OBJECTIVES : Broader life impacts of mental health conditions are often not captured in commonly used health-related quality of life (HRQoL) measures. The multi-dimensional OxCAP-MH well-being questionnaire was developed in the UK based on Sen’s capability approach to overcome these limitations. This study aimed to test the OxCAP-MH’s construct profile, psychometric validity and feasibility of implementing it in routine evaluation of mental health services in Austria.

METHODS : 159 Austrian patients receiving regular care in social-psychiatric services completed relevant questionnaires at baseline and 6-month follow-up. Reliability was assessed using Cronbach’s alpha, item-total correlations, and by investigating floor and ceiling effects. Test-retest analysis was estimated via repeated testing using ICC. Construct validity was tested by comparing the OxCAP-MH with other patient-reported measures (EQ-5D-5L/VAS, BSI-18, WHOQOL-BREF) and relevant observer rated instruments (Mini-ICF, GAF). Standardised response mean (SRM) was used to assess the responsiveness to changes over time. Factor analysis was conducted.

RESULTS : Good internal consistency (0.85), item-total correlations (0.29-0.61) and one-month test-retest analysis (ICC 0.80) proved reliability. No floor/ceiling effects were observed. Construct validity of the German OxCAP-MH and its ability to measure a broader concept of wellbeing in the mentally ill population was confirmed by strong correlations with generic HRQoL measures (EQ-5D-5L:0.66, EQ-5D VAS:0.58), relevant WHO-BREF dimensions (0.50 to 0.75), the BSI-18 (-0.67) and factor analysis. OxCAP-MH could distinguish between patients with different levels of QoL with the mean score of 48 and 74 for ‘very poor’ and ‘very good’ QoL. In terms of responsiveness, the instrument was able to detect patients who improved in their overall scores in the anchor instruments with SRMs ranging from 0.62 to 0.90.

CONCLUSIONS : The study confirmed good psychometric properties of the OxCAP-MH and its ability to measure patients’ broader wellbeing beyond HRQoL. The instrument also proved suitable for the routine evaluation of mental health services.