Objectives: Depression has been associated with increased cardiovascular morbidity and mortality. This study aimed to determine whether self-reported preoperative depressive symptoms were associated with worse long-term survival in patients undergoing cardiac surgery.

Methods: This population-based, observational cohort study included patients who had undergone cardiac surgery at Karolinska University Hospital between 2013 and 2016. Self-reported data about depressive symptoms were collected using the Patient Health Questionnaire (PHQ-9) and other patient data were collected from the institutional surgical database and medical charts. Depression was defined as a PHQ-9 score ≥10. Weighted flexible parametric survival models were used to estimate the association between self-reported preoperative depressive symptoms and all-cause mortality and to quantify absolute survival differences.

Results: Of the 1120 study patients, 162 (14.5%) had depressive symptoms before cardiac surgery. During a mean follow-up of 7.2 years (maximum, 9.2 years), there were 36 deaths in 1129 person-years (PYs) in the depressed group, compared to 160 deaths in 6889 PYs in the non-depressed group. In the adjusted analysis, self-reported depressive symptoms were associated with worse long-term survival (hazard ratio 1.66; 95% confidence interval 1.09-2.54) compared with no reported depressive symptoms. The absolute survival differences (% and 95% confidence interval) between the non-depressed and the depressed patients were -1.9 (-3.9 to 0.19), -5.7 (-11 to -0.01) and -9.7 (-19 to -0.4) after 1, 5 and 8 years, respectively.

Conclusions: Self-reported preoperative depressive symptoms were associated with worse long-term survival following cardiac surgery and should be regarded as important as other classical risk factors.