Prevalence of intellectual disability: a comprehensive study based on national registers


Hannu Westerinen, Höylätie 5A, 01650 Vantaa, Finland (e-mail:


Background  Based on standard social benefit registers, the prevalence of intellectual disability (ID) in Finland is estimated to be 0.6%, while epidemiological surveys yield 1.1%. Combining several registers, our aim was to find a more reliable estimate of the prevalence of ID, especially among children and adolescents. This is important when special or inclusive general services are planned to meet the various needs of people with ID.

Method  A survey based on eight national health and social benefit registers.

Results  Combining different registers yielded a mean ID prevalence of 0.70% (95% CI 0.69–0.70%), with marked differences according to sex and age group (range 0.38–0.96%). Capture–recapture analysis gave higher prevalence estimates (range 0.57–1.08%).

Conclusions  When several health and social benefit registers are surveyed, the estimated prevalence of ID increases, approaching that obtained in epidemiological surveys.