| Summary: | How and why depression confers greater risk of impaired adaptation following coronary artery bypass graft (CABG) surgery is not well understood. This PhD aimed to address these issues by: developing and piloting a longitudinal study (the ARCS study) in order to track the recovery of patients undergoing CABG surgery; and conducting an extended version of the ARCS study on which to test the association between pre-operative depression and post-operative recovery and the underlying social-behavioural, cognitive and biological pathways. Outcomes were studied in the early and short term, namely three to five days (216 participants) and two months (154 participants) following surgery. The results indicated that greater pre-operative depression symptoms were predictive of poorer recovery, including longer in-hospital stays, greater emotional distress, physical symptoms and pain in the early term, and greater emotional distress, physical symptoms and pain and impaired health status in the short term, independent of demographic and disease severity factors (all p <0.05). Some associations were limited to subtypes of depression symptoms. Specifically, somatic/affective, but not total or cognitive/affective, depression symptoms were predictive of short-term outcomes. Mediators of the depression-recovery relationship were tested. Social support and behavioural factors were not shown to be mediators, but instead physical activity, body mass index and smoking status all had independent effects on recovery. Cognitive mediation was shown, with greater pre-operative negative illness perceptions mediating the relationship between pre-operative depression symptoms and post-operative anxiety and physical symptoms in the early term, and affective pain and physical symptoms in the short term. Biological mediation was not shown: although depression symptoms were related to neuroendocrine and inflammatory patterns suggestive of poorer physical functioning, these patterns did not consistently relate to recovery. Further work is needed to translate these findings into new ways to approach the measurement, diagnosis and treatment of depressed cardiac surgery patients.
|
|---|
