Revisiting the dimensionality of the Hospital Anxiety and Depression Scale in an international sample of patients with ischaemic heart disease.
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Recently controversy has surrounded the dimensionality of the Hospital Anxiety and Depression Scale (HADS). We assessed the dimensionality of the HADS in a large international sample of patients with ischaemic heart disease (IHD) using confirmatory factor analysis (CFA). The analysis of an international sample enabled the current study to broaden knowledge gained from existing studies with small, regional samples.
Data from the HeartQoL study of patients with IHD (n=6241, 22 countries speaking 15 languages) were analyzed using CFA.
CFA indicated a hierarchical bifactor solution, with mostly strong item loadings on a general factor (explaining 73% of the variance), and weak to very weak loadings on orthogonal depression (16%) and anxiety (11%) subscales. The bifactor model fits the data significantly better than both the original bidimensional model and Dunbar's higher-order three-factor model.
These results, from a large international sample of patients with IHD, suggest that the HADS scale is dominated by a single general distress factor. Although the best CFA model fit was a hierarchical bifactor solution, the subscales had weak item loadings, providing little psychometric evidence of the ability of the HADS to differentiate anxiety and depressive symptoms. It is argued that clinicians and researchers working with patients with IHD should abandon the HADS and use alternative measures of depression and anxiety.