Early postoperative pain and 30-day complications following major abdominal surgery: a retrospective cohort study

Increasing evidence supports a positive relationship between the intensity of early postoperative pain, and the risk of 30-day postoperative complications. Higher pain levels may hamper recovery and contribute to immunosuppression after surgery. This leaves patients at risk of postoperative complications. One thousand patients who underwent major abdominal surgery (cytoreductive surgery and hyperthermic intraperitoneal chemotherapy, esophageal, liver, or pancreas surgery) at the Radboud university medical center were randomly selected from eligible patients between 2014 and 2020. Pain scores on day 1, the independent variable of interest, were extracted from the electronic patient files. Outcome measures were 30-day postoperative complications (infectious, non-infectious, total complications and classification according to Clavien-Dindo). Seven hundred ninety complications occurred in 572 patients within 30 days after surgery, of which 289 (36.7%) were of infectious origin, and 501 (63.4%) complications were non-infectious. The mean duration from the end of surgery to the occurrence of infectious complications was 6.5 days (SD 5.6) and 4.1 days (SD 4.7) for non-infectious complications (p<0.001). Logistic regression analysis revealed that pain scores on postoperative day 1 (POD1) were significantly positively associated with 30-day total complications after surgery (OR=1.132, 95% CI (1.076 to 1.190)), Clavien-Dindo classification (OR=1.131, 95% CI (1.071 to 1.193)), infectious complications (OR=1.126, 95% CI (1.059 to 1.196)), and non-infectious complications (OR=1.079, 95% CI (1.022 to 1.140)). After major abdominal surgery, higher postoperative pain scores on day 1 are associated with an increased risk of 30-day postoperative complications. Further studies should pursue whether optimization of perioperative analgesia can improve immune homeostasis, reduce complications after surgery and enhance postoperative recovery.