Psychological distress mediates the effects of socio-demographic and clinical characteristics on the physical health component of health-related quality of life in patients with coronary heart disease

Background:This study aimed to examine the mediating role of psychological distress in the relationship between the physical health component of health-related quality of life (HRQoL) of coronary heart disease patients and their socio-demographic and clinical characteristics. Methods:This was a cross-sectional study conducted from March 2009 to July 2010 with a total of 420 participants recruited from two hospital-based phase II cardiac rehabilitation centres. Participants' socio-demographic variables, self-reported medical history data, level of psychological distress, perceived social support, and HRQoL were collected by means of a structured questionnaire. Body weight and height, blood pressure and clinical data including fasting blood glucose, triglycerides, and low- and high-density lipoprotein cholesterol were also collected. Exploratory univariate analyses and multivariable regressions were conducted to identify socio-demographic and clinical determinants of the physical health component of HRQoL. Path analyses were then performed to examine the mediating role of psychological distress in the relationship between the physical health component of HRQoL and the determinants. Results:Path analysis revealed that age, sex, perceived social support, history of angina, and dyslipidaemia had both direct effect and indirect effect through psychological distress on the physical health component of HRQoL. Obesity and impaired left ventricular function only affected the physical health component of HRQoL directly, whereas household income only affected it indirectly, through psychological distress. Conclusion:Psychological distress mediates the effects of some socio-demographic and clinical variables of CHD patients on the physical health component of HRQoL. Our findings have important implications for rehabilitation care for people with CHD in order to enhance their HRQoL.