Introduction: Obesity is associated with multiple CVD risk factors as well as coronary artery calcium (CAC). CAC is a strong predictor of CHD and CVD mortality. It would then seem intuitive that an elevated BMI would be associated with higher risk for mortality but studies evaluating this association have frequently shown paradoxical results.
Methods: The CAC Consortium is a multi-centered cohort of 66,636 individuals free of established CVD who underwent non-contrast cardiac-gated CAC testing for clinical indications. We included patients with data available to calculate BMI at the baseline assessment. Mortality was assessed through linkage to the Social Security Death Index and cause of death was obtained from the National Death Index. Multivariable logistic regression was used to determine odds ratios (OR) for CAC according to clinically relevant BMI categories. Cox proportional hazards regression modeling was be used to determine hazard ratios (HR) to assess the relationship between BMI and CHD, CVD, and total mortality.
Results: Our sample included 36,509 individuals (mean age 54.1 +/- 10.3 years, 34.4% female). Over a median 11.4 (IQR 9.3-12.6) years of follow up there were 1,550 deaths (4.3% of sample). Compared to individuals with a normal BMI (21- <25 kg/m2), the odds of CAC>0 were increased in individuals who were overweight (BMI 25- <30 kg/m2, OR 1.13 [95% CI 1.1-1.2]) and in those who were obese (BMI > 30 kg/m2, OR 1.5 [95% CI 1.4-1.6]). During follow-up, individuals who were obese were at increased risk for CHD, CVD, and total mortality while those who were overweight at baseline did not have a significant increase in risk for mortality (Table).
Conclusion: In a large multicenter cohort of individuals undergoing CAC scoring we did not find evidence of an obesity paradox as individuals who were overweight and obese were more likely to have CAC and obese individuals were at higher risk for CHD, CVD, and all-cause death during follow-up.