Three-dimensional structure of the Hospital Anxiety and Depression Scale in a large French primary care population suffering from major depression.

Few studies have been specifically carried out to characterize the dimensional structure of the Hospital Anxiety and Depression Scale (HADS) and those that have, have yielded contradictory results. We have examined the factor structure and sensitivity to change of the HADS in a large French outpatient primary care population treated with sertraline for major depression (DSM-IV criteria). Factor analysis of the HADS was performed in 2669 outpatients and in subsamples using a principal component procedure with Varimax rotation. Concurrent change sensitivity of the HADS was compared with that for the Hamilton Depression Rating Scale (HDRS) after at least 45 days of sertraline treatment. Three distinct factors emerged from the HADS factor analysis: a "depression" factor and two separate anxiety subscales: "psychic anxiety" and "psychomotor agitation" whose mean reductions in scores from baseline were significantly correlated (0.36-0.45) with the reduction of the HDRS baseline score. These new data provide support for the use of the HADS's three-dimensional structure to measure improvement of selected symptoms of anxiety during antidepressant therapy.