Content uploaded by Sandra D Anderson
Author content
All content in this area was uploaded by Sandra D Anderson
Content may be subject to copyright.
A preview of the PDF is not available
An exercise challenge for epidemiological studies of childhood asthma: validity and repeatability
Abstract and Figures
We assessed the validity, repeatability and practicality of a stan- dardized exercise challenge protocol for measuring airway responsiveness in epi- demiological studies of asthma in children aged 8-11 yrs. The construct validity of the exercise challenge was assessed by comparing response to exercise with other measures of asthma, i.e. wheeze frequency, diagnosed asth- ma, asthma medication use, atopy and urgent doctor visits (n=802), and by com- parison with response to histamine challenge (n=201). Repeatability was assessed by comparison of responsiveness to two exercise challenges within 3 days (n=113), and practicality was assessed by measurement of consent, compliance and through- put rates (n=802). There was a significant relationship between frequency of wheeze attacks and % fall in forced expiratory volume in one second (FEV1) to exercise. The correlation (r) between % fall in FEV1 to exercise challenge and dose-response ratio to hista- mine challenge was 0.59. The repeatability of the exercise challenge was ±12% fall in FEV1. Consent and compliance rates for exercise challenge were 78 and 99%, respectively, and the mean throughput rate was 45 children per school day for a team of seven researchers. In conclusion, this exercise challenge was found to have good validity and to be reliable and practical. Thus, this challenge could be used as a standardized epi- demiological tool to investigate the prevalence, aetiology and mechanisms of asthma.
Figures - uploaded by Sandra D Anderson
Author content
All figure content in this area was uploaded by Sandra D Anderson
Content may be subject to copyright.
... Some experts suggest that the threshold for severe EIB should be lowered to a 30% decrease in patients who receive treatment with inhaled corticosteroids. 1 The severity of EIB is related to airway eosinophilic inflammation in patients with asthma. 2 Exercise bronchoprovocation testing is regarded as an epidemiological tool to diagnose asthma in school-aged children and other populations. 3 The prevalence of EIB ranges from 40% to 90% of children with asthma, but is also detected in up to 30% of otherwise healthy children. 1,[3][4][5] Symptoms of EIB can be absent in children and often resolve spontaneously and go unreported. ...
... 3 The prevalence of EIB ranges from 40% to 90% of children with asthma, but is also detected in up to 30% of otherwise healthy children. 1,[3][4][5] Symptoms of EIB can be absent in children and often resolve spontaneously and go unreported. ...
Background/purpose:
Asthmatics with severe exercise-induced bronchoconstriction (EIB) are at high risk of exacerbations. The purpose of this study was to determine the prevalence, phenotypic, and laboratory determinants of severe EIB in Nigerian children with asthma.
Methods:
Children with controlled asthma (n = 101) underwent characterization and free-running exercise bronchoprovocation at a center in Nigeria. Lung function was measured before, then 5, 10, 15, and 30 minutes after 6 to 8 minutes exercise. Severe EIB was defined as ≥50% decrease in forced expired volume in 1 second (FEV1 ) from preexercise. Serum vitamin D and total antioxidant capacity were measured chromatographically. Factors predicting severe EIB were tested by logistic regression.
Result:
The sample was enriched in children with corticosteroid-naïve, mild intermittent asthma (71%). Thirteen percent had no EIB, 22% had severe and 65% nonsevere EIB. Children with severe EIB had higher preexercise FVC (105% vs 96%; P = .03) and FEV1 (98% vs 90%; P = .07), greater obesity (13.6% vs 1.3%; P = .02), more allergic rhinitis (AR) (63.6% vs 35.4%; P = .03), but less exposure to household pets (31.8% vs 72.2%; P = .003) compared to children with nonsevere EIB. Significant determinants (odds ratios/confidence intervals) for severe EIB were obesity = 12.3 (1.2-125.1), AR = 3.18 (1.19-8.52), blood eosinophilia = 1.005 (1.001-1.009), and hypovitaminosis D = 0.87 (0.81-0.93).
Conclusion:
In Nigerian children with asthma, severe EIB is common and associated with remediable comorbidities including type 2 pattern inflammation and vitamin D deficiency.
