Association of postoperative complications with persistent post-surgical pain: a multicentre prospective cohort study

Persistent post-surgical pain is an important and under-recognised problem that is difficult to treat. Postoperative complications have been identified as possible risk factors for persistent post-surgical pain. We conducted a secondary analysis of the Measurement of Exercise Tolerance before Surgery (METS) cohort study to characterise the association of major postoperative complications with post-surgical pain at 30 days and 1 yr after major surgery. The analysis included 1313 participants (≥40 yr old) who had inpatient noncardiac surgery and survived for 1 yr. The co-primary outcomes were 30-day post-surgical pain and 1-yr post-surgical pain. Post-surgical pain was defined as pain or discomfort that was of moderate or severe intensity (EuroQoL-5D [EQ-5D] instrument) and unimproved compared with preoperative pain or discomfort. The principal exposure was major in-hospital complications (moderate or severe by modified Clavien–Dindo criteria). Multivariable logistic regression modelling was used to characterise the adjusted association of major complications with outcomes. Of the cohort, 12% ( n =163) experienced major complications, 51% ( n =674) reported 30-day post-surgical pain, and 42% ( n =545) reported 1-yr post-surgical pain. Major complications were associated with 30-day post-surgical pain (adjusted odds ratio [aOR]=1.54; 95% confidence interval [CI], 1.05–2.23) and possibly 1-yr post-surgical pain (aOR=1.42; 95% CI, 0.98–2.06). When analyses were repeated after multiple imputation of missing covariate and outcome data, complications were associated with both 30-day and 1-yr post-surgical pain. Patients who developed major complications were more likely to report pain at 30 days and possibly 1 yr after surgery. Research is necessary to validate these findings and delineate underlying mechanisms.