Depression 12-months after coronary artery bypass graft is predicted by cortisol slope over the day.

Alterations in the diurnal profile of cortisol have been associated with depressed mood in patients with coronary heart disease. The relationship between cortisol output and depressed mood has not been investigated prospectively in coronary artery bypass graft (CABG) patients before. We aimed to study the relationship between cortisol measured pre- and post-operatively and depression symptoms measured 12 months after CABG surgery. We analysed data from 171 patients awaiting first-time, elective CABG surgery from the pre-assessment clinic at St. George's Hospital, London. The Beck Depression Inventory (BDI) was used to assess depression symptoms and saliva samples were collected to measure diurnal cortisol. Baseline assessments of depression and cortisol were obtained an average 29days before surgery, short-term follow-up of cortisol occurred 60days after surgery and long-term follow-up of depression was assessed 378days after surgery. Baseline cortisol slope was not associated with depression at 12-month follow-up. However, a steeper cortisol slope measured 60days after surgery predicted reduced odds of depression (BDI≥10) 12 months after surgery (odds ratio 0.661, 95% confidence interval 0.437-0.998, p=0.049) after controlling for covariates. These findings suggest interventions aimed at improving adaptation in the early recovery period may have long-term benefits in this patient group.