Measuring quality of life in people with intellectual and multiple disabilities: validation of the San Martín scale

Abstract

Although there are numerous quality of life instruments in the, field of intellectual disability, most of them are addressed to those, people with the highest levels of functioning, while only a few are, suitable for people with the lowest levels (i.e., people with profound, and severe intellectual disabilities, or people with intellectual and, developmental disabilities and other significant medical conditions or, disabilities). This study provides reliability and validity evidence of, the San Martín Scale, a 95-item Likert scale questionnaire that is, completed by a third-party respondent. The validation sample was composed, of 1770 people from Spain with intellectual and developmental, disabilities that showed extensive or pervasive support needs (8.7% had, mild intellectual disability, 28.25% moderate, 41.6% severe, and 21.4%, profound). The age of the participants ranged between 16 and 77 years old, (M=7.78; SD=12.32). The results suggested that the eight quality of, life domains assessed on the scale are reliable (Cronbach's alpha ranging, from .821 to .933). Confirmatory Factor Analyses provided construct, validity evidences related to the internal structure of the San Martín, Scale, and indicated that the eight first-order factor solution provided, the best fit to the data over unidimensional and hierarchical solutions. Implications of these findings and guidelines for further research are, discussed.

Keywords: Developmental disabilities; Intellectual, disability; Measurement; Profound intellectual and multiple disabilities; Psychometric evaluation; Reliability; Validation.