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 ß 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.

Occupational mechanical exposures and reoperation after first-time inguinal hernia repair: a prognosis study in a male cohort.

PURPOSE: The aim of this study was to evaluate exposure-response relationships between occupational mechanical exposures and risk of reoperation after inguinal hernia repair. METHODS: Using register information, we identified all men born in Denmark 1938-1988, who had their first inguinal hernia repair 1998-2008, and who were 18-65 years old and active in the labour market at the time of surgery. The Danish Hernia Database provided information on repairs and reoperations. We used registered occupational codes and a job exposure matrix based on experts' ratings to estimate total load lifted per day, frequency of heavy lifting, and number of hours per day spent standing/walking. We also obtained register information on sickness absence. Multivariable Cox regression analysis was used. RESULTS: The cohort comprised 34,822 patients. We did not reveal exposure-response relationships between occupational mechanical exposures and the hazard ratio (HR) of reoperation. The percentage of patients with >2 weeks of sickness absence within 8 weeks after surgery increased with total load lifted per day from 15 to 53%. Longer sickness absence was associated with an increased HR of reoperation, but within strata of sickness absence, we found no increase in the HR of reoperation with increasing exposures. CONCLUSION: We did not find indications that the HR of reoperation was related to occupational mechanical exposures, even after accounting for a potential protective effect of sickness absence. Hence, the exposure-related prolonged duration of sickness absence could not be explained by exposure-related complications that led to reoperation.