External validation of the ventral hernia risk score for prediction of surgical site infections.

Liang, Mike K; Goodenough, Christopher J; Martindale, Robert G; Roth, J Scott; Kao, Lillian S

BACKGROUND Previously, we reported that the Ventral Hernia Risk Score (VHRS) was more accurate in a Veterans Affairs (VA) population in predicting surgical site infection (SSI) after open ventral hernia repair (VHR) compared with other models such as the Ventral Hernia Working Group (VHWG) model. The VHRS was developed using single-center data and stratifies SSI risk into five groups based on concomitant hernia repair, skin flaps created, American Society of Anesthesiologists (ASA) score ≥3, body mass index ≥40 kg/m(2), and incision class 4. The purpose of this study was to validate the VHRS for other hospitals. METHODS A prospective database of all open VHRs performed at three institutions from 2009-2011 was utilized. All 436 patients with a follow-up of at least 1 mo were included. The U.S. Centers for Disease Control and Prevention (CDC) definition of SSI was utilized. Each patient was assigned a VHRS, VHWG, and CDC incision classification. Receiver-operating characteristic curves were used to assess predictive accuracy, and the areas under the curve (AUCs) were compared for the three risk-stratification systems. RESULTS The median follow-up was 20 mos (range 1-49 mos). During this time, 111 patients (25.5%) developed a SSI. The AUC of the VHRS (0.73; 95% confidence interval [CI] 0.67-0.78) was greater than that of the VHWG (0.66; 95% CI 0.60-0.72; p<0.01) and the CDC incision class (0.68; 95% CI 0.61-0.74; p<0.05). CONCLUSIONS The VHRS provides a novel, internally and externally validated score for a patient's likelihood of developing a SSI after open VHR. Elevating skin flaps, ASA score ≥3, concomitant procedures, morbid obesity, and incision class all independently predicted SSI. It remains to be determined if pre-operative patient selection and risk reduction, surgical techniques, and post-operative management can improve outcomes in the highest-risk patients. The VHRS provides a starting point for key stakeholders to discuss the management of ventral hernias.