Predictive risk factors for persistent postherniotomy pain.

Background: Persistent postherniotomy pain (PPP) affects everyday activities in 5-10% of patients. Identification of predisposing factors may help to identify the risk groups and guide anesthetic or surgical procedures in reducing risk for PPP.

Methods: A prospective study was conducted in 464 patients undergoing open or laparoscopic transabdominal preperitoneal elective groin hernia repair. Primary outcome was identification of risk factors for substantial pain-related functional impairment at 6 months postoperatively assessed by the validated Activity Assessment Scale (AAS). Data on potential risk factors for PPP were collected preoperatively (pain from the groin hernia, preoperative AAS score, pain from other body regions, and psychometric assessment). Pain scores were collected on days 7 and 30 postoperatively. Sensory functions including pain response to tonic heat stimulation were assessed by quantitative sensory testing preoperatively and 6 months postoperatively to assess nerve damage.

Results: Four hundred sixty-four patients were included, whereof 442 were examined at 6 months (95.3% follow-up). Fifty-five patients (12.4%) had "moderate/severe" PPP at 6 months. Logistic regression analysis identified four risk factors for PPP: preoperative AAS score, preoperative pain to tonic heat stimulation, 30-day postoperative pain intensity, and sensory dysfunction in the groin at 6 months (nerve damage) (all P < 0.03). A risk prediction model of only preoperative factors and choice of surgical technique revealed increased preoperative AAS score, increased preoperative pain to heat stimulation, and open surgery to increase the risk for PPP (all P < 0.02).

Conclusion: PPP is related to both patient and surgical factors. Patients with a high preoperative AAS score and high pain response to a standardized heat stimulus may preferably be treated using an operative technique with lowest risk for nerve damage.