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ICD-10 codes for dementia and distribution of registered dementia diagnoses among the 197 random- ly selected patients
Source publication
The validity of dementia diagnoses in the Danish nationwide hospital registers was evaluated to determine the value of these registers in epidemiological research about dementia.
Two hundred patients were randomly selected from 4,682 patients registered for the first time with a dementia diagnosis in the last 6 months of 2003. The patients' medical...
Contexts in source publication
Context 1
... population included both inpatients and outpa- tients from all public hospitals in the entire country. ICD-10 codes for Alzheimer's disease (AD), vascular dementia (VaD), fronto- temporal dementia (FTD), and dementia without specification were used ( table 1 ). ...
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Citations
... However, previous validation studies have shown that for dementia cases in Danish registers the diagnoses are very specific and represent more severe cases of dementia. 32 A second limitation is the inclusion of women only (by nature of our nurse cohort design) as they have a higher risk of developing AD, 54,55 but little is known on whether sex mediates the association between air pollution and the incidence of dementia. ...
INTRODUCTION
We examined the association of long‐term exposure to air pollution and road traffic noise with dementia incidence in the Danish Nurse Cohort.
METHODS
Female nurses were followed for dementia incidence (hospital contact or medication prescription) from 1993/1999 to 2020. Air pollution and road traffic noise levels were estimated at nurses’ residences, and their associations with dementia were examined using Cox regression models.
RESULTS
Of 25,233 nurses 1409 developed dementia. Particulate matter with a diameter of ≤2.5 µm (PM2.5) was associated with dementia incidence, after adjusting for lifestyle, socioeconomic status, and road traffic noise (hazard ratio [95% confidence interval] 1.35 [1.15–1.59] per interquartile range of 2.6 µg/m³). There was no association of PM2.5 with dementia in physically active nurses. Association with road traffic noise diminished after adjusting for PM₂.₅ (1.02 [0.93–1.11] per 7.6 dB).
DISCUSSION
Long‐term exposure to air pollution increases risk of dementia, and physical activity may moderate this risk.
Highlights
Long‐term exposure to air pollution was associated with increased risk of dementia among female nurses from the Danish Nurse Cohort.
Association of air pollution with dementia was independent of road traffic noise.
Association of road traffic noise with dementia diminished after adjusting for air pollution.
Physical activity moderated adverse effects of air pollution on dementia.
... Primary diagnoses were obtained from the Danish National Patient Register [9] and the mentioned ICD-10 codes were carefully checked used as guideline the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition, Text Revision (DSM-5-TR) for major and mild neurocognitive disorders [15] and the recommended codes by Allan et al. [16]. The validity of major CI diagnoses in the Danish National Patient Register has been previously assessed and it was found to have positive predictive values more than 80% [17,18]. ...
... In addition, the available data only included diagnoses based on clinical admissions for major and mild CI, often established in outpatient clinics. It is essential to acknowledge that while the validation study conducted by Phung et al. [17] demonstrated higher validity in diagnosing major CI, it may not fully capture the complexities inherent in real-world diagnostic scenarios and their associated validity. ...
Introduction
The prevalence of major and mild cognitive impairment (CI) in type-2 diabetes older patients is 15–25% and 30–60%, respectively, thus affecting quality of life and health outcomes. There is, therefore, the need of head-to-head studies aiming at identifying the optimal treatment for individuals with type-2 diabetes at increased risk of mild and major CI. This study focuses on the risk of developing mild and major CI in Danish patients treated with dipeptidyl peptidase-4 inhibitors (DPP-4i) and glucagon-like peptide-1 analogues (GLP-1a) using administrative and healthcare registers.
Methods
An active comparator design with a 3-year follow-up period was used. The main outcome was the hospital admission with a diagnosis of mild CI or major CI. Multivariate Cox Regression analysis was performed using the high-dimensional propensity score to obtain adjusted Hazard Ratio (HR) estimates. Inverse probability of treatment weighting (IPTW) and marginal structured model were used to calculate risk differences while accounting for the variations of confounders throughout the follow-up period.
Results
Our results show a significant higher risk of major CI between DPP-4i and GLP-1a in unadjusted [HR (95% CI) = 3.13 (2.45–4.00), p < 0.001] and adjusted analyses [HR (95% CI) = 1.58 (1.22–2.06), p = 0.001]. No statistically significant differences were observed for mild CI. IPTW resulted stable throughout the follow-up period. Marginal structure modeling (β (95% CI) = 0.022 (0.020–0.024), p < 0.001) resulted in a higher risk of major CI for DPP-4i when compared to GLP-1a.
