Calibrating well-being, quality of life and common mental disorder items: psychometric epidemiology in public mental health research.

Abstract

BackgroundThe assessment of ‘general health and well-being’ in public mental health research stimulates debates around relative merits of questionnaire instruments and their items. Little evidence regarding alignment or differential advantages of instruments or items has appeared to date.AimsPopulation-based psychometric study of items employed in public mental health narratives.MethodMultidimensional item response theory was applied to General Health Questionnaire (GHQ-12), Warwick-Edinburgh Mental Well-being Scale (WEMWBS) and EQ-5D items (Health Survey for England, 2010–2012; n = 19 290).ResultsA bifactor model provided the best account of the data and showed that the GHQ-12 and WEMWBS items assess mainly the same construct. Only one item of the EQ-5D showed relevant overlap with this dimension (anxiety/depression). Findings were corroborated by comparisons with alternative models and cross-validation analyses.ConclusionsThe consequences of this lack of differentiation (GHQ-12 v. WEMWBS) for mental health and well-being narratives deserves discussion to enrich debates on priorities in public mental health and its assessment.