Positive affect and negative affect correlate differently with distress and health-related quality of life in patients with cardiac conditions: validation of the Danish Global Mood Scale.

OBJECTIVE The Global Mood Scale (GMS), assessing negative affect (NA) and positive affect (PA), is sensitive to tapping treatment-related changes in patients with cardiac conditions. We examined the psychometric properties of the Danish GMS and the influence of NA and PA on distress and health-related quality of life (HRQL). METHOD A mixed group of patients with cardiac conditions (n=502) completed the GMS, the Hospital Anxiety and Depression Scale, the Type D Scale, and the 36-item Short-Form Health Survey. RESULTS The two-factor model of the Danish GMS was confirmed, and the scale was shown to be valid, internally consistent (Cronbach's alpha NA/PA=.93/.85), and stable over 3 weeks (Pearson's r NA/PA=.82/.80). Unadjusted multiple linear regression analyses showed NA (beta=0.67, P<.001), PA (beta=-0.17, P=.001), and the interaction effect NA x PA (beta=-0.17, P=.015) to be associated with anxiety and depressive symptoms (NA:beta=0.99, P<.001; PA:beta=-0.12, P=.004; NA x PA:beta=-0.43, P<.001), as well as with physical HRQL (NA:beta=-0.37, P<.001; PA:beta=0.17, P=.001; NA x PA: beta=-0.27, P<.001) and mental HRQL (NA:beta=-0.72, P<.001; PA:beta=0.27, P=.004; NA x PA:beta=0.23, P<.001). When adjusting for demographic and clinical characteristics, only NA (beta=0.26, P=.003) was associated with anxiety, whereas NA (beta=0.75, P<.001) and NA x PA (beta=-0.34, P=.002) were associated with depressive symptoms. For physical HRQL, PA (beta=0.21, P=.03) and NA x PA (beta=-0.36, P=.005) remained significant, whereas NA (beta=-0.38, P<.001) and PA (beta=0.21, P=.002) remained significant for mental HRQL. CONCLUSION The Danish GMS is a psychometrically sound measure of affect in patients with cardiac conditions. Future studies should examine changes in both PA and NA and their impact on health outcomes.