Discussion
DPP-4i was associated with an increased risk of developing major CI when compared to GLP-1a among older individuals with type-2 diabetes.
... In two other studies using Danish nationwide hospital registers, diagnostic codes accurately identified AD in only 60-80% of cases, with a PPV ranging from 0.78 to 0.81. 13,14 In a US based study, Taylor et al. found that the AD diagnostic codes in Medicare claims data only have a sensitivity of 0.64 and a specificity of 0.96 for identifying AD. 15 Besides diagnostic codes, EHR data element like AD-related medications have also been used to identify AD patients. Tjandra et al. developed and validated an AD cohort discovery tool using a rule set that includes encounters, diagnosis codes, medications, and procedure codes (e.g., for psychological/cognitive testing), achieving moderate performance with an F1-score of 0.73, a PPV of 0.77, and a sensitivity of 0.70 in a Michigan Alzheimer's Disease Research Center (ADRC) cohort. ...
... Third, our final CP algorithm is simple (i.e., "with at least 2 AD diagnosis, and with keywords in AD encounters"), making it readily applied to other EHR systems. Further, compared with previous studies, [12][13][14][15][16] our algorithm demonstrated superior performance, achieving higher sensitivity, while maintaining comparable PPV. Our final algorithm achieved a perfect sensitivity on the testing dataset, indicating that it can correctly identify all patients who truly have AD. ...
INTRODUCTION: Alzheimer's Disease (AD) are often misclassified in electronic health records (EHRs) when relying solely on diagnostic codes. This study aims to develop a more accurate, computable phenotype (CP) for identifying AD patients by using both structured and unstructured EHR data.
METHODS: We used EHRs from the University of Florida Health (UF Health) system and created rule-based CPs iteratively through manual chart reviews. The CPs were then validated using data from the University of Texas Health Science Center at Houston (UT Health) and the University of Minnesota (UMN).
RESULTS: Our best-performing CP is "patient has at least 2 AD diagnoses and AD-related keywords" with an F1-score of 0.817 at UF, and 0.961 and 0.623 at UT Health and UMN, respectively.
DISCUSSION: We developed and validated rule-based CPs for AD identification with good performance, crucial for studies that aim to use real-world data like EHRs.
... The Danish National Patient Registry (DNPR) was established in 1977 and holds, on an individualized basis, information of all hospital contacts including hospitalization and outpatient visits, e.g., admission date and medical diagnosis, as given by the International Classification of Diseases (ICD) 10 th revision codes [19]. Regarding AD diagnosis, DNPR has previously been validated and found suitable for use in register-based studies [20]. ...
... The registers do not hold information regarding race and lifestyle factors such as smoking, blood glucose, or blood pressure values, and therefore made it impossible for us to adjust for these possible confounders. Diagnosis of AD in the DNPR has previously been evaluated to have high validity, although overall, 30% of AD diagnosis were misclassified as unspecific dementia [20] To compensate for this, we only included persons with AD if the diagnosis was made at a specialized department. ...
Background: Retinal neurodegeneration is evident in early diabetic retinopathy (DR) which may be associated with other neurodegenerative diseases like Alzheimer’s disease (AD). Objective: To investigate diabetes and DR as a risk marker of present and incident AD. Methods: A register-based cohort study was performed. We included 134,327 persons with diabetes above 60 years of age, who had attended DR screening, and 651,936 age- and sex-matched persons without diabetes. Results: At baseline, the prevalence of AD was 0.7% and 1.3% among persons with and without diabetes, respectively. In a multivariable regression model, persons with diabetes were less likely to have AD at baseline (adjusted OR 0.63, 95% CI 0.590.68). During follow-up, incident AD was registered for 1473 (0.35%) and 6,899 (0.34%) persons with and without diabetes, respectively. Compared to persons without diabetes, persons with diabetes and no DR had a lower risk to develop AD (adjusted HR 0.87, 95% CI 0.810.93), while persons with diabetes and DR had higher risk of AD (adjusted HR 1.24, 95% CI 1.081.43). When persons with diabetes and no DR were used as references, a higher risk of incident AD was observed in persons with DR (adjusted HR 1.34, 95% CI 1.181.53). Conclusion: Individuals with diabetes without DR were less likely to develop AD compared to persons without diabetes. However, individuals with DR had a 34% higher risk of incident AD, which raise the question whether screening for cognitive impairment should be done among individuals with DR.
