Effect of intraoperative infiltration with local anesthesia on the development of chronic pain after inguinal hernia repair: A randomized, triple-blinded, placebo-controlled trial

Background. Chronic pain is a common complication after inguinal hernia repair. The objective of this randomized trial was to assess the effect of intraoperative infiltration with local anesthetic versus placebo on the development of chronic pain after inguinal hernia repair Methods. Patients with single- or double-sided inguinal hernia were enrolled in a randomized, controlled, triple-blinded trial with a sequential adaptive design. Hernias were randomized to 1 of 2 treatment groups. The intervention group received a local infiltration of 20 mL bupivacaine 0.25% and the placebo group 20 mL saline 0.9% at the end of the operation. Two interim analyses were performed according to predefined stopping criteria allowing for design and sample size adaption. The primary endpoint was chronic pain defined on a visual analog scale (VAS) as >= 30 in any quality (at rest, lying, walking, climbing stairs, and bending over) 3 months postoperatively. A logistic regression model was built to compare the incidence of chronic pain using generalized estimating equations to adjust for clustering in bilateral hernias. Results. Among 357 patients, there were 406 hernias randomized. A total of 5.8% (10/173) experienced VAS >= 30 in any quality in the intervention group and 2.3% (4/174) in the placebo group (P = .114) at 3 months postoperatively. Multivariable analysis revealed no evidence of between-group differences for the development of any pain (odds ratio [OR], 1.03; 95% CI, 0.67-1.57; P = .905), whereas preoperative pain was an independent risk factor (OR, 2.52; 95% CI, 1.12-5.68; P = .025). Conclusion. We did not find any evidence that intraoperative infiltration of local anesthetic had an impact on the development of chronic postoperative pain.