Background: The aim of this study was to compare the scorings of anxiety and depression assessed by the Hospital Anxiety and Depression Scale (HADS-A [Anxiety] and HADS-D [Depression]) with the scorings on the eight subscales of Short Form 36 (SF-36) and the Physical (PCS) and Mental Component Summary (MCS) assessed by the same patients.
Method: In a cross-sectional study 736 long-term survivors after treatment for testicular cancer (TC) completed HADS and SF-36. Pearson's correlation coefficients were calculated on item and scale level to assess the associations between the HADS and the SF-36 scales and, in particular, between HADS and PCS and MCS, respectively. Independent predictors for PCS and MCS were identified by linear regression analysis.
Results: HADS-A and HADS-D were significantly associated with the SF-36 summary scales. HADS-A explained 5% of the variance of PCS and 49% of the variance of MCS. The comparable figures for HADS-D were 10% and 45%, respectively. In the multivariate analysis the HADS-D scoring independently predicted the level of PCS together with the patients' educational level, long-lasting working disability and age (variance: 30%). Both HADS-D and HADS-A remained independent parameters for MCS (variance: 58%) together with the patient's civil status. HADS-D item D4 ("slowed down") was similarly associated with both PCS and MCS.
Conclusion: In univariate analyses HADS-D and HADS-A were statistically associated with PCS and MCS. The highest r values were observed for the associations between HADS and MCS, in particular between HADS-A and MCS. In the multivariate analyses HADS-D, but not HADS-A, contributed to PCS, whereas both HADS-A and HADS-D were associated with MCS. This pattern of different predictions of the summary scales of SF-36 supports a clinical practice that anxiety and depression should be assessed separately. Additional use of a self-rating instrument for depression and anxiety, such as HADS, is recommended when SF-36 is used for quality of life (QL) assessment.