Assessment of health-related quality of life in individuals with depressive symptoms: validity and responsiveness of the EQ-5D-3L and the SF-6D

Background The EQ-5D and the SF-6D are examples of commonly used generic preference-based instruments for assessing health-related quality of life (HRQoL). However, their suitability for mental disorders has been repeatedly questioned. Objective To assess the responsiveness and convergent validity of the EQ-5D-3L and SF-6D in patients with depressive symptoms. Methods The data analyzed were from cardiac patients with depressive symptoms and were collected as part of the SPIRR-CAD (Stepwise Psychotherapy Intervention for Reducing Risk in Coronary Artery Disease) trial. The EQ-5D-3L and SF-6D were compared with the HADS (Hospital Anxiety and Depression Scale) and PHQ-9 (Patient Health Questionnaire) as disease-specific instruments. Convergent validity was assessed using Spearman’s rank correlation. Effect sizes were calculated and ROC analysis was performed to determine responsiveness. Results Data from 566 patients were analysed. The SF-6D correlated considerably better with the disease-specific instruments (| r s |= 0.63–0.68) than the EQ-5D-3L (| r s |= 0.51–0.56). The internal responsiveness of the SF-6D was in the upper range of a small effect (ES: − 0.44 and − 0.47), while no effect could be determined for the EQ-5D-3L. Neither the SF-6D nor the EQ-5D-3L showed acceptable external responsiveness for classifying patients’ depressive symptoms as improved or not improved. The ability to detect patients whose condition has deteriorated was only acceptable for the EQ-5D-3L. Conclusion Overall, both the convergent validity and responsiveness of the SF-6D are better than those of the EQ-5D-3L in patients with depressive symptoms. The SF-6D appears, therefore, more recommendable for use in studies to evaluate interventions for this population.