Complications and pain after surgery: a tertiary exploratory analysis of prospectively collected patient data

Chronic postsurgical pain (CPSP) presents a significant healthcare concern that warrants prevention efforts. However, the precise mechanisms leading to its development remain unclear. The objective of this study is to investigate the relationship between postoperative complications within the first 30 days and pain intensity experienced three months after surgery. In this tertiary exploratory analysis of our prospective observational cohort study we included 699 patients, who underwent planned surgery. The primary exposure variable was the occurrence of postoperative minor or major medical complications within one month after surgery. The primary outcome assessed was movement-evoked pain intensity at three months after surgery. Multivariable logistic regression analyses and sensitivity analyses were employed to determine the adjusted association between postoperative medical complications and movement-evoked pain at three months after surgery. Within the cohort, 34.8% ( n = 243) experienced at least one complication, and 13.9% ( n = 97) reported movement-evoked pain three months after surgery. In the primary analysis, postoperative complications were associated with increased odds of pain at three months (OR 2.12, 95% CI 1.05–4.29). However, sensitivity analyses addressing exposure definition and model specification substantially attenuated this association. Excluding pain-related complications from the exposure definition and alternative modelling strategies demonstrated that the primary association was not robust. The association between postoperative complications and pain at three months was highly sensitive to exposure definition and covariate adjustment. Further research is needed to clarify the role of specific postoperative complications in the development of persistent postoperative pain.