... The included ICD-10 for dementia and Anatomical Therapeutic Chemical (ATC) codes for dementia medication are shown in Supplemental Table S2. The ICD-10 codes for Alzheimer's disease, vascular dementia, frontotemporal dementia, and dementia unspecified have been validated and found to be correct in 85.8% of cases within the DNPR [32]. ...
... There is a risk that patients without the relevant diagnostic work-out may be diagnosed with dementia based on symptoms reported by relatives or clinical presentation. This is supported by a study by Phung et al. that conducted a medical chart review and patient interviews and found dementia diagnosed in 2003 to be correct in the DNPR in 85.8% of the cases [32]. In the remaining cases, data was insufficient in 9.1% and dementia was ruled out in 5.1%. ...
... 27 The validity of dementia syndrome diagnoses in Danish hospital registers is high. 32 Prescriptions with dementiaspecific medication (for Alzheimer's disease, Lewy body dementia, and ...
... In the context of PPIs being among the most prescribed drugs worldwide and with high prevalence of inappropriate use, further elucidation of long-term safety in relation to dementia as well as interventions promoting appropriate use is an important public health matter. [2][3][4][5][6][8][9][10] Strengths of the study include the large nationwide study population, long follow-up period, highly valid dementia diagnoses, 32 However, since our main finding was increased risk, we do not expect the competing death risk to have impacted the overall interpretation. ...
... Second, we could not differentiate between vascular dementia and neurodegenerative etiologies of dementia due to low validity of non-AD subtype diagnoses. 32 Considering the previously reported positive association between PPI use and risk of stroke, 38 the observed association with all-cause dementia could be reflecting the association with stroke. However, the sensitivity analysis restricted to individuals without stroke supported the main results, making it improbable that our findings are entirely explained by stroke as an intermediary on the causal pathway. ...
INTRODUCTION
Proton pump inhibitors (PPIs) may increase dementia risk. However, it is currently unknown whether timing of exposure or age at dementia diagnosis influence the risk.
METHODS
We assessed associations between cumulative PPI use and dementia at different ages in a nationwide Danish cohort of 1,983,785 individuals aged 60 to 75 years between 2000 and 2018.
RESULTS
During follow‐up, there were 99,384 all‐cause dementia incidences. Incidence rate ratio (IRR) of dementia with PPI ever‐use compared with never‐use was 1.36 (95% CI, 1.29 to 1.43) for age 60 to 69 years at diagnosis, 1.12 (1.09 to 1.15) for 70 to 79 years, 1.06 (1.03 to 1.09) for 80 to 89 years, and 1.03 (0.91 to 1.17) for 90+ years. Longer treatment duration yielded increasing IRRs. For cases below 90 years, increased dementia rate was observed regardless of treatment initiation up to >15 years before diagnosis.
DISCUSSION
Regardless of timing of treatment initiation, PPI use was associated with increased dementia rate before age 90 years. Dementia rates increased with younger age at diagnosis.
Highlights
After following 1,983,785 individuals for a median of 10 years, 99,384 developed dementia
PPIs were used by 21.2% of cases and 18.9% of controls
PPI use was associated with increased dementia rate regardless of time of treatment onset
Magnitude of associations increased with younger age at diagnosis
PPI use was not associated with dementia occurring after age 90 years
... The major strengths of this study are as follows: First, we utilised the well-validated, nationwide Danish registers that allowed for analyses of the entire population, including people of all ages with full information on exposure (PCR test, hospitalisation), outcomes (neurological disorders diagnosed in an inpatient or outpatient setting, including emergency room visits), and important individual covariates such as age, sex, comorbidity, socioeconomics, and similar data for individuals' parents). Second, the Danish registers are wellknown for their high validity regarding the main diagnostic disease categories [16][17][18][19][20][21][22][23][24] , thus the results from this nationwide study are representative of the population of Denmark. Third, the models were adjusted for important confounders and the results were robust also in the sensitivity analyses. ...
