Abstract
BackgroundAdministrative patient registers are often used to estimate morbidity in epidemiological studies. The validity of register data is thus important. This study aims to assess the positive predictive value of myocardial infarction and stroke registered in the Danish National Patient Register, and to examine the association between cardiovascular risk factors and cardiovascular disease based on register data or validated diagnoses in a well-defined diabetes population.MethodsWe included 1533 individuals found with screen-detected type 2 diabetes in the ADDITION-Denmark study in 2001–2006. All individuals were followed for cardiovascular outcomes until the end of 2014. Hospital discharge codes for myocardial infarction and stroke were identified in the Danish National Patient Register. Hospital medical records and other clinically relevant information were collected and an independent adjudication committee evaluated all possible events. The positive predictive value for myocardial infarction and stroke were calculated as the proportion of cases recorded in the Danish National Patient Register confirmed by the adjudication committee.ResultsThe positive predictive value was 75% (95% CI: 64;84) for MI and 70% (95% CI: 54;80) for stroke. The association between cardiovascular risk factors and incident cardiovascular disease did not depend on using register-based or verified diagnoses. However, a tendency was seen towards stronger associations when using verified diagnoses.ConclusionsOur results show that studies using only register-based diagnoses are likely to misclassify cardiovascular outcomes. Moreover, the results suggest that the magnitude of associations between cardiovascular risk factors and cardiovascular outcomes may be underestimated when using register-based diagnoses.
Highlights
Administrative patient registers are often used to estimate morbidity in epidemiological studies
A recent Danish study evaluating more than 2000 discharge codes for cardiovascular diagnoses in 2010–2012 found that the positive predictive value (PPV) of cardiovascular disease based on hospital records as the reference standard varied according to diagnosis; PPV for first time myocarditis:64% and for first time myocardial infarction (MI):97% [12]
We identified 17 women with MI diagnosis in the Danish National Patient Register (DNPR); 88% were confirmed by the adjudication committee
Summary
Administrative patient registers are often used to estimate morbidity in epidemiological studies. This study aims to assess the positive predictive value of myocardial infarction and stroke registered in the Danish National Patient Register, and to examine the association between cardiovascular risk factors and cardiovascular disease based on register data or validated diagnoses in a well-defined diabetes population. Previous studies of the positive predictive value (PPV) of cardiovascular diseases in the DNPR have generally found fair agreement between the registered codes and hospital records [4,5,6,7,8,9,10,11,12,13]. A recent Danish study evaluating more than 2000 discharge codes for cardiovascular diagnoses in 2010–2012 found that the PPV of cardiovascular disease based on hospital records as the reference standard varied according to diagnosis; PPV for first time myocarditis:64% and for first time myocardial infarction (MI):97% [12]. Besides discharge summaries and medical records, we included electrocardiographs, laboratory tests, post-mortems (autopsies) and death certifications in the determination of the reference diagnosis
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
