Brompton Harefield Infection Score (BHIS): development and validation of a stratification tool for predicting risk of surgical site infection after coronary artery bypass grafting.

OBJECTIVE

Surgical site infection (SSI) following coronary artery bypass grafting (CABG) is a serious complication associated with significant morbidity and mortality. Despite the substantial impact of SSI there is lack of a specific risk stratification tool to predict this complication after CABG. This study was undertaken to develop a specific prognostic scoring system for the development of SSI that could risk-stratify patients undergoing CABG.

METHODS

Between January 2009 and June 2012, continuous prospective surveillance data on SSI and a set of 41 variables were collected. Using binary logistic regression analysis we identified independent predictors of SSI. Initially we developed a predictive model in a subset of 769 patients. Dataset was expanded to 4087 cases and a final model and risk score were derived. Calibration of the scores was performed using the Hosmer-Lemeshow test.

RESULTS

The model had area under Receiver Operating Characteristic curve of 0.727 (0.827 for preliminary dataset). Baseline risk score incorporated independent predictors of SSI: female gender = 2 (p < 0.0001; RR 2.1), diabetes = 1 (p = 0.0098, RR 1.4) or HbA1c >7.5% = 3 (p < 0.0001; RR 3.4), body mass index ≥35 = 2 (p < 0.0001; RR 2.4), left ventricular ejection fraction < 45% = 1 (p = 0.0255; RR 1.4), and emergency surgery = 2 (p = 0.012; RR 2.4). A risk stratification system, the Brompton & Harefield Infection Score (BHIS) was developed.

CONCLUSION

BHIS effectively predicts SSI risk and may help with risk stratification in relation to public reporting and reimbursement as well as targeted prevention strategies in patients undergoing CABG.