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Mortality after cardiac surgery lower in patients with obesity
After cardiac surgery, patients with obesity had lower risks for mortality vs. patients in the underweight and normal-weight groups, researchers reported.
The researchers performed multiple analyses to address residual confounding and reverse causation and found the results were consistent.
Researchers in the United Kingdom and Italy used data from the National Adult Cardiac Surgery registry covering all cardiac surgical procedures completed between April 2002 and March 2013. A parallel systematic review and meta-analysis evaluating studies through June 2015 on Medline, Embase, Scopus and Cochrane Library was also conducted.
Researchers categorized 401,227 adult patients into six groups based on BMI. Groups were defined using the WHO classification system.
Regarding the primary endpoint of mortality after cardiac surgery, 11,511 patients died in the hospital (3.29%; 95% CI, 3.23-3.34), according to the findings.
Among patients categorized as underweight, mortality was 8.5%. In those with normal weight, mortality was 4.4%. Among patients with overweight, mortality was 2.7%. In patients with obesity class I or II, mortality was 2.8%. And in patients with obesity class III, mortality was 3.7%.
Similar findings to the primary analysis were noted in fractional polynomial, restricted cubic spline and propensity score analyses, the researchers wrote.
Compared with patients with normal weight, patients with overweight (adjusted OR = 0.79; 95% CI, 0.76-0.83) class I obesity (adjusted OR = 0.81; 95% CI, 0.76-0.86) and class II obesity (adjusted OR = 0.83; 95% CI, 0.74-0.94) were less likely to die after cardiac surgery, while underweight patients (adjusted OR = 1.51; 95% CI, 1.41-1.62) were more likely to die, the researchers wrote.
They found the protective effects of obesity to be less in patients with severe chronic renal, lung or cardiac disease. The protective effects of obesity were greater in older patients, as well as in patients with complications of obesity such as metabolic syndrome and atherosclerosis. When adjustments were made for important confounders, the results did not change.
“These findings highlight knowledge gaps that must be addressed by further research.
They identify a high-risk cohort, patients with low BMI, who could potentially benefit from targeted weight-gain interventions prior to surgery. They also challenge current practice where obese patients are rejected for, or advised to lose weight prior to, major surgery,” Giovanni Mariscalco, MD, PhD, from the Leicester Cardiovascular Biomedical Research Unit at Glenfield Hospital, Leicester, England, and colleagues wrote. – by Suzanne Reist
Disclosure: The researchers report no relevant financial disclosures.