Impact of body mass index on the outcomes of patients after coronary artery bypass grafting

Aims: The effect of body mass index (BMI) on outcome after coronary artery bypass grafting (CABG) remains controversial. Methods: We retrospectively studied 4085 (elective, urgent, emergency) patients who underwent isolated CABG in our department during January 2000 until May 2005. The patients were devided into 4 groups: 1. BMI<20 (underweight, n=37); 2. BMI≥20–25 (normal weight, n=857); 3. BMI>25–30 (overweight, n=2242); 4. BMI>30 (obese, n=922). The perioperative data were statistically analysed. Results: Patients characteristics were similar in all groups, but the obese were 3 years younger at time of CABG. Mortality (p=0.047), rate of resternotomy and rate of reintubation were significantly lower in obese patients compared to normal weighted patients. The rate of neurologic complications was less in obese patients, but not statistically significant. Duration to extubation was also longer in obese patients, but not significant. In contrast, sternal wound infections occurred significantly more often in obese patients (p=0.020). Underweight Normal Overweight Obese Extubation (median, hours) 8 (p=0.26) 13 16 (p=0.30) 17 (p=0.001) Reintubation (%) 10.8 (p=0.17) 5.5 3.7 (p=0.027) 2.9 (p=0.007) Resternotomy (%) 5.4 (p=0.14) 1.9 1.5 (p=0.49) 0.5 (p=0.009) Neurology (%) 2.7 (p=0.12) 0.6 0.7 (p=0.69) 0.3 (p=0.41) Sternal wound infections (%) 2.7 (p=0.40) 6.0 5.1 (p=0.62) 9.0 (p=0.020) Conclusion: Obese patients did not have more complications following CABG compared to normal weight patients, the mortality rate was even lower in the obese patient group. However, the rate of sternal wound infection was significantly elevated.