... In our experience, this pattern of behavior results in frequent transient episodes of airway narrowing, which usually do not constrain them from being physically active. The exercise challenge test has proven to be a valid model to investigate asthma with good repeatability [15], especially in moderate to severe asthmatic responses. It is therefore truly suitable to investigate potential mechanisms and treatments for asthma. ...
High flow nasal cannula (HFNC) therapy is a non-invasive oxygen delivery mode which is safe and well tolerated by adults and children with respiratory distress. HFNC is increasingly used in children with respiratory distress due to mucus retention, such as bronchiolitis and acute asthma. However, he effectiveness of this therapy in acute asthma has not been well researched. To evaluate HFNC for acute childhood asthma, we designed a randomized prospective crossover trial. In the trial, children aged 6–18 years, with a forced expiratory volume in one second (FEV1) lability of ≥30% during an exercise challenge test (ECT) are included. The time of fully recovered lung function within 10% of the baseline after peak fall of FEV1 is compared with and without HFNC therapy. A 50% reduction of recovery time during HFNC therapy compared to recovery time without HFNC is considered clinically relevant, with a power of 80% and a significance level of 5%. Secondly, the pressure used by the HFNC device to deliver the constant present flow is evaluated. A relationship between the measured pressure and the degree of recovery may reveal a working mechanism behind HFNC.
... Secondly, lack of a placebo arm disallows analysis of differences as a result of variability in response to an ECT. However, an ECT has a good repeatability 59 and all ECTs in this study were performed in a climate chamber under standardized conditions to further minimize climatic confounders. ...
Background
Exercise‐induced bronchoconstriction (EIB) is a frequent and highly specific symptom of childhood asthma. Inhaled corticosteroids (ICS) are the mainstay of controller therapy for EIB and asthma; however, a proportion of asthmatic children and adolescents is less responsive to ICS. We hypothesized that a single dose response to ICS could function as a predictor for individual long‐term efficacy of ICS.
Objective
To assess the predictive value of the bronchoprotective effect of a single‐dose beclomethasone dipropionate (BDP) against EIB for the bronchoprotective effect of 4 weeks of treatment, using an exercise challenge test (ECT).
Methods
Thirty‐two steroid‐naïve children and adolescents aged 6 to 18 years with EIB were included in this prospective cohort study. They performed an ECT at baseline, after a single‐dose BDP (200µg) and after 4 weeks of BDP treatment (100 µg twice daily) to assess EIB severity.
Results
The response to a single‐dose BDP on exercise‐induced fall in FEV1 showed a significant correlation with the response on exercise‐induced fall in FEV1 after 4 weeks of BDP treatment (r = .38, p = .004). A reduction in post‐exercise fall in FEV1 of more than 8% after a single‐dose BDP could predict BDP efficacy against EIB after 4 weeks of treatment with a positive predictive value of 100% (CI: 86.1–100%) and a negative predictive value of 29.4% (CI: 11.7%–53.7%).
Conclusion
We found that the individual response to a single‐dose BDP against EIB has a predictive value for the efficacy of long‐term treatment with BDP. This could support clinicians in providing personalized management of EIB in childhood asthma.
... Most studies of both EILO and EIB include adolescents (5,6,69). During these years the intensity of physical exercise often increases, and they approach their ventilation limits more often than earlier. ...
Complaints of breathlessness during heavy exercise is common in children and adolescents, and represent expressions of a subjective feeling that may be difficult to verify and to link with specific diagnoses through objective tests. Exercise-induced asthma and exercise-induced laryngeal obstruction are two common medical causes of breathing difficulities in children and adolescents that can be challenging to distinguish between, based only on the complaints presented by patients. However, by applying a systematic clinical approach that includes rational use of tests, both conditions can usually be diagnosed reliably. In this invited mini-review, we suggest an approach we find feasible in our everyday clinical work.
... No es reproducible como el examen realizado en laboratorio pero es mucho más sensible (21). Es útil como screening para BIE, aunque es complejo estandarizar las condiciones ambientales y cumplir con las medidas de seguridad que sugieren las guías internacionales (2,22). Las condiciones ambientales pueden aumentar el desarrollo y severidad de la BIE, por inhalación de alérgenos o poluyentes (4). ...