Hospitalisation with COVID-19 is associated with an increased risk of neurological sequelae; however, representative nationwide studies comparing to other infections with similar severity and also including milder SARS-CoV-2 infections have been lacking. Using the nationwide Danish registers including all SARS-CoV-2 PCR test results and hospitalisations between March 1, 2020, and December 31, 2021, we estimate the risk of any first neurological disorder diagnosed in inpatient, outpatient, or emergency room settings. We show that positive tests increase the rate of neurological disorders by a hazard ratio of 1.96 (95% confidence interval: 1.88–2.05) compared to individuals not tested and by a hazard ratio of 1.11 (95% confidence interval: 1.07-1.16) compared to individuals with negative tests only. However, there is no evidence that the risk of neurological disorders is higher for individuals who test positive compared to non-COVID-19 infections treated with anti-infective medication. The risk of neurological disorders is increased after COVID-19-hospitalisation compared to no COVID-19 hospital admission; however, these risks are comparable to hospitalisation with other respiratory infections (P value 0.328). In conclusion, COVID-19 is associated with an increased risk of neurological disorders, but no more than that observed after other infections of similar severity.
... Only 26% of our cases were registered with Alzheimer's disease compared with an expected proportion of around 70%. 28 Despite the underregistration of Alzheimer's disease, mainly due to use of unspecific dementia diagnoses in Danish hospital registries, the diagnoses of Alzheimer's disease have shown to have a positive predictive value of 81%, making these diagnoses appropriate for epidemiological research. 27 We do not expect the potential proportion of false positive diagnoses of all cause dementia or Alzheimer's disease to be differentially distributed among women who received or did not receive hormone treatment because most women who had treatment had their last treatment day more than eight years before the index date. As such, this means that exposure status would not have been likely to have affected the likelihood of dementia diagnosis. ...
... We were not able to isolate vascular dementia from other types of dementia due to low validity of vascular dementia diagnosis. 27 Use of oral menopausal hormone therapy is an acknowledged risk factor for stroke and could explain the positive association between menopausal hormone therapy use and dementia. 29 However, we excluded women with stroke events, therefore our findings are unlikely to represent any association between systemic hormone therapy and stroke. ...
Objectives:
To assess the association between use of menopausal hormone therapy and development of dementia according to type of hormone treatment, duration of use, and age at usage.
Design:
Nationwide, nested case-control study.
Setting:
Denmark through national registries.
Participants:
5589 incident cases of dementia and 55 890 age matched controls were identified between 2000 and 2018 from a population of all Danish women aged 50-60 years in 2000 with no history of dementia or contraindications for use of menopausal hormone therapy.
Main outcome measures:
Adjusted hazard ratios with 95% confidence intervals for all cause dementia defined by a first time diagnosis or first time use of dementia specific medication.
Results:
Compared with people who had never used treatment, people who had received oestrogen-progestogen therapy had an increased rate of all cause dementia (hazard ratio 1.24 (95% confidence interval 1.17 to 1.33)). Increasing durations of use yielded higher hazard ratios, ranging from 1.21 (1.09 to 1.35) for one year or less of use to 1.74 (1.45 to 2.10) for more than 12 years of use. Oestrogen-progestogen therapy was positively associated with development of dementia for both continuous (1.31 (1.18 to 1.46)) and cyclic (1.24 (1.13 to 1.35)) regimens. Associations persisted in women who received treatment at the age 55 years or younger (1.24 (1.11 to 1.40)). Findings persisted when restricted to late onset dementia (1.21 (1.12 to 1.30)) and Alzheimer's disease (1.22 (1.07 to 1.39)).
Conclusions:
Menopausal hormone therapy was positively associated with development of all cause dementia and Alzheimer's disease, even in women who received treatment at the age of 55 years or younger. The increased rate of dementia was similar between continuous and cyclic treatment. Further studies are warranted to determine whether these findings represent an actual effect of menopausal hormone therapy on dementia risk, or whether they reflect an underlying predisposition in women in need of these treatments.
... These issues would naturally affect our estimates of socioeconomic disparities. However, earlier studies have not found evidence of systematic misclassification; reported diagnoses of psychiatric and somatic conditions have been validated with good results [95,[97][98][99][100][101][102]. ...
Background
Real-world information on socioeconomic differences within and between chronic conditions represents an important data source for treatments and decision-makers executing and prioritising healthcare resources.
