Monitoring the prevalence of severe intellectual disability in children across Europe: feasibility of a common database.

AIM: Our aim was to study the feasibility of creating a framework for monitoring and undertaking collaborative research on intellectual disability at the European level, based on existing databases of children with such disability.

METHOD: The characteristics of five existing European intellectual disability databases from four countries (Iceland, Latvia, Ireland, and two in France), were discussed on the basis of ideal criteria set by a working group on childhood intellectual disability as part of the Surveillance of Cerebral Palsy in Europe Network (SCPE-NET). Mean prevalence values for severe intellectual disability for the birth years 1990 till 2002 were compared across databases.

RESULTS: Methods of case recruitment and diagnosis differed across databases, but classification of intellectual disability and completeness were similar. Severe intellectual disability (IQ<50) prevalence estimates were significantly (p<0.001) different across databases (south-east France: 3.3 out of 1000; south-west France: 3.0 out of 1000; Latvia: 3.9 out of 1000; Ireland: 5.0 out of 1000; and Iceland 5.1 out of 1000).

INTERPRETATION: In spite of differences in diagnosis and case inclusion across databases, the construction of a common database for severe intellectual disability was deemed feasible through harmonization of certain criteria, such as age, and through restriction to those with severe intellectual disability.