Inguinal hernia repair among men: development and validation of a preoperative risk score for persistent postoperative pain.

Purpose: Persistent postoperative pain (PPP) is a prevalent complication after inguinal hernia repair. The aim of this study was to develop and validate a preoperative risk score for PPP.

Methods: We developed the risk score based on a cohort of 2,508 Danish men, who answered a questionnaire six months after inguinal hernia repair performed 2015-2016. PPP was defined as a numerical rating scale score ≥ 2 during activity six months postoperatively. Logistic regression analyses were undertaken to determine statistically significant predictors of PPP. Univariable analysis selected potential predictors with a p value ≤ 0.20, and a subsequent multivariable model was built using backward elimination with a criterion of p value < 0.10. We created a risk score based on the β coefficients of the multivariable model. The risk score was validated internally using Hosmer-Lemeshow goodness of fit test, calibration belt test, and receiver operating characteristic curve analyses with 95% confidence intervals based on the bootstrap analysis. External validation was performed in a cohort of 293 men recruited preoperatively.

Results: Predictors of PPP were age 18-49 and 50-59 (versus ≥ 60) years (p < 0.001), total load lifted > 1,000 kg/day (p = 0.001), working in a bent-over position > 1 h/day (p < 0.001), leisure-time physical activity < 2 h/week (p = 0.009), increasing body mass index (per unit) (p < 0.003), and repair of recurrent hernia (p = 0.001).The preoperative risk score predicted risks of 6-61% in the development population. The model showed good internal and external validity.

Conclusion: The results suggest that the risk of PPP after inguinal hernia repair can be predicted using a preoperative risk score.