Applying generalizability theory methods to assess continuity and change on the Adolescent Quality of Life-Mental Health Scale (AQOL-MHS).

PURPOSE: The Adolescent Quality of Life-Mental Health Scale (AQOL-MHS) is designed to measure quality of life in clinical samples of Latino adolescents aged 12-18 years. Initial findings support its reliability, validity and conceptual model for use of its three domains (emotional regulation, self-concept and social context). Our current study tests the usefulness of the AQOL-MHS for tracking changes in HRQOL during the course of service use. METHODS: Three waves of data were collected from 59 participants who were recruited from mental health clinics, where waves were spaced 4 months apart. Participants were receiving services at baseline assessment and were tracked for follow-up appointments regardless of treatment status. We analyze conventional reliability statistics for individual differences (e.g., Cronbach's alpha and test-retest correlations), and to estimate the reliability of change, we carried out a variance decomposition analysis. RESULTS: The psychometric analyses from Chavez et al. (Qual Life Res 23(4):1327-1335, 2014) were replicated with comparable results. A generalizability theory (GT) analysis revealed that the AQOL-MHS domains can measure change reliably. The reliability estimates varied from .65 to .78. Although there was reliable change at the individual level, on the average the AQOL-MHS means improved only slightly over time. CONCLUSIONS: The reliability of change for all three scales in the AQOL-MHS was acceptable, but consistently lower than the Cronbach's alpha values for each wave. Future work will use this approach to adapt our current measure to provide a better reliability of within-person change and thus broaden its applicability for prospective use.