple regression analyses controlling for demographic and physical variables. Overall bivariate analyses revealed that some groups in rural areas had higher weights than their more urban counterparts. However, regression analyses showed that many bivariate rural-urban differences disappeared when demographics were controlled, although rural white women and men were still more likely to be overweight relative to their more urban counterparts. These findings suggest that the demographic composition of rural and urban populations explains most, but not all rural-urban variations in weight.
Objectives: Designing research to include sufficient respondents in groups at highest risk for oral health decrements can present unique challenges. Our purpose was to evaluate bias and logistics in this survey of adults at increased risk for oral health decrements. Methods: We used a telephone survey methodology that employed both listed numbers and random digit dialing to identify dentate persons 45 years old or older and to oversample blacks, poor persons, and residents of nonmetropolitan counties. At a second stage, a subsample of the respondents to the initial telephone screening was selected for further study, which consisted of a baseline in-person interview and a clinical examination. We assessed bias due to: (1) limiting the sample to households with telephones, (2) using predominantly listed numbers instead of random digit dialing, and (3) nonresponse at two stages of data collection. Results: While this approach apparently created some biases in the sample, they were small in magnitude. Specifically, limiting the sample to households with telephones biased the sample overall toward more females, larger households, and fewer functionally impaired persons. Using predominantly listed numbers led to a modest bias toward selection of persons more likely to be younger, healthier, female, have had a recent dental visit, and reside in smaller households. Blacks who were selected randomly at a second stage were more likely to participate in baseline data gathering than their white counterparts. Comparisons of the data obtained in this survey with those from recent national surveys suggest that this methodology for sampling high-risk groups did not substantively bias the sample with respect to two important dental parameters, prevalence of edentulousness and dental care use, nor were conclusions about multivariate associations with dental care recency substantively affected. Conclusion: This method of sampling persons at high risk for oral health decrements resulted in only modest bias with respect to the population of interest
The objective of this study was to identify characteristics of non-respondents and late respondents to a mailed health survey. Persons who returned and those who did not return the questionnaire were compared using health insurance data, which indicated their age, sex, and health care expenditures in the previous year. Insurance and questionnaire data were used to compare early and late survey respondents and to compare categories of non-respondents. Questions covered use of health services, health status, and sociodemographic characteristics. Participants were members of health insurance plans in Geneva, Switzerland, 19–45 years old (n = 1822). Respondents (n = 1424) and non-respondents (n = 398) were of similar age and sex. The proportion of persons who had health care expenditures greater than zero Swiss francs (SFr) was higher among respondents (75%) than among non-respondents (69%, p = 0.03). Among non-respondents, expenditures of persons who explicitly refused to participate (2378 SFr) were higher than expenditures of persons who moved out of Geneva (1085 SFr) or who failed to return the questionnaire (1592 SFr, p = 02). Among respondents, being born in a Switzerland, having completed elementary school, having generated health care expenditures, and reporting good physical health were independent predictors of early response. In conclusion, low response rates to mailed health surveys may result in overestimating the utilization of health services. However, non-respondents did not constitute a homogenous group, and the strength and even direction of non-response bias depended on the mechanisms of non-response.
Community pharmacists are being assigned increased responsibility in assuring the appropriateness and effectiveness of drug therapy. This increased responsibility is reflected in recently passed legislation (OBRA '90) in the United States that requires pharmacists to counsel patients about prescriptions received and to engage in prospective drug use review for Medicaid recipients. The potential impact of this legislation is unclear due to a dearth of research evaluating the effects of community pharmacists' activities on medication use. In addition, there is little research on pharmacists' willingness to assume increased responsibility. Research that would demonstrate the effectiveness of community pharmacists in improving therapeutic outcomes is hampered by problems inherent in conducting experimentally designed research in field settings. This paper examines two issues of concern in such studies—namely, the extent to which those who agree to participate in a demonstration project differ from those who decline to participate and the extent to which differential dropout from treatment and control conditions compromise the comparability of the two groups. Specifically, this report examines pharmacist characteristics related to participation in a demonstration project to improve the care of elderly patients. Community pharmacists in Florida who had earlier been asked to participate in a demonstration project (N = 418) were sent mail questionnaires to assess their attitudinal, demographic and employment characteristics. In particular, researchers were interested in the role orientation of pharmacists in regard to patient counseling and physician consultation, satisfaction with current jobs and career choices, employment settings and treatment vs control group assignment as predictors of participation in the research project. Demographic characteristics were also examined as possible predictors of participation.
