Postoperative acute pain trajectory and chronic postsurgical pain after abdominal surgery: a prospective cohort study and mediation analysis

BACKGROUND: This study aimed to investigate the trajectories of acute postoperative pain intensity during the initial 5 days after abdominal surgery, and to analyze their association with the risk of developing chronic postsurgical pain (CPSP). METHODS: We enrolled patients with elective abdominal surgery with pain measurements taken across postoperative days 1 through 5. Since postoperative pain is often unavoidable and its initial intensity is closely related to the invasiveness of the surgery, focusing on the overall pain trajectory may be more meaningful than evaluating pain at a single time point. Therefore, the primary outcome of this study was to identify distinct pain trajectories. Secondary outcome was the incidence of CPSP between differences pain trajectories. Lastly, mediation analyses were performed to explore the mediating role of the quality of recovery and subacute pain on the studied associations. RESULTS: The final analysis encompassed 1170 patients (36.75% female) with a median age of 55 years. Two distinct clusters were identified: with movement (high: 533 [45.56%]; low: 637 [54.44%]) and at rest (high: 363 [31.03%]; low: 807 [68.97%]). Patients in the high pain trajectory group (during movement [odds ratio [OR] 2.04, 95% CI 1.56-2.68] or at rest [OR 1.90, 95% CI 1.44-2.53]) exhibited nearly doubled risk of CPSP. Moreover, these patients exhibited a significantly poorer recovery quality. Mediation analyses revealed that the poor recovery quality at postoperative 5 days (17.62%-18.57%) and higher subacute pain at postoperative 1 month (29.46%-32.75%) were significant mediators in the association between adverse postoperative acute pain trajectory patterns and CPSP. CONCLUSION: This study highlights the clinical significance of postoperative pain trajectory profiles in predicting the risk of CPSP, emphasizing postoperative acute pain trajectory as a critical indicator and subacute pain as a significant mediator. The findings underscore the potential for tailored pain management strategies targeting acute pain trajectories to reduce such risk.