The impact of pre-operative depression on pain outcomes after major surgery: a systematic review and meta-analysis.

Symptoms of depression are common among patients before surgery. Depression may be associated with worse postoperative pain and other pain-related outcomes. This review aimed to characterise the impact of pre-operative depression on postoperative pain outcomes. We conducted a systematic review of observational studies that reported an association between pre-operative depression and pain outcomes after major surgery. Multilevel random effects meta-analyses were conducted to pool standardised mean differences and 95%CI for postoperative pain scores in patients with depression compared with those without depression, at different time intervals. A meta-analysis was performed for studies reporting change in pain scores from the pre-operative period to any time-point after surgery. Sixty studies (n = 501,962) were included in the overall review, of which 18 were eligible for meta-analysis. Pre-operative depression was associated with greater pain scores at < 72 h (standardised mean difference 0.97 (95%CI 0.37-1.56), p = 0.009, I2 = 41%; moderate certainty) and > 6 months (standardised mean difference 0.45 (95%CI 0.23-0.68), p < 0.001, I2 = 78%; low certainty) after surgery, but not at 3-6 months after surgery (standardised mean difference 0.54 (95%CI -0.06-1.15), p = 0.07, I2 = 83%; very low certainty). The change in pain scores from pre-operative baseline to 1-2 years after surgery was similar between patients with and without pre-operative depression (standardised mean difference 0.13 (95%CI -0.06-0.32), p = 0.15, I2 = 54%; very low certainty). Overall, pre-existing depression before surgery was associated with worse pain severity postoperatively. Our findings highlight the importance of incorporating psychological care into current postoperative pain management approaches in patients with depression.