Estimating sexual knowledge of people with mild intellectual disability through a valid and reliable assessment scale: The ISK-ID

Background Despite the relevance of assessing sexual knowledge in people with Intellectual Disability, there is a lack of appropriate assessment tools to measure this domain. The current study tests the psychometric properties of the new ‘Inventory of Sexual Knowledge of people with Intellectual Disability’ (ISK-ID). Method 345 individuals with mild intellectual disability completed the ISK-ID before and after the implementation of a sexual education program. Psychometric properties of the ISK-ID were analysed according to Multidimensional Item Response Theory (MIRT). Results Its underlying factorial structure, along with parameters derived from the MIRT (item discrimination, difficulty, and participant's ability), support the use of the ISK-ID as a measure of sexual knowledge. Moreover, the ISK-ID was able to detect changes in the level of sexual knowledge resulting from educational interventions (i.e., responsiveness). Conclusions The ISK-ID is an appropriate assessment tool to measure sexual knowledge in men and women with mild intellectual disability