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-R and 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% CI=36.1-61.2) per 1000 person-years; ICD-10: 45.8 (95% CI=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.