Longitudinal cohort study on preoperative pain as a risk factor for chronic postoperative inguinal pain after groin hernia repair at 2-year follow-up.

PURPOSE To assess the rate of late chronic postoperative inguinal pain (CPIP) after groin hernia repair in patients with different categories of preoperative VRS (Verbal Rating Scale) pain and to make a pragmatic evaluation of the rates of potentially surgery-related CPIP vs. postoperative continuation of preexisting preoperative pain. METHODS Groin pain of patients operated from 01/11/2011 to 01/04/2014 was assessed preoperatively, postoperatively and at 2-year follow-up using a VRS-4 in 5670 consecutive groin hernia repairs. A PROM (Patient Related Outcomes Measurement) questionnaire studied the impact of CPIP on the patients' daily life. RESULTS Relevant (moderate or severe VRS) pain was registered preoperatively in 1639 of 5670 (29%) cases vs. 197 of 4704 (4.2%) cases at the 2-year follow-up. Among the latter, 125 (3.7%) cases were found in 3353 cases with no-relevant preoperative pain and 72 (5.3%) in 1351 cases with relevant preoperative pain. Relevant CPIP consisted of 179 (3.8%) cases of moderate pain and 18 (0.4%) cases of severe pain. The rate of severe CPIP was independent of the preoperative VRS-pain category while the rate of moderate CPIP (3.1%, 3.4%, 4.1%, 6.8%) increased in line with the preoperative (none, mild, moderate, and severe) VRS-pain categories. The VRS probably overestimated pain since 71.6% of the relevant CPIP patients assessed their pain as less bothersome than the hernia. CONCLUSION At the 2-year follow-up, relevant CPIP was registered in 4.2% cases, of which 63.5% were potentially surgery-related (no-relevant preoperative pain) and 36.5% possibly due to the postoperative persistence of preoperative pain. The rate of severe CPIP was constant around 0.4%.