Psychological assessment
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Psychological assessment · Jun 2014
Multicenter StudyBifactor analysis and construct validity of the HADS: a cross-sectional and longitudinal study in fibromyalgia patients.
The dimensionality of the Hospital Anxiety and Depression Scale (HADS) is a current source of controversy among experts. The present study integrates a solid theoretical framework (Clark & Watson's, 1991, tripartite theory) and a fine-grained methodological approach (structural equation modeling; SEM) to examine the dimensionality and construct validity of the HADS in fibromyalgia (FM) patients. Using the HADS data of 269 Spanish patients with FM, we estimated the cross-sectional and, for the first time, longitudinal fit (autoregressive model) of 2 competing models (oblique 2-factor vs. bifactor) via confirmatory factor analysis. ⋯ Only the general factor of psychological distress showed adequate reliability. In conclusion, the HADS shows a clear bifactor structure among FM patients. Our results indicate that it is not recommendable to compute anxiety and depression scores separately because anxiety variance is tapped primarily by the broader construct of psychological distress, and both specific dimensions show low reliability.