Psychosocial factors and prognosis in coronary heart disease

Abstract

Aim: This thesis aims to contribute to the better understanding of the role of psychosocial factors in coronary heart disease (CHD) by analysing (1) the relationship of income, anger expression and work stress with prognosis after a cardiac event, (2) potential explanations for these associations and (3) whether a combined intervention consisting of a psychosocial rehabilitation and medical treatment from a cardiologist affects psychosocial risk factors and prognosis in women CHD patients.

Methods: Data from the Healthier Female Heart (HFH) study, a randomized controlled trial enrolling consecutively 247 women cardiac patients aged 75 years (papers I, II, IV) and data of 676 non-fatal acute myocardial infarction (AMI) cases from the Stockholm Heart Epidemiology Program (SHEEP) (paper III) were analysed. Patients from the HFH study were assigned either to an intervention group obtaining a 1-year psychosocial rehabilitation based on cognitivebehavioural therapy principles (20 x 2-hour sessions) and medical care by a cardiologist whom they met at least 3 times (n = 119), or to the control group with usual health care (n = 128). Demographic, socioeconomic, psychosocial, lifestyle-related, clinical and biological characteristics were obtained by means of questionnaires or clinical examination. In the HFH study, assessments were carried out at baseline (6-8 weeks after hospitalization and randomization), after 10 weeks, after 1 year (end of intervention) and at 1-2 years after intervention. SHEEP patients completed questionnaires soon after recovery from the AMI and underwent a standardised clinical examination 3 months later. Patients were followed for non-fatal AMI, cardiac/cardiovascular and total mortality for an average time of 6.5 years in the HFH study and of 8.5 years in the SHEEP study. Cox regression and mixed models were used to analyse prospective and longitudinal data, respectively.

Results: During the follow-up of the HFH study a total of 31 patients deceased, 17 of cardiac causes and 41 had the combined outcome of cardiac death and non-fatal AMI. The corresponding figures in the SHEEP study were 96 for total death, 52 for cardiac mortality and 155 for the combination of cardiac death and non-fatal AMI. In paper I, patients with medium and high income had a lower risk for recurrent events relative to those with low income; adjustment for smoking, depression and anger symptoms somewhat attenuated the relationship (paper I). The tendency to suppress angry feelings increased the risk for the combined endpoint of cardiovascular death and recurrent AMI and for all-cause mortality, whereas the outward expression of anger was associated with a higher risk for the combination of cardiovascular death and new AMI. Among the potential biological mediators inflammatory markers somewhat attenuated the relationship (paper II). High job strain was associated with an increased risk of cardiac and total mortality and of the combination of cardiac death and non-fatal AMI relative to low job strain. This relationship could not be explained by lifestyle, blood lipids, glucose, inflammatory and coagulation factors (paper III). After 6.5 years all-cause and cardiac mortality was lower in the intervention than in the control group, the hazard ratios and the 95% confidence intervals being 0.34 (0.15-0.76) and 0.41 (0.14-1.16), respectively. Differences in drug therapy prescribed by cardiologists and general practitioners partly explained the observed beneficial effect of the intervention. Moreover, favourable changes in some psychosocial variables might have also contributed to the explanation of the lower mortality in the intervention group (paper IV).

Conclusions: Our results suggest that low income, the suppression and the outward expression of anger, and job strain are associated with poor prognosis after a cardiac event. The combined intervention consisting of a psychosocial rehabilitation and medical therapy by a cardiologist reduced the risk of all-cause and cardiac specific mortality during a 6.5-year follow-up compared to usual care from the health care system. These findings have potentially substantial implications for secondary prevention of CHD.