Role of pre-operative red cell distribution width estimation in the prediction of in-hospital mortality after off-pump coronary artery bypass grafting

BACKGROUND Red cell distribution width (RDW) level is routinely provided in a simple and inexpensive complete blood count report. However, RDW is sometimes overlooked. Recently a higher RDW level is found associated with postoperative mortality after off-pump coronary artery bypass. Many risk-prediction tools are available, like the European System for Cardiac Operative Risk Evaluation, Society of Thoracic Surgeons score, etc. but all need improvement for better prediction. So, a new risk-factor should be discovered which is simple enough for clinical use and cost-effective, and improves the risk assessment tools that help to predict and avoid preventable mortality following cardiac surgery. METHODS The prospective study was conducted, taking a total of 150 patients of coronary artery disease who underwent elective isolated off-pump coronary artery bypass. The study population was grouped according to their preoperative RDW level as Group A (RDW ≤ 14%), Group B (RDW 14-16%), and Group C (RDW ≥ 16%). The receiver operating characteristic (ROC) curve was constructed and multivariate regression analysis was done to see the predictive value of RDW for in-hospital mortality. RESULTS The mortality rate was 2.7%, N = 150. ROC curve revealed Area Under the Curve 0.841 and p = 0.020 that indicates the RDW as the reliable predictor for in-hospital mortality. Multivariate regression analysis showed the RDW to be the only variable independently predicting in-hospital mortality after off-pump coronary artery bypass among possible haematological predictors. (OR 1.838, 95% CI 1.061-3.186, p = 0.030). CONCLUSION Preoperative raised RDW level is a novel predictor of in-hospital mortality after off-pump coronary artery bypass. Further studies should be done to determine the associated mechanism.