Obesity Linked to Complications Following Coronary Artery Bypass

Patients with severe obesity (BMI ≥40 kg/m²) were 53% more likely to have complications within 30 days of coronary artery bypass graft (CABG) surgery and had a 3-fold higher risk of infection compared with patients without obesity (BMI 18.5-24.9 kg/m²), according to a new study.

“In addition, the median hospital stay was 1 day longer in patients with severe obesity compared to patients without obesity,” said study author Mary Forhan, PhD, of the Department of Occupational Therapy at the University of Alberta. “In patients with severe obesity, those who had diabetes and experienced an infection stayed 3.2 times longer days in hospital compared to patients without either condition.”
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The researchers analyzed data from 7560 patients who underwent CABG. Using BMI of 18.5-24.9 as a reference, the associations of 4 BMI categories (25.0-29.9, 30.0-34.9, 35.0-39.9, and ≥40.0) with rates of operative mortality, overall early complications, subgroups of early complications (ie, infection, and renal and pulmonary complications), and length of stay were assessed while adjusting for clinical covariates.

They saw no difference in operative mortality; however, the investigators observed higher risks of overall complications for patients with BMI 35.0-39.9 (adjusted odds ratio 1.35, 95% CI 1.11-1.63) and ≥40.0 (adjusted odds ratio 1.56, 95% CI 1.21-2.01). Subgroup analyses identified obesity as an independent risk factor for infection (BMI 30.0-34.9: adjusted odds ratio 1.60, 95% CI 1.24-2.05; BMI 35.0-39.9: adjusted odds ratio 2.34, 95% CI 1.73-3.17; BMI ≥40.0: adjusted odds ratio 3.29, 95% CI 2.30-4.71). Median length of stay was longer with BMI ≥40.0 than with BMI 18.5-24.9 (median 7 days vs. 6 days).

“Many studies have reported better prognosis in patients with obesity compared to patients without obesity (ie, the obesity paradox),” said lead study author Tasuku Terada, PhD, of the Department of Occupational Therapy at the University of Alberta. “Thus, our finding showing that patients with severe obesity spent a longer time in hospital compared to patients without obesity was interesting.”

The researchers said they attempted to identify potential risks associated with patients living with obesity undergoing cardiac surgery.

“While we showed infection is a potentially controllable risk factor in patients with severe obesity, our study did not determine types or locations of infections,” Terada said. “Future studies identifying infection types and locations in patients with severe obesity undergoing CABG may lead to the development of strategies to minimize the risk.”

—Mike Bederka

Reference:

Terada T, Johnson JA, Norris C, et al. Severe obesity is associated with increased risk of early complications and extended length of stay following coronary artery bypass grafting surgery [Published online June 1, 2016]. J Am Heart Assoc. doi: 10.1161/JAHA.116.003282.