Body mass index and mortality in patients with severe coronary artery diseases: A cohort study from China

Background and aims It is still controversial whether obesity and overweight increase the risk of mortality for patients with coronary artery disease. The current study aimed to investigate the relationship between body mass index (BMI) and mortality in patients with triple-vessel disease (TVD). Methods and results From April 2004 to February 2011, 8943 patients with angiographically confirmed TVD were consecutively enrolled. Patients were divided into five groups according to BMI: underweight (<18.5 kg/m2), normal weight (18.5–23.9 kg/m2), overweight: (24–27.9 kg/m2), mild obesity (28–31.9 kg/m2), and severe obesity (≥32 kg/m2). The primary end point was all-cause death. Subgroup analysis was performed for treatment strategies: revascularization and medical treatment alone. During a median follow-up of 7.5 years, lower risks of mortality were observed in patients with overweight (adjusted HR 0.85, 95% CI 0.75–0.97) and mild obesity (adjusted HR 0.83, 95% CI 0.69–1.00) compared to those with normal weight. Polynomial Cox regression suggested a U-shape association between BMI and adjusted mortality risk. In the revascularization subgroup, there was a significantly higher mortality risk in patients with severe obesity (adjusted HR 1.57, 95% CI 1.03–2.40) than in those with normal weight. While in the medical treatment subgroup, mortality risk decreased as BMI increased, with the lowest risk being observed in patients with severe obesity. Conclusion There is a U-shape relationship between BMI and all-cause death in patients with TVD, with increased risks among both underweight and severely obese patients. This relationship may be influenced by treatment strategies.