Obesity and early complications after cardiac surgery

Objective: To assess the prevalence of obesity in patients undergoing coronary artery bypass grafting, heart valve surgery, or both procedures, and its association with postoperative outcomes. Design and setting: Retrospective analysis of data, collected by the Australasian Society of Cardiac and Thoracic Surgeons Victorian Cardiac Surgery Database Project, on patients undergoing coronary artery bypass grafting, heart valve surgery, or both procedures, between 1 June 2001 and 31 January 2006. Participants: 11736 patients divided into four groups: underweight (body mass index [BMI], < 20), normal weight (BMI, 20-30), obese (BMI, > 30 to < 40), and morbidly obese (BMI, >= 40). Main outcome measures: Prevalence of obesity (compared with the age- and sex-matched adult Australian population); associations between obesity and morbid obesity in cardiac patients and adverse postoperative outcomes. Results: 30.4% of patients had a BMI > 30 (28.6% obese, 1.8% morbidly obese) compared with an expected prevalence of 21.2%. Morbid obesity was associated with prolonged ventilation (adjusted odds ratio [OR), 2.4; 95% Cl, 1.6-3.7), readmission to intensive care (adjusted OR, 2.2; 95% Cl, 1.2-4.1), and length of stay > 14 days (adjusted OR, 2.1; 95% Cl, 1.4-3.3). Both obesity and morbid obesity were associated with renal failure (adjusted ORs, 1.4 [95% Cl, 1.1-1.7] and 2.9 [95% Cl, 1.7-4.9], respectively) and deep sternal wound infection (adjusted ORs, 2.4 [95% Cl, 1.5-3.8] and 7.2 [95% Cl, 2.8-18.7], respectively). Conclusions: Obesity is 1.4 times more prevalent in patients having coronary artery bypass grafting or heart valve surgery in Victoria compared with the general adult Australian population. Both obesity and morbid obesity are associated with early morbidity, but not mortality, after operation.