Preoperative Leukocyte Counts Increase Risk of Adverse Outcomes in Obese Patient Undergoing Cardiac Surgery.

Obesity is a chronic inflammatory state associated with increased postoperative morbidity in patients undergoing cardiac surgery. In this study, we sought to determine whether the white blood cell (WBC) response may be an additional predictor for postoperative morbidities in obese patients undergoing cardiac surgery. A total of 1,171 consecutive patients who underwent cardiac surgery were retrospectively reviewed. Patients were divided into three groups based on their body mass index (BMI): non-obese (BMI < 30 kg/m²), obese (BMI 30-34.9 kg/m²) and severely obese (BMI ≥ 35 kg/m²). We used serial WBC count as an index of inflammation. Postoperative infection rate and postoperative hospital and intensive care unit (ICU) lengths of stay (LOS) were the primary endpoints. Obese and severely obese patients had significantly higher preoperative WBC counts and greater changes from the baseline at 24 h post-operation (P < 0.01). Obese and severely obese patients had significantly higher postoperative infection rate (P < 0.01). The postoperative LOS was significantly longer in severely obese patients (P = 0.03), and the ICU LOS was significantly longer in severely obese patients compared to non-obese patients (P = 0.02). Using logistic regression analysis, we identified the preoperative WBC count as an independent predictor for longer ICU stay and higher postoperative infection rate, and changes in WBC from preoperative baseline as a predictor for postoperative length of hospital stay in addition to BMI. Obese patients have increased postoperative morbidity after cardiac surgery. In addition to BMI, preoperative WBC count and the increase in WBC from the baseline in the immediate postoperative period are independent predictors for postoperative adverse outcomes.