Body mass index and clinical outcomes in patients with diabetes and stable coronary artery disease in THEMIS

Abstract Background Physiologic changes due to extremes of body weight may affect the efficacy and tolerability of antiplatelet treatment. However, it remains unclear whether the risks and benefits of intensified antiplatelet therapy among patients with diabetes and stable coronary artery disease (CAD) are affected by body mass index (BMI). Purpose To assess the relationship between baseline BMI and major adverse cardiovascular (CV) events, and to determine if the effects of ticagrelor vs. placebo varied across the BMI spectrum, in patients with diabetes and stable CAD. Methods THEMIS was a randomized, controlled trial of 19,220 individuals aged ≥50 years with type 2 diabetes and stable CAD, randomly allocated to ticagrelor or placebo on top of aspirin. Patients with a prior myocardial infarction (MI) or stroke, or already on dual antiplatelet therapy, were excluded. The primary efficacy outcome was a composite of CV death, MI, or stroke. The primary safety outcome was TIMI major bleeding. We examined prognostic implications of BMI using 1) restricted cubic splines for the overall trends with outcomes; 2) Cox regression models with predefined BMI intervals (<25 kg/m2, 25-29.9 kg/m2, and ≥30 kg/m2) adjusted for demographic, clinical, and laboratory variables; and 3) Cox regression models for the effects of ticagrelor vs. placebo on outcomes across the spectrum of BMI values (test for interaction). A two-sided P-value <0.01 was considered statistically significant to control the overall chance of type I errors. Results BMI was available in 19,202 (99.9%) participants, with a median of 29 kg/m2 (interquartile range: 26-33). A total of 3352 (17.5%) individuals had a BMI <25 kg/m2, 7644 (39.8%) had a BMI 25-29.9 kg/m2, and 8206 (42.7%) had a BMI ≥30 kg/m2. Median follow-up was 39.9 months (range 0-57), with 1554 primary efficacy events and 306 primary safety events occurring over the course of the study. BMI was not associated with the primary efficacy or safety outcome, or with their individual components. However, BMI was significantly associated with hospitalization for heart failure (HHF) (BMI <25 kg/m2: reference; hazard ratio [HR] for BMI 25-29.9 kg/m2: 1.07, 95% confidence interval [CI], 0.82 to 1.40; HR for BMI ≥30 kg/m2: 1.41, 95% CI, 1.07 to 1.84) and with the composite of HHF or CV death (comparable estimates) after multivariable adjustment (Figure). BMI was also significantly, positively associated with serious adverse events (BMI <25 kg/m2: reference; HR for BMI 25-29.9 kg/m2: 0.99, 95% CI, 0.93 to 1.06; HR for BMI ≥30 kg/m2: 1.20, 95% CI, 1.12 to 1.29). BMI did not modify the risks and benefits of ticagrelor vs. placebo. Conclusions BMI was independently associated with the risk of HHF and the composite of HHF or CV death, but not with other efficacy or safety outcomes, in patients with stable CAD and type 2 diabetes. Ticagrelor was of similar benefit on the primary efficacy outcome vs. placebo across the full range of BMI.