A comparison of Short Form 36 and Hospital Anxiety and Depression Scale based on patients 1 month after discharge from the intensive care unit

Introduction

Although the Hospital Anxiety and Depression Scale (HADS) and the health-related quality of life assessed by the Short Form 36 (SF-36) have been used concomitantly in several studies, extensive comparisons between HADS and the different components of SF-36 have previously been reported but not in ICU survivors. The aim of this study was to compare the scorings of anxiety and depression assessed by the HADS (HADA (Anxiety) and HADD (Depression)) with the scorings on the various domains of SF-36.

Methods

In a six-bed mixed (predominantly medical) ICU in a community hospital, 111 adult ICU survivors with a minimum stay of 72 hours were included. One month after ICU discharge or soon after hospital discharge they were sent the SF-36 and the HADS using regular mail. SF-36 tests eight domains. Four domains assess physical health, physical functioning (PF), role limitation due to physical problems (PR), bodily pain (BP) and general health perception (GH); while the other four assess psychological health, social functioning (SF), role limitation due to emotional problems (RE), energy and vitality (VT) and mental health (MH). The physical health summary score (PCS) reflects PF, PR, BP, and GH. The mental health summary scale (MCS) reflects VT, SF, RE, and MH. Pearson's correlation coefficients were calculated on item and scale levels to assess the associations between the HADS and the SF-36 scales.

Results

HADA and HADD were significantly associated with MCS but not with PCS. The absolute r value between MCS and HADA (0.72) was significantly higher than the comparable figure between HADD and MCS (0.68). HADA explained 1% of the variance of PCS and 52% of the variance of MCS. The comparable figures for HADD were 2% and 47%, respectively. Differences of correlation coefficients were further explored by evaluation of the associations between HADS and each of the eight SF-36 subscales. Only the association between HADA and PF was not statistically significant. Relatively high r values were observed between HADA (0.76) or HADD (0.65) and MH. The associations between HADA and MH exceeded significantly the analogue r values as to HADD.

Conclusions

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 assessment.