AbstractThe prevalence of intellectual disabilities is often quoted at 1 %. A meta-analysis of articles published between 1980 and 2009 confirmed this prevalence. Changes in diag-nostic practices, population characteristics, and exposure to known risk factors in recent years place this estimate in ques-tion and make it imperative to examine more recent studies of prevalence and incidence. Twenty relevant articles were ob-tained from five databases (PubMed, Embase, PsycInfo, Cochrane, and MEDLINE), published between 2010 and
2015. Most studies (n=17) only reported prevalence esti-mates, while two provided incidence estimates. Various meth-odologies were applied, with the majority of studies (n=16) using administrative data. Heterogeneity in study settings,
methodologies, age groups, and case definitions contributed to a range of prevalence estimates (0.05 to 1.55 %). Future research should include reproducible and consistent definitions of intellectual disabilities, provide age-specific es-timates, and monitor changes in prevalence over time. KeywordsPrevalence.Incidence .Intellectual disability. Developmental disability.
Meta-analysis.Review