The assessment of the quality of life of adults with intellectual disability: the use of self-report and report of others assessment strategies.

Assessment strategies that reliably and validly assess the indicators of quality of life (QOL) of individuals with intellectual disability (ID) are necessary for planning interventions and evaluating outcomes. In the present study, inter-rater reliability and concordance of the two assessment strategies report of others and self-report were evaluated in a group of 176 Italian adults with ID using the Personal Outcomes Scale, which employs the same QOL indicators in the self-report and report of others versions. Report of others resulted a reliable assessment strategy. Clients' point of view was compared with both the estimation of their point of view and third-party-point-of-view obtained by two independent caregivers for each client. Results indicated that both self-report and report of others assessment strategies are necessary and that estimation of the client's point of view may be a valid and reliable substitute of self-report when clients are not able to answer.