La prueba de provocación bronquial con ejercicio tiene como objetivo demostrar la presencia de hiperreactividad bronquial inducida por ejercicio, característica del asma bronquial. Su realización está bien estandarizada, requiriendo de condiciones ambientales especiales, preparación y esfuerzo submáximo del paciente. La respuesta se mide mediante espirometría, y se considera una prueba de provocación con ejercicio positivo, a una caída del volumen espirado al primer segundo (VEF1) del 10%. En este artículo se describen los elementos necesarios para facilitar la realización de este examen, acorde a normas y guías nacionales e internacionales.
Objective. There are few studies in clinically healthy subjects describing and quantifying exercise-induced bronchodilation (EIBd). This study aimed to describe and compare the magnitude and time course changes in post-exercise forced expired volume at the first second (FEV1) in healthy adolescents, younger adults, and older adults.
Methods. Adolescent (n = 73, aged 10-17 yrs), younger adult (n = 35, aged 18-25 yrs) and older adult (n = 25, aged 35-66 yrs) subjects with normal spirometry z-scores completed a maximal cardiopulmonary exercise test using the standardised exponential exercise test protocol on a cycle ergometer performed at stable temperature and humidity. Spirometry was performed pre-exercise and at 1-, 3-, 5-, and 10- minutes post-exercise to determine the percentage change in FEV1 compared to baseline. EIBd was defined as a ≥5% increase in post-exercise FEV1.
Results. Increases in FEV1 at one-minute post-exercise were observed in the adolescents (1.3%) and young adults (6.0%) with FEV1 returning to baseline after ten minutes. Compared to the adolescents, the older adults showed significantly greater and sustained increases in FEV1 at 1-, 3-, 5-, and 10- minutes post-exercise (6.4, 4.6, 4.7, and 3.8%, p < 0.05). At 1-minute post exercise a significantly greater proportion of younger adults (54%, p < 0.01) and older adults (64%, p < 0.01) demonstrated EIBd compared to the adolescent group (15%).
Conclusion. Healthy older adults had a higher prevalence, greater magnitude and more prolonged EIBd compared to healthy adolescent and young adult subjects.
Background: Chronic respiratory symptoms are common in Malawian adults and might be determined by lung development, growth and exposures in earlier life: alternative cooking methods, such as cleaner-burning cookstoves, have been proposed as a way to reduce biomassfuel smoke exposure and improve lung health. Tailored strategies for resource-limited settings are needed to improve the management of common childhood respiratory conditions.
Aims: 1. To explore the prevalence of non-communicable lung disease and air pollution associated determinants in children and adults in rural Malawi 2. Evaluate a novel task shifting approach to asthma management for children.
Methods: Within the same rural Chikhwawa communities, we conducted a prospective cohort study of adults, collecting respiratory questionnaire data, spirometry and personal air pollution exposure measurements at three timepoints over 3-years, and a cross-sectional study, collecting similar data from children aged 6-8 years at one timepoint. We also conducted a randomised-controlled trial and qualitative sub-study to evaluate the feasibility and effectiveness of a task shifting intervention, using non-medically trained asthma educators, on asthma outcomes. The intervention comprised detailed clinical assessment, optimisation of inhaled treatment, and asthma education delivered by lay educators. Asthma symptoms and exacerbations, spirometry and exhaled nitric oxide were assessed at 3-months.
Results: We recruited 1481 adults, mean (SD) age 43.8 (17.8) years, (654 with acceptable spirometry at ≥2 timepoints) and 804 children, mean (SD) age 7.1 (0.8) years, (522 with acceptable spirometry) in Chikhwawa. Forced expiratory volume in 1 second (FEV1) and Forced
Vital Capacity (FVC) decline were 30.9 ml/year (95% confidence interval (CI): 21.6-40.1) and 38.3ml/year (95% CI: 28.5-48.1), respectively: comparable to natural age-related decline seen in healthy non-smokers in high-income settings. Lung function z-scores, referencing Global Lung Initiative African-American predicted values, were similar in children and adults and we found no evidence of an association between personal air pollution exposure and lung function or respiratory symptoms. Secondary analysis of a sub-group of children from households previously enrolled in a cookstove trial suggested a potential benefit: children from intervention households had a lower carboxyhaemoglobin level and higher FVC z-scores compared to controls.
