Enhancing the Validity of a Quality of Life Measure for Autistic People
Objectives: (1) To develop additional items which address important quality of life issues for autistic adults. (2) To explore the validity of the WHOQoL-BREF (26 items), WHO Disabilities module (WHOQoL-DIS, 13 items), and additional items with a sample of autistic adults.
Methods: Four focus groups of autistic adults were held to discuss the WHOQoL-BREF and WHOQoL-DIS (subscales are Autonomy, Inclusion and Discrimination). Eleven proposed items were developed from themes derived from transcripts from the recorded discussions. Fifteen cognitive interviews were carried out with autistic adults to assess the face and content validity of these items. A Delphi survey (N=374) was conducted over two rounds to refine the items and establish their importance and clarity. From this process, nine items (hereafter ASQoL) were carried forward for further testing.
309 participants (mean age=43.0 years, SD=13.8) took part in a validation study recruited via the Adult Autism Spectrum Cohort-UK (ASC-UK). Participants completed the WHOQoL-BREF, the WHOQoL-DIS, the ASQoL items, the Hospital Anxiety and Depression Scale (HADS), the Craig Hospital Inventory of Environmental Factors short form (CHIEF-SF), the Comprehensive Quality of Life Scale (COMQOL), and the Interpersonal Support Evaluation List-12 (ISEL-12). Measures were completed on paper and returned via post, or electronically via Qualtrics.
Results: Construct validity: Exploratory factor analysis (EFA) suggested a four factor model and confirmatory factor analysis showed acceptable fit overall (CFI=0.83, p<.001). Criterion validity: The COMQOL satisfaction subscale was significantly correlated with all WHOQoL-BREF domains (rs 0.59-0.79, all p<.001). Convergent/divergent validity: The WHOQoL-BREF domain scores were significantly correlated with all measures but showed stronger associations with hypothesised subscales (e.g. CHIEF-SF scores correlated significantly more strongly with the Environmental domain than the Psychological domain; z=5.63, p<0.001; ISEL-12 scores correlated significantly more strongly with the Social domain than the Physical domain; z=3.90, p<0.001). Discriminant validity: QoL scores for all subscales were significantly lower with increased depression and anxiety (HADS). Reliability: Overall internal consistency was excellent (α=0.93) and subscale consistency was acceptable to good (αs=0.68-0.87).
Conclusions: The findings on validity of the WHOQoL-BREF supports its use with autistic adults and strengthens conclusions from previous research. This is the first study to use the WHOQoL-DIS with autistic people, and alongside the proposed ASQoL items, makes a unique contribution to further representing, measuring and understanding their QoL needs.