Effect of Body Mass Index on Outcomes After Cardiac Surgery: Is There an Obesity Paradox?

doi:10.1016/j.athoracsur.2010.08.047

The Annals of Thoracic Surgery

Volume 91, Issue 1, January 2011, Pages 42-47

https://doi.org/10.1016/j.athoracsur.2010.08.047 Get rights and content

Background

Numerous studies have documented an obesity paradox in which overweight and obese people with cardiovascular disease have a better prognosis compared with patients with normal body mass index (BMI). This study sought to quantify the effect of BMI on clinical outcomes after cardiac surgery and investigate the obesity paradox.

Methods

A concurrent cohort study of 2,440 consecutive patients undergoing cardiac surgery (coronary artery bypass grafting [CABG], valve, or CABG and valve surgery) from January 2004 to December 2008 was carried out. The patients were divided into three groups on the basis of BMI: normal weight (BMI 18.5 to 24.9; n = 556; 23%), overweight (BMI 25.0 to 29.9; n = 965; 39%), and obese (BMI ≥ 30; n = 919; 38%). Multivariable analyses and propensity score matching were used to compare the early and late clinical outcomes among the different BMI groups.

Results

Overweight patients had a lower operative mortality (odds ratio, 0.4; 95% confidence interval, 0.2 to 0.9; p = 0.031) compared with normal BMI patients. Obese patients had a comparable risk for operative mortality (odds ratio, 0.8; 95% confidence interval, 0.4 to 1.6; p = 0.47) compared with normal-weight patients. Actuarial 5-year survival was better for the overweight (hazard ratio, 0.5; 95% confidence interval, 0.4 to 0.8; p = 0.002) and comparable for the obese (hazard ratio, 0.9; 95% confidence interval, 0.5 to 1.4; p = 0.49) groups compared with the normal-weight patients.

Conclusions

Overweight patients have better early hospital outcomes and improved survival after cardiac surgery compared with normal BMI patients, supporting the obesity paradox.

Section snippets

Patients

The database of the Division of Cardiothoracic Surgery at the Sanger Heart and Vascular Institute was queried and identified 2,465 patients who underwent coronary artery bypass grafting (CABG), valve, or CABG and valve surgery from January 2004 to December 2008. There were 25 underweight patients who were excluded from the study because of the small number of patients to allow valid comparisons. The patients (n = 2,440) were divided in three groups based on the Society of Thoracic Surgeons' BMI

Preoperative Characteristics

Preoperative patient characteristics are shown in Table 1. Overweight patients were more likely to be younger males and have diabetes, hypertension, congestive heart failure, lower ejection fraction, arrhythmia, and three-vessel coronary artery disease compared with normal BMI patients. Obese patients were more likely to be younger males and have diabetes, congestive heart failure, hypertension, history of acute myocardial infarction, and three-vessel coronary artery disease compared with

Comment

Obesity has been increasing in epidemic proportions and has become a critical problem in the United States [14, 15]. Although obesity has been implicated as one of the major risk factors for coronary heart disease, previous evidence indicates an obesity paradox in that overweight and obese patients with cardiovascular disease seem to have a more favorable short-term and long-term prognosis than underweight patients. In four trials of 49,055 patients with cardiovascular disease, the event rate

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Original articleAdult cardiacEffect of Body Mass Index on Outcomes After Cardiac Surgery: Is There an Obesity Paradox?

Background

Methods

Results

Conclusions

Section snippets

Patients

Preoperative Characteristics

Comment

J Am Coll Cardiol

J Am Coll Cardiol

Am J Cardiol

Lancet

Am J Cardiol

J Am Coll Cardiol

Am J Med

Am Heart J

J Am Coll Cardiol

Public Health

Chest

Am Heart J

J Am Coll Cardiol

Original article
Adult cardiac
Effect of Body Mass Index on Outcomes After Cardiac Surgery: Is There an Obesity Paradox?