We recruited 120 asthmatic children at a tertiary hospital in urban Blantyre; 59 received the intervention, 61 continued with standard care in the outpatient clinic. At 3-months, we found a clinically and statistically significant improvement in the primary outcome: asthma control in intervention vs standard care group (increase in mean (SD) cACT score of 2.7 (2.8) vs 0.6 (2.8), p<0.001). In addition, fewer children receiving the intervention required emergency health care (7.3% vs 23.7%, p=0.03) or missed school (20.0% vs 61.0%, p<0.001) due to exacerbations. Children and carers described the positive impact of asthma education on their knowledge levels and increased confidence to self-manage symptoms.
Implications: Our findings from Chikhwawa suggest that lung function deficits seen in adults are present in childhood, and that early life influences are likely an important contributor to adult lung health. Future research should consider public health interventions addressing multiple adverse risk factors encountered in utero and early childhood.
Task shifting asthma education roles resulted in improved asthma outcomes and high levels of patient satisfaction, suggesting this could be an effective strategy in resource-limited settings.
Further research is needed to assess the wider application of this approach across all levels of health facility.
Background
Bronchial hyper-responsiveness (BHR) is the hallmark of bronchial asthma, characterized by clinical features of cough, wheeze, breathlessness and chest tightness which are confirmed by spirometry showing obstructive pattern and reversibility to bronchodilators. In individuals having features of bronchial asthma but normal spirometry, demonstration of BHR with bronchial challenge test (direct or indirect) confirms/ rules out the diagnosis. The aim of this study was to assess BHR in patients (methacholine challenge) with a history suggestive of bronchial asthma but normal spirometry and its role in diagnosis of bronchial asthma.
Methods
This study was conducted at tertiary care respiratory center. Patients having clinical features of bronchial asthma but spirometry not confirming obstructive disorder and or reversibility were included in the study. After written consent, methacholine challenge test with methacholine chloride and exercise spirometry was done in all patients as per the American Thoracic Society protocol.
Results
A total of 50 (n) patients were included in the study. Among them, 42 patients had clinical features suggestive of bronchial asthma but having normal spirometry and eight patients were diagnosed as they had bronchial asthma in the past but asymptomatic and off drugs were included in the study. At PC20 4mg/ml 32 (64%) patients had a positive test, 28(66%) symptomatic patients and four (50%) asymptomatic asthmatics. There were no significant side effects with methacholine test.
Conclusion
Airway hyper-responsiveness is an important aspect of bronchial asthma and its demonstration with bronchial challenge (direct and indirect) test is an important diagnostic tool. Methacholine challenge test is a safe procedure to perform under supervision.
Exercise and hyperventilation are two stimuli which are known to provoke acute airway narrowing in patients with clinically recognised asthma. The sensitivity of a subject to the effects of exercise or hyperventilation is often expressed by symptoms of cough, dyspnea or wheezing and frequently occur as the first sign of asthma, particularly in childhood.
The main intent of this paper is to introduce a new statistical procedure for testing a complete sample for normality. The test statistic is obtained by dividing the square of an appropriate linear combination of the sample order statistics by the usual symmetric estimate of variance. This ratio is both scale and origin invariant and hence the statistic is appropriate for a test of the composite hypothesis of normality. Testing for distributional assumptions in general and for normality in particular has been a major area of continuing statistical research-both theoretically and practically. A possible cause of such sustained interest is that many statistical procedures have been derived based on particular distributional assumptions-especially that of normality. Although in many cases the techniques are more robust than the assumptions underlying them, still a knowledge that the underlying assumption is incorrect may temper the use and application of the methods. Moreover, the study of a body of data with the stimulus of a distributional test may encourage consideration of, for example, normalizing transformations and the use of alternate methods such as distribution-free techniques, as well as detection of gross peculiarities such as outliers or errors. The test procedure developed in this paper is defined and some of its analytical properties described in ? 2. Operational information and tables useful in employing the test are detailed in ? 3 (which may be read independently of the rest of the paper). Some examples are given in ? 4. Section 5 consists of an extract from an empirical sampling study of the comparison of the effectiveness of various alternative tests. Discussion and concluding remarks are given in ?6. 2. THE W TEST FOR NORMALITY (COMPLETE SAMPLES) 2 1. Motivation and early work This study was initiated, in part, in an attempt to summarize formally certain indications of probability plots. In particular, could one condense departures from statistical linearity of probability plots into one or a few 'degrees of freedom' in the manner of the application of analysis of variance in regression analysis? In a probability plot, one can consider the regression of the ordered observations on the expected values of the order statistics from a standardized version of the hypothesized distribution-the plot tending to be linear if the hypothesis is true. Hence a possible method of testing the distributional assumptionis by means of an analysis of variance type procedure. Using generalized least squares (the ordered variates are correlated) linear and higher-order
