Risk of morbidity and in-hospital mortality in obese patients undergoing coronary artery bypass surgery

OBJECTIVES: Obesity is often perceived to be a risk factor for adverse outcomes following coronary artery bypass graft (CABG) surgery. Several studies have been unclear about the relationship between obesity and the risk of adverse outcomes. The aim of this study was to examine the relationship between obesity and in-hospital outcomes following CABG, while adjusting for confounding factors. METHODS: A total of 4713 consecutive patients undergoing isolated CABG between April 1997 and September 2001 were retrospectively analyzed. Body mass index (BMI) was used as the measure of obesity and was grouped as non-obese (BMI or =35). Associations between obesity and in-hospital outcomes were assessed by use of logistic regression to adjust for differences in patient characteristics. RESULTS: A total of 3429 patients were defined as non-obese, compared to 1041 obese and 243 severely obese. There was no association between obesity and in-hospital mortality, stroke, myocardial infarction, re-exploration for bleeding and renal failure. Obesity was significantly associated with atrial arrhythmia (adjusted odds ratio (OR) 1.19, P = 0.037 for the obese; adjusted OR 1.52, P = 0.008 for the severely obese) and sternal wound infections (adjusted OR 1.82, P = 0.002 for the obese; adjusted OR 2.10, P = 0.038 for the severely obese). The severely obese patients were 4.17 (P < 0.001) times more likely to develop harvest site infections. Severely obese patients were also more likely to have prolonged mechanical ventilation and post-operative stays, compared to non-obese patients. CONCLUSIONS: Obese patients are not associated with an increased risk of in-hospital mortality following coronary artery bypass surgery. In contrast, there is a significant increased risk of morbidities and post-operative length of stay in obese patients compared to non-obese patients.