Effect of body mass index on early and late mortality after coronary artery bypass grafting.

Background: The effect of obesity on the long-term outcome after coronary artery bypass graft surgery (CABG) remains controversial. We analyzed data of patients undergoing CABG in a single center, to determine the predictive value of body mass index in combination with comorbidities on early and late mortality.

Methods: Early and late mortality of consecutive patients undergoing isolated CABG from January 1998 until December 2007 were determined. Patients were classified into five groups according to preoperative body mass index: underweight, normal weight, overweight, obese, and morbidly obese.

Results: After excluding 122 patients who were lost to follow-up and 236 patients with missing preoperative body mass index, 10,268 patients were studied. Multivariate logistic regression analyses showed that underweight was associated with higher early mortality (hazard ratio 2.63; 95% confidence interval: 1.13 to 6.11, p = 0.025). Multivariate Cox regression analyses did reveal morbid obesity as an independent predictor of late mortality (hazard ratio 1.67, 95% confidence interval: 1.15 to 2.43, p = 0.007).

Conclusions: Among patients undergoing isolated CABG, underweight is an independent predictor for early mortality, and morbid obesity is an independent predictor for late mortality.