Abstract
BackgroundHealth utility assessments are important for economic evaluations but few instruments have been validated in homeless people with mental illness. We examined the convergent validity of the EuroQol-5 Dimension 3-level questionnaire (EQ-5D-3L) as a measure of quality of life in homeless adults with mental illness.MethodsData were from Toronto participants in At Home/Chez Soi, a 24-month randomized controlled trial of Housing First (immediate access to scattered site housing and mental health support services) compared to treatment as usual for homeless adults with a mental disorder (n = 575). Participants completed the EQ-5D-3L at 6 month intervals. We tested convergent validity, hypothesizing strong correlation (r > 0.6) with the Lehman Quality of Life Interview 20 (QOLI-20) index and moderate correlations (r > 0.3) with the Colorado Symptom Index (CSI), Recovery Assessment Scale (RAS), and number of comorbidities. We also examined correlations between EQ-5D-3L scores and the QOLI-20 over time using a linear mixed-effects model.ResultsThe EQ-5D-3L was not strongly correlated with the QOLI-20 (r ranged from 0.31–0.52 at various time points). The EQ-5D-3L was moderately correlated with the CSI, RAS, and number of comorbidities. The Snijders/Bosker r2 for longitudinal validity between the EQ-5D-3L and QOLI-20 within subjects over time was 0.2094 (square-root r = 0.4576).ConclusionsThe EQ-5D-3L did not demonstrate strong convergent validity in homeless people with mental illness but was moderately correlated with several instruments. Further research is warranted to determine the optimal method for measuring health utilities in this population.Trial registrationInternational Standard Randomised Control Trial Registry ISRCTN42520374 assigned on August 18, 2009.
Highlights
Health utility assessments are important for economic evaluations but few instruments have been validated in homeless people with mental illness
A recent comprehensive report on the use of generic preference-based measures of health in mental health populations concluded that the EQ-5D and 36-Item Short Form Survey (SF-36) achieve an adequate level of psychometric performance in patients with depression and, to some extent, in patients with anxiety and personality disorder; results were mixed in patients with serious mental illness such as schizophrenia and bipolar disorder and the report concluded that further validation studies were needed [10]
A Swedish study demonstrated lower EQ-5D-3L scores among homeless adults compared to population norms, with significantly lower scores among those sleeping “rough” and those reporting symptoms of mental illness [13]
Summary
Health utility assessments are important for economic evaluations but few instruments have been validated in homeless people with mental illness. Indirect utilities are preferred by some economists who view community ratings as the most appropriate approach to capture preferences for societallevel decision making [5] They may require less cognitive effort [6] and cause less distress [7] than direct methods, so may be more acceptable to participants, those with mental illness. The EuroQol-5 Dimension 3-level questionnaire (EQ5D-3L) is a popular indirect utility instrument [8] It has been recommended as the preferred method for measuring health-related quality of life by the UK’s National Institute for Health and Care Excellence (NICE), except in patient populations for which it performs poorly on tests of construct validity and responsiveness [9]. Neither study examined its convergent validity with other measures of quality of life and health
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