Incidence of dementia according to DSM-III-R and ICD-10 - Results of the Leipzig Longitudinal Study of the Aged (LEILA75+) Part 2

Background The impact of different case definitions on incidence rates remains unclear. Aims To compare incidence rates of dementia according to DSM-III-Rand ICD-10. Method A two-wave community study was conducted (n= 1692, age 75+ years follow-up period 1.6 years). Cognitive function was assessed by the Structured Interview for Diagnosis of Dementia of Alzheimer Type, Multiinfarct Dementia and Dementia of other Aetiology according to ICD-10 and DSM-III-R (SIDAM). Results The annual incidence rate for dementia by applying different case definitions was found to be quite similar (DSM-III-R: 47.4 (95% Cl =36.1-61.2) per 1000 person-years; ICD-10: 45.8 (95% Cl =35.0-59.0) per 1000 person-years). Age-specific incidence rates increase steeply with age. Conclusions The impact of different case definitions on incidence rates of dementia appears limited if case definitions and case-finding procedures at baseline and follow-up are applied consistently. Declaration of interest Supported by Interdisziplinaeres Zentrum fur Klinische Forschung (IZKF), University of Leipzig