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%.