Factor structure of the Hospital Anxiety and Depression Scale in coronary heart disease patients in three countries.

BACKGROUND Depression and anxiety in patients with coronary heart disease (CHD) is associated with a poorer prognosis. Therefore, the screening for psychological distress is strongly recommended in cardiac care and rehabilitation. The Hospital Anxiety and Depression Scale (HADS) is a widely used screening tool that has demonstrated good sensitivity and specificity for mental disorders. The factor structure of the HADS was investigated in CHD populations across three countries (Germany, Hong Kong, United Kingdom). METHODS In total, HADS data from 1793 patients with CHD were explored using confirmatory factor analysis to establish the underlying factor structure of the instrument. RESULTS Three-factor models were found to offer a superior fit to the data compared with two-factor (anxiety and depression) models in all countries. The anxiety items can be separated in a factor labelled autonomic anxiety and negative affectivity. CONCLUSIONS The HADS offers good possibilities to detect distressed patients with somatic illnesses, but the construct validity of the originally proposed two factors (depression, anxiety) remains unclear. In outcome studies, more precise scales should be used to reduce measurement errors based on the scales used.