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

Summary 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 6 months (standardised mean difference 0.45 (95%CI 0.23–0.68), p < 0.001, I 2 = 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, I 2 = 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, I 2 = 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.