Emotional distress and fatigue in coronary heart disease: the Global Mood Scale (GMS)

Abstract

Evidence indicates that emotional distress has a long-term impact on morbidity and mortality in patients with coronary heart disease (CHD), and that symptoms of depression, fatigue, and reduced energy may identify high-risk patients. This study was designed to: (1) devise a sound and practical measure of emotional distress in CHD patients; (2) examine the relationship between emotional distress and fatigue following CHD; and (3) examine changes in emotional distress as a function of cardiac rehabilitation. A sample of 478 men with CHD (mean age = 57.8 +/- 8.7 y) filled out questionnaires 3-6 weeks following a myocardial infarction (N = 110), bypass surgery (N = 302), or coronary angioplasty (N = 66). Statistical analyses of 56 Dutch mood terms were used to produce the 20-item Global Mood Scale (GMS) which measures negative affect (characterized by fatigue and malaise), as well as positive affect (characterized by energy and sociability), in patients with CHD. The GMS was found to be a reliable scale (alpha > 0.90; r > 0.55 over a 3-month period), and correlations with existing measures of emotional functioning and self-deception indicated its convergent and discriminant validity. Most importantly, fatigue was not related to cardiorespiratory fitness in a subset of 140 patients, but clearly was associated with negative affect. Consistent with the self-efficacy model, scores on the GMS mood scales improved significantly as a function of rehabilitation (P < 0.0001). Although symptoms of emotional distress are easily explained away by situational factors, previous research suggests that failure to recognize the clinical significance of these symptoms in CHD patients may result in the delay of much needed intervention. The current findings suggest that the GMS is a theoretically and psychometrically sound measure of emotional distress in CHD patients, and that this scale is sufficiently sensitive to assess change.