Psychological mediators related to clinical outcome in cognitive behavioural therapy for coronary heart disease : A sub-analysis from the SUPRIM trial

Background:The Secondary Prevention in Uppsala Primary Healthcare Project (SUPRIM) was a randomized controlledtrial of a group-based cognitive behavioural therapy stress management programme for patients with coronary heartdisease. The project was successful in reducing the risk of fatal or non-fatal first recurrent cardiovascular events. The aimof this study was to analyse the effect of cognitive behavioural therapy on self-rated stress, somatic anxiety, vitalexhaustion and depression and to study the associations of these factors with the reduction in cardiovascular events. Methods:A total of 362 patients were randomly assigned to intervention or usual care groups. The psychologicaloutcomes were assessed five times during 24 months and analysed using linear mixed models. The mediating roles of theoutcomes were analysed using joint modelling of the longitudinal and time to event data. Results:The intervention had a positive effect on somatic anxiety (p<0.05), reflecting a beneficial development overtime compared with the controls. Stress, vital exhaustion and depression did not differ between the groups over time.Mediator analysis suggested that somatic anxiety may have mediated the effect of treatment on cardiovascular events. Conclusions:The intervention had a small positive effect on somatic anxiety, but did not affect stress, vital exhaustionor depression in patients with coronary heart disease. Somatic anxiety was associated with an increased risk of cardio-vascular events and might act as a partial mediator in the treatment effect on cardiovascular events. However, themechanisms between the intervention and the protective cardiovascular outcome remain to be identified.