Historically, an association between tuberculosis and diabetes was recognised clinically, and the recent global rise in diabetes prevalence has reignited interest. We therefore quantified the tuberculosis-diabetes association using US survey data. A case-control analysis was performed using cross-sectional data from the second National Health and Nutrition Examination Survey (1976-1980; civilian non-institutionalised US population aged 20-74). Cases were respondents ever diagnosed with tuberculosis, and controls were respondents who reported never receiving a tuberculosis diagnosis. Exposure to diabetes and intermediate hyperglycaemia was defined using a self-reported measure, an oral glucose tolerance test, or both. We used logistic regression to estimate an adjusted odds ratio, controlling for potential major confounders. In relation to the main exposure measure, the adjusted odds ratio for the association between tuberculosis and diabetes varied between 2.31 (95% confidence interval 1.36-3.93) and 2.36 (95% confidence interval 1.40-3.97), depending on the model. No association was found for intermediate hyperglycaemia, with adjusted odds ratio varying between 1.33 (95% confidence interval 0.49-3.64) and 1.34 (95% confidence interval 0.50-3.62), depending on model. Irrespective of the exposure measure and the confounders controlled for, diabetes was associated with an increased tuberculosis risk. This study may underestimate the true association due to exposure misclassification.
Data from National Health and Nutrition Examination Survey (NHANES) II (1976 to 1980), NHANES III (1988 to 1994), and NHANES 1999 to 2006 were examined to assess trends in total cholesterol (TC), low-density lipoprotein (LDL) cholesterol, high-density lipoprotein cholesterol, triglycerides (TGs), lipid-lowering medication use, and obesity. Age-adjusted decreases in TC (210 to 200 mg/dl) and LDL cholesterol (134 to 119 mg/dl) were observed. Those with high TC showed a decrease of 9% from NHANES II to NHANES 1999 to 2006, whereas those with LDL cholesterol ≥160 mg/dl showed a decrease of 8%. A significant increase in mean high-density lipoprotein cholesterol was observed (50 to 53 mg/dl, p <0.001), most likely due to changes in methods. Those with TG levels ≥150 mg/dl showed a decrease from NHANES II to NHANES III from 30% to 27% but then an increase from NHANES III to NHANES 1999 to 2006 from 27% to 33%. Since NHANES III, mean TG levels have increased 12% from 130 to 146 mg/dl. In the 2 most recent surveys, self-reported "high cholesterol" increased from 17% to 27%, and self-reported lipid medication use by those with high cholesterol increased from 16% to 38%. Mean body mass index increased from 26 to 29 kg/m(2), and prevalence of obesity doubled and was significantly associated with increased TG. In conclusion, recent favorable trends in TC and LDL cholesterol are likely due to increased awareness of high cholesterol and the greater use of lipid-lowering drugs. However, countertrends in obesity and TG levels, if continued, will likely have a negative impact on cardiovascular disease in the future.
Little is known about the associations between non-response to follow-up surveys and mortality, or differences in these associations by socioeconomic position in studies with repeat data collections.
The Whitehall II study of socioeconomic inequalities in health provided response status from five data collection surveys; Phase 1 (1985-88, n = 10 308), Phase 5 (1997-99, n = 6533), and all-cause mortality to 2006. Odd-numbered phases included a medical examination in addition to a questionnaire.
Non-response to baseline and to follow-up phases that included a medical examination was associated with a doubling of the mortality hazard in analyses adjusted for age and sex. Compared with complete responders, responders who missed one or more phases, but completed the last possible phase before they died, had a 38% excess risk of mortality. However, those who missed one or more phases including the last possible phase before death had an excess risk of 127%. There was no evidence that these associations differed by socioeconomic position.
In studies with repeat data collections, non-response to follow-up is associated with the same doubling of the mortality risk as non-response to baseline; an association that is not modified by socioeconomic position.
This study examines the association between increases in antihypertensive pharmacotherapy and declines in stroke mortality among 96 US groups stratified by race, sex, age, metropolitan status, and region from 1962 to 1980.
Data on the prevalence of controlled hypertension and socioeconomic profiles were obtained from three successive national health surveys. Stroke mortality rates were calculated using data from the National Center for Health Statistics and the Bureau of the Census. The association between controlled hypertension trends and stroke mortality declines was assessed with weighted regression.
Prior to 1972, there was no association between trends in controlled hypertension and stroke mortality declines (beta = 0.04, P = .69). After 1972, groups with larger increases in controlled hypertension experienced slower rates of decline in stroke mortality (beta = 0.16, P = .003). Faster rates of decline were modestly but consistently related to improvements in socioeconomic indicators only for the post-1972 period.
These results do not support the hypothesis that increased antihypertensive pharmacotherapy has been the primary determinant of recent declines in stroke mortality. Additional studies should address the association between declining stroke mortality and trends in socioeconomic resources, dietary patterns, and cigarette smoking.
Although educational achievement is positively related to levels of high-density lipoprotein cholesterol (HDL-C) among White adults, there is an inverse association among Blacks. We assessed whether this interaction could be attributed to differences in the relation of education to correlates of HDL-C.
Cross-sectional analyses were based on data from 8391 White and 995 Black adults who participated in the Second National Health and Nutrition Examination Survey.
