Spatial patterns of dementia prevalence and its vascular risk factors in Germany

Gabriele Doblhammer-Reiter, University of Rostock
Thomas Fritze, German Center for Neurodegenerative Diseases (DZNE)
Stefan Teipel, University of Rostock

This is the first study that explored spatial patterns in the prevalence of dementia in Germany. Results about sub-national differences in other countries have been inconclusive. We used health claims data from the largest public health insurer in Germany for ages 65 and above in the year 2007 consisting of 1,312,594 persons. Dementia diagnosis was defined according to ICD-10 codes G30, G31.0, G31.82, G23.1, F00, F01, F02, F03, and F05.1. We distinguished 95 regions according to the 2-digit postal code of the place of residence. Using meta-regression models we found significant geographical differences in age standardized prevalence rates of dementia. Dementia prevalence was higher in East than in West Germany. In East Germany the prevalence declined from the north to the south, in West Germany the prevalence was low in the north and particularly high in the north and eastern regions of Bavaria. The regional prevalences of dementia were significantly correlated with the regional prevalences of the three major vascular risk factors hypertension, hypercholesteremia, and diabetes. Together the regional variation in the three risk factors explained about 50% of the regional variation in dementia prevalence. The relationship between vascular risk factors and dementia has been repeatedly demonstrated on the individual level. Our results confirm that this relationship also exists on a regional level. We conclude by discussing possible limitations of the data and how they might bias the results.