In order to explore the relationship between bronchial hyperresponsiveness (BHR) to inhaled histamine, respiratory symptoms and diagnosed asthma in children, we undertook a cross-sectional study of 2363 Australian schoolchildren aged 8-11 years. The methods used included a self-administered questionnaire to parents, which was shown to have a high degree of repeatability, and a histamine inhalation test to measure bronchial responsiveness (BR). The study showed that 17.9% of children had BHR, defined as a 20% fall in FEV1 at a provoking dose of histamine (PD20 FEV1) of less than 7.8 mumol. The distribution of PD20 FEV1 appeared to be continuous. Most children with PD20 FEV1 values less than 1.0 mumol had symptoms of asthma. However, 6.7% of children had BHR without symptoms or a previous diagnosis of asthma and 5.6% had had a diagnosis of asthma but had no BHR. Although there was a good association between BHR and respiratory symptoms, questionnaire data of wheeze and diagnosed asthma do not reflect accurately the level of BHR in the community. We conclude that cross-sectional studies of BR to identify children with BHR probably do not reflect the prevalence of asthma in populations of children. However, the strong association between BHR and symptoms, particularly in children with severe and moderate BHR, suggests that measurements of BR in populations are useful for defining a group of children whose airways behave differently from those of the majority. Prospective studies are needed to define the level of BHR that is associated with important sequelae.
Incluye bibliografía e índice Reimprisión en 1992.
It is 15 yr since Jones et al.’ first described the effects of isoproterenol on the postexercise increase in airway resistance in patients with asthma. Studies of the incidence, severity, and reproducibility of exercise-induced asthma (EIA) have established that in 70% to 75% of patients with clinically recognized asthma, the postexercise fall in peak expiratory flow rate (PEFR) or forced expiratory volume in 1 set (FEV,) exceeds 10% of the preexercise value.2. I’ Changes in lung mechanics and blood gas tensions seen during EIA are similar to those observed in patients with asthma provoked by other stimuli.“. Irk II Consequently EIA has been used as a model for the investigation of drugs used in treatment of asthmatics. During the past 10 yr many studies have been carried out to determine the effect of a wide variety of pharmacologic agents on EIA. The drug groups studied include
An epidemiological study was undertaken to determine the prevalence of asthma in young urban and rural black (Xhosa) children. One thousand three hundred and seventy five children were studied, 694 from a Cape Town african township and 671 from a rural area in Transkei. The exercise tolerance test which required free range running at maximum effort for 6 min was used to identify asthmatic subjects. A fall of 15% or more in the post‐exercise FEV 1 and PEFR values was regarded as a positive result. Twenty‐three children were found to be asthmatic, twenty‐two from the city area, but only one from the country, giving a prevalence figure for asthma of 3.17% in the first group and 0.14% for the second. Possible reasons for these differences are discussed.
The exercise tolerance test was found to be a useful tool for epidemiological studies of asthma.
Patients with asthma frequently develop acute, reversible, and usually self-terminating airway obstruction after or near the end of strenuous muscle exercise.‘. 2 This response may require quantitative assessment because of the poor correlation that exists between historical and laboratory evidence for exercise-induced bronchospasm (EIB),:’ and it can be used to provoke airway obstruction in patients with suspected, but unconfirmed asthma. During the past few years a number of tests have been developed for the assessment of EIB. The increased utilization of such procedures makes standardization of the methods timely and necessary so that safe and adequate techniques are used and so that results obtained in different laboratories can be compared.
Twenty-five normal and 105 asthmatic children were exercised on a treadmill. Pulmonary function was assessed before and after exercise. The maximum fall from the resting value in normal subjects depended on the test used: PEFR 12.5%; FEV1 10%; MMEF 26%; V50 30%; V25 33%. Using these criteria, PEFR and FEV1 detected 99% of those asthmatic children who had a positive exercise response. The largest fall from the resting value was seen with the MMEF, but this test detected only 70% of the positive responders. The pre-exercise function did not affect the severity of the response but did have an effect on the incidence of exercise-induced bronchospasm.