Aims
The aim of this study was to estimate the prevalence and mean of socioeconomic disparities from educational, income, and socioeconomic positions of 199 chronic conditions and disease groups, including sex and age group estimates, for use in planning of care services and prioritisation, by healthcare professionals, decision-makers and researchers.
Methods
The study population includes all Danish residents 16 years and above, alive on 1 January 2013 (n = 4,555,439). The data was established by linking seven national registers encompassing educational achievements, incomes, socioeconomic positions, hospital- and general practice services, and filled-in out-of-hospital prescriptions. The health register data were used to identify the 199+ chronic conditions. Socioeconomic differences were primarily measured as differences in educational prevalence levels from low to high educational achievements using a ratio. Furthermore, multiple binary logistic regression models were carried out to control for potential confounding and residual correlations of the crude estimates.
Results
The prevalence of having one or more chronic conditions for patients with no educational achievement was 768 per thousand compared to 601.3 for patients with higher educational achievement (ratio 1.3). Across disease groups, the highest educational differences were found within disease group F–mental and behavioural (ratio 2.5), E–endocrine, nutritional and metabolic disease (ratio 2.4), I–diseases of the circulatory system (ratio 2.1) and, K–diseases of the digestive system (ratio 2.1). The highest educational differences among the 29 common diseases were found among schizophrenia (ratio 5.9), hyperkinetic disorders (ratio 5.2), dementia (ratio 4.9), osteoporosis (ratio 3.9), type 2 diabetes (ratio 3.8), chronic obstructive pulmonary disease COPD (ratio 3.3), heart conditions and stroke (ratios ranging from 2.3–3.1).
Conclusions
A nationwide catalogue of socioeconomic disparities for 199+ chronic conditions and disease groups is catalogued and provided. The catalogue findings underline a large scope of socioeconomic disparities that exist across most chronic conditions. The data offer essential information on the socioeconomic disparities to inform future socially differentiated treatments, healthcare planning, etiological, economic, and other research areas.
... Diagnoses of all-cause dementia and Alzheimer's disease were obtained from the Danish National Patient Registry, which has recorded hospital admission since 1977, and outpatient visits since 1995. The positive predictive value of all-cause dementia and Alzheimer's disease coded in the registry is 86% and 81%, respectively [25]. We identified diagnoses according to the World Health Organization International Classification of Diseases 8th edition (ICD-8) until the end of 1993 and 10th edition (ICD-10) thereafter. ...
... m 2 was associated with increased risk of all-cause dementia (1. 25 Spline models showed no clear association between eGFR levels and risk of all-cause dementia or Alzheimer's disease (Supplemental Fig. 4). ...
Whether impaired kidney function is associated with increased risk of developing dementia is unclear. We investigated the association between estimated glomerular filtration rate (eGFR) and dementia. Using a triangulation approach, we performed (1) a prospective study in 90,369 Danes from the Copenhagen General Population Study (CGPS), (2) a meta-analysis in 468,699 Scandinavians (including CGPS) and (3) a two-sample Mendelian randomization study in 218,792-1,004,040 Europeans using summary data from largest publicly available genome wide association studies (GWASs). During up to 15 years of follow-up (CGPS), 2,468 individuals developed dementia. Age and sex standardized percentile of eGFR below versus above the median conferred a multifactorially adjusted hazard ratio of 1.09 (95% confidence interval: 1.01–1.18). In meta-analysis, random-effects risk of dementia was 1.14 (1.06–1.22) for mildly decreased eGFR (60–90 mL/min/1.73 m²), 1.31 (0.92–1.87) for moderately decreased eGFR (30–59 mL/min/1.73 m²) and 1.91 (1.21–3.01) for severely decreased eGFR (< 30 mL/min/1.73 m²), compared to reference eGFR (> 90 mL/min/1.73 m²). Using directly comparable eGFR measures (log[eGFR] scaled to one standard deviation, as well as eGFR below versus above 60 mL/min/1.73 m²), we found no association with risk of dementia in observational CGPS or in Mendelian randomization analyses. In conclusion, impaired kidney function was associated with modestly increased risk of developing dementia. This was not supported by causal, genetic analyses using a Mendelian randomization approach. However, future stronger genetic instruments for kidney function and larger GWASs with more dementia cases, particularly for the vascular dementia subtype, warrant a re-evaluation of the causal hypothesis.
