Body mass index, cardiac surgery and clinical outcome. A single-center experience with 9125 patients

Background and AimThere is evidence for a J-shaped association between Body Mass Index (BMI) and all-cause mortality in general populations. In cardiac surgical patients, the effect of BMI on mortality and major adverse cardiac and cerebrovascular events (MACCE) is not completely clear.Methods and ResultsWe investigated the effect of BMI on MACCE (primary endpoint), as well as intensive care unit (ICU)-related outcomes and mid-term mortality in 9125 consecutive patients who were operated on at our institution between July 2009 and July 2012. Of the study cohort, 3.0% were underweight (BMI < 20 kg/m2), 28.0% had a normal BMI (20–24.99 kg/m2), 43.1% were overweight (BMI 25–29.99 kg/m2), 19.3% were obese (BMI 30–34.99 kg/m2), and 6.6% were severely obese (BMI ≥ 35 kg/m2). Compared with overweight patients (lowest incidence of MACCE), the multivariable-adjusted odds ratio of MACCE in severely obese patients was 1.39 (95% CI: 1.03–1.87). Underweight and severely obese patients had the longest risk-adjusted duration of mechanical ventilator support and ICU stay (P-values 0.004–0.001). The red blood cell concentrates requirement was highest in underweight patients (P < 0.001). Compared with normal and overweight patients, the multivariable-adjusted hazard ratio of 2-year mortality was higher in underweight patients (1.72 [95% CI: 1.26–2.36] and =2.07 [95% CI: 1.51–2.83], respectively), but did not differ significantly in severely obese patients.ConclusionData demonstrate that both severe obesity and underweight are independent risk factors for operative complications in cardiac surgical patients. With respect to mid-term survival, special attention should be paid to underweight patients scheduled for cardiac surgery.