World War II cohorts and diabetes mellitus, coronary heart disease and cerebrovascular disease later in life: An observational cohort study based on German claims data

BackgroundThis study applied a data-driven approach to explore whether being born during or around World War II affects the risk of morbidity later in life. MethodsIncident diagnoses were explored for diabetes (ICD-10 code E10-E14; 75,487 persons/12,905 incident cases), cerebrovascular disease (CeVD; I6; 79,829/11,664), and coronary heart disease (CHD; I20-I25; 89,657/11,116) for birth cohorts 1935-1950, using German health-claims data from 2004-2015. The data include quarterly information of the inpatient and outpatient treatment. We applied recursive partitioning methods with the aim of splitting the sample into birth cohorts with different risk profiles in terms of the incidence of diabetes, CeVD, and CHD. We performed Cox proportional hazard models to explore the transition into diabetes, CeVD, and CHD, accounting for birth cohort and gender. We used the median cut-points from the recursive partitioning analysis on the birth cohort indicator to define linear splines and present the yearly slopes of the linear splines. ResultsBased on the results from recursive partitioning method we defined four groups of birth cohorts depending on the disease of interest (diabetes: 1/35-10/37, 11/37-11/41, 12/41-10/44, 11/44-12/50; CHD: 1/35-5/37, 6/37-4/41, 10/44-12/50; CeVD: 1/35-6/37, 7/37-6/40, 7/40-12/43, 1/44-12/50). We found a general decline in cohort incidence for all three diseases, however, there was a discontinuation for diabetes among birth cohorts 12/41-10/44 (yearly slope=-0.01, p=0.584), and a deceleration for cohorts 11/44-12/50 for CeVD. ConclusionsWe identified risk periods associated with WWII that interfered with the cohort decline in the risk of diabetes and CeVD, stressing the importance of a beneficial early-life environment. Availability of dataThe scientific research institute of the AOK (WIdO) has strict rules regarding data sharing because of the fact that health claims data are a sensible data source and have ethical restrictions imposed due to concerns regarding privacy. Anonymized data are available to all interested researchers upon request. Interested individuals or an institution who wish to request access to the health claims data of the AOK, please contact the WIdO (webpage: http://www.wido.de/, mail: wido@wido.bv.aok.de).