Associations between education and HDL-C levels varied from negative (Black men), to nearly nonexistent (White men and Black women), to positive (White women). Mean HDL-C levels were higher among Blacks than among Whites, but differences varied according to educational achievement. Among adults with less than 9 years of education, mean levels were 6 to 10 mg/dL higher among Blacks, but the radical difference was less than 1 mg/dL among adults with at least 16 years of education. About 20% to 40% of these differences could be accounted for by obesity, alcohol consumption, and other characteristics.
Because of the implications for coronary heart disease risk, consideration should be given to behavioral characteristics associated with the interaction between race and educational achievement.
The prevalence of diabetes mellitus was investigated in a sample of people aged 65 to 85 years, using a modified oral glucose tolerance test and 1985 WHO criteria. Of the sample of 861, 52 had previously been diagnosed diabetic; 583 consented to be tested and 19 were diabetic. The prevalence of previously diagnosed diabetes was 6.0 (95% CI 4.3 to 8.1) %, and the prevalence of previously undiagnosed diabetes was 3.3 (95% CI 2.0 to 5.0) %. The high prevalence of previously diagnosed diabetes might be due to the longstanding community diabetes care in the area studied.
Framingham Study findings suggest that total cholesterol (TC):High density lipoprotein cholesterol (HDL-C) ratio is a useful summary of the joint contribution of TC and HDL-C to coronary heart disease (CHD) risk. Information on the distribution of TC:HDL-C in the US population is limited to selected populations and the relationship of the ratio distribution and its correlates has received little attention.
TC/HDL-C ratios were examined in a representative sample of the United States adult population ages 20 to 74 years, between February 1976 and February 1980 during NHANES II, using stratification and multivariate regression analyses.
Age-adjusted mean ratios were higher in men compared with women and were higher in Whites compared with Blacks. White men had the highest TC/HDL-C mean ratios. These relationships remained after stratification by age, education, body mass index, alcohol use, cigarette smoking, and physical activity. Using multivariate analyses, the ratios were positively related to BMI, age, and smoking; and negatively related to female sex, alcohol use, being Black, and physical activity.
Using a ratio reference point of greater than or equal to 4.5 from the Framingham study, at least an estimated 44 million persons ages 25 to 74 years in the US were found to be at higher risk of developing coronary heart disease.
During 1981-1982, a cohort of elderly Japanese Americans living in Hawaii was recruited for an epidemiologic study of osteoporosis. The male subjects were simultaneously being examined for an epidemiologic study of heart disease. Baseline data collected from both the men and women at a previous heart disease examination were used to compare responders vs nonresponders. The target population for the osteoporosis study consisted of 1685 men and 1594 women. Of these, 1379 men (81.8%) and 1105 women (72.0%) participated in the initial osteoporosis examination. For each sex, nonrespondents were older and had higher systolic blood pressure levels than did the respondents. Male nonresponders had a higher stroke prevalence and more frequent recent use of vasodilator medicine. Female nonresponders had a less frequent history of having ever taken female hormones than did the responders. The responders and nonresponders were reasonably similar in other respects, as indicated by the comparison of more than 40 other variables. This suggests that nonresponse bias is probably not a major influence in exposure-disease associations in this osteoporosis cohort. We believe this is the first published report dealing with nonresponse characteristics in a cohort study of osteoporosis.
The recommended dietary allowance (RDA) of ascorbic acid for smokers was recently increased from 60 to 100 mg. To determine whether this new RDA for smokers is sufficient to reduce the risk of low serum ascorbic acid (AA) concentrations (LoC) to the same concentration as nonsmokers, we analyzed the dietary intakes and serum concentrations of AA in 11,582 adult respondents in the National Health and Nutrition Examination Survey (1976-1980). Serum AA concentrations and the risk of LoC (serum ascorbic acid levels less than 23 mumol/L) for smokers consuming different amounts of AA were compared with those for nonsmokers whose AA intake exceeded the RDA (60 mg). Serum AA concentrations were reduced, and risk of LoC increased, in smokers maintaining AA intakes greater than 60, 100, and 150 mg. Only smokers consuming greater than 200 mg AA/d had serum ascorbate concentrations and risk of LoC equivalent to nonsmokers meeting the RDA.
In 1982-83, 4,485 persons ages 65 or older were identified by a household census in East Boston, MA: 3,812 (85 percent) of them responded to a health and social status questionnaire. Data on age, sex, and living arrangements for the 4,485 eligible people were analyzed with respect to final participation status and reason for refusal or reluctance. The health and social status of reluctant and ready self-respondents were compared, and respondents-by-proxy were compared with self-respondents. Total participation rates were similar for both sexes and all ages, but the likelihood of interview by proxy increased with age, as did the likelihood of nonparticipation due to unavailability. Living alone or with other participants favored participation, and living with refusers or other nonrespondents increased the probability of refusal. While reluctant and ready self-respondents differed in only one health variable and two social variables, respondents-by-proxy differed from self-respondents in most variables tested. These analyses suggest an absence of major differences between self-respondents and refusers. Therefore, nonresponse bias is not likely to have a major impact on interpretation of the data obtained from participants in this study.
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