Relationship Between Postoperative Pain and Overall 30-Day Complications in a Broad Surgical Population: An Observational Study.

Objective: The aim of this study was to establish the relationship between postoperative pain and 30-day postoperative complications.

Background: Only scarce data are available on the association between postoperative pain and a broad range of postoperative complications in a large heterogeneous surgical population.

Methods: Having postoperative pain was assessed in 2 ways: the movement-evoked pain score on the Numerical Rating Scale (NRS-MEP) and the patients' opinion whether the pain was acceptable or not. Outcome was the presence of a complication within 30 days after surgery. We used binary logistic regression for the total population and homogeneous subgroups to control for case complexity. Results for homogeneous subgroups were summarized in a meta-analysis using inverse variance weighting.

Results: In 1014 patients, 55% experienced moderate-to-severe pain on the first postoperative day. The overall complication rate was 34%. The proportion of patients experiencing postoperative complications increased from 0.25 [95% confidence interval (CI) = 0.21-0.31] for NRS-MEP = 0 to 0.45 (95% CI = 0.36-0.55) for NRS-MEP = 10. Patients who found their pain unacceptable had more complications (adjusted odds ratio = 2.17 (95% CI = 1.51-3.10; P < 0.001)). Summary effect sizes obtained with homogeneous groups were similar to those obtained from the total population who underwent very different types of surgery.

Conclusions: Higher actual postoperative pain scores and unacceptable pain, even on the first postoperative day, are associated with more postoperative complications. Our findings provide important support for the centrality of personalized analgesia in modern perioperative care.