Obesity associated with lower use of RBC transfusions in cardiac surgery

A new study published in European Journal of Cardio-Thoracic Surgery suggests that obesity was not linked to 30-day mortality, however it was linked to less utilization of red blood cell transfusions in heart surgery.

Obesity increases the burden of cardiovascular risk factors, morbidity, and death. Several studies, however, have shown that obese patients have a better outcome after cardiac surgery than normal weight patients, a phenomenon known as the obesity paradox. Obesity has also been related to a lower demand for red blood cell transfusions. Jenni Räsänen and colleagues undertook this study to assess the influence of BMI on 30-day mortality and red blood cell transfusions in patients after heart surgery, a clinically significant subject with inconsistent previous findings.

The study included 1691 patients who underwent coronary, valve, or aortic root surgery with cardiopulmonary bypass between 2013 and 2016. The patients were classified according to their BMI using World Health Organization criteria. For the analysis, logistic regression with correction for relevant confounding variables was utilized.

The key findings of this study were:

1. 28.7% of the patients were normal weight, 43.3% were overweight, 20.5% were slightly obese, and 7.5% were extremely obese.

2. The 30-day death rate was 1.9%, with no statistically significant variations across body mass index groups. Red blood cell transfusions were administered to 41.0% of patients.

3. Overweight (odds ratio [OR] 0.75, 95% CI 0.56-0.99, P = 0.045), slightly (OR 0.65, 95% CI 0.46-0.92, P = 0.016), and severely obese (OR 0.41, 95% CI 0.24-0.70, P =0.001) patients required fewer red blood cell transfusions than normal weight patients.

Those with a greater BMI were less likely to require red blood cell transfusions. This finding supports earlier research that suggests larger-bodied individuals may have better surgical results.

Reference:

Räsänen, J., Ellam, S., Hartikainen, J., Juutilainen, A., & Halonen, J. (2023). Association of body mass index with 30-day mortality and red blood cell transfusions in open heart surgery. In European Journal of Cardio-Thoracic Surgery. Oxford University Press (OUP). https://doi.org/10.1093/ejcts/ezad162