[Epidemiologic study of the estimated number of older patients with Down's syndrome in 1990-2025]

Since a population-based registry of the mentally retarded is lacking in The Netherlands, data concerning incidence and life expectancy patients with Down's syndrome (DS) are not available. Based on birth statistics, in combination with risk factors for DS in relation to maternal age on the one hand and on studies on life expectancy in DS from Denmark, British Columbia and Western Australia on the other, the numbers of these patients older than 40 years were estimated for The Netherlands for the period 1990-2025. After a considerable increase of the number of institutionalized DS patients of 40 years and older between 1958 and 1985, the present estimates indicate a further rise. It is expected that the level of aged DS patients will be highest between 2005 and 2020, and will increase at least to numbers 50% above those expected for 1990. These findings have to have an impact on the capacity planning for institutes for the mentally retarded.