Regional Pattern of Dementia and Prevalence of Hearing Impairment in Germany

Objectives: To determine the association between hearing impairment and dementia.

Design: Cross-sectional study.

Setting: Claims data of the Allgemeine Ortskrankenkasse, the largest public health insurance company in Germany.

Participants: Age-stratified sample of all insured persons aged 65 and above in the first quarter of 2007 (N = 1,338,462).

Measurements: Metaregression analysis on the association between regional prevalence of dementia and hearing impairment controlled for major vascular risk factors, including hypertension, hypercholesterolemia, diabetes mellitus, and cerebrovascular disease. Dementia and hearing impairment diagnoses were defined according to International Classification of Diseases, Tenth Revision, codes. Ninety-five regions were distinguished according to the two-digit postal code of the place of residence.

Results: A significant association was found between regional prevalences of dementia and hearing impairment that was preserved when controlling for major vascular risk factors (P = .003). Regional dementia prevalence increased by approximately 0.23% when the prevalence of hearing impairment increased by 1 standard deviation.

Conclusion: The relationship between hearing impairment and dementia has been repeatedly demonstrated on the individual level. The results of the current study confirm that this relationship also exists on a regional level. These findings underscore the potential role of hearing impairment as a risk factor for dementia that will be relevant for the management of elderly patients in general practice.