Effect of postoperative analgesia on acute and persistent postherniotomy pain: a randomized study

• Nonsteroidal anti-inflammatory drugs or weak opioids have the same effectiveness in acute pain relief and in persistent postsurgical pain incidence after open inguinal hernia repair.
• The choice between them should be driven by their potential side effects.
• Early-starting (intraoperative) analgesia targeting different pain pathway as well as maintenance of analgesia (despite low-invasive surgery) after hospital discharge could help in preventing persistent postsurgical pain.
• Studies investigating the effect of different nonsteroidal anti-inflammatory drugs and patient's basal inflammatory status are suggested to get to an individualized therapy.

Study objectiveThe study objective is to identify differences in postoperative pain management according to different analgesic treatments, targeting 2 main pathways involved in pain perception.DesignThe design is a randomized, parallel groups, open-label study.SettingThe setting is in an operating room, postoperative recovery area, and surgical ward.PatientsThere are 200 patients undergoing open inguinal hernia repair (IHR) with tension-free technique (mesh repair).InterventionsThe intervention is a randomization to receive ketorolac (group K) or tramadol (group T) for 3 days after surgery.MeasurementsThe measurements are differences in analgesic efficacy (numeric rating scale [NRS]) in the postoperative (up to 5 days) period, chronic pain incidence (1 and 3 months), side effects, and complications.Main resultsWe found no differences in analgesic efficacy (NRS value ≥ 4 in the first 96 hours: 26% in group K vs 32% in group T, P = .43); the proportion of patients with NRS ≥ 4 was similar in both groups, and the time trajectories were not significantly different (P for interaction = .24). Side effects were higher (12% vs 6%) in the tramadol group, although not significantly (P = .14), with a case of bleeding in the ketorolac group and higher incidence of constipation in tramadol group. One patient in each group developed chronic pain.ConclusionsKetorolac or weak opioids are equally effective on acute pain and on persistent postsurgical pain development after IHR, and drug choice should be based on their potential side effects and patient's comorbidities. Further studies are needed to standardize the most rational approach to prevent persistent postsurgical pain after IHR.