| Coronary heart disease (CHD), one of the leading causes of cardiovascular morbidity and mortality in the United States (US), is linked to many risk factors among them obesity, which has become a health concern due to its increased prevalence. Obesity, commonly measured by the body mass index (BMI), is caused by a complex network of physiologic, genetic, environmental, and behavioral factors. Estimates about the association between BMI and the incidence of CHD are lacking at the national level in the US. In this study that aimed at investigating the association between BMI and the incidence of CHD, the objectives were: 1) to determine the incidence of CHD in the US population and across race and sex; 2) to estimate the effects of BMI on the risk of CHD in the US population and across race and sex.;Data from the First National Health and Nutrition Examination Survey Epidemiologic Follow-up Study (NHEFS) were analyzed. Incidence of CHD was calculated both as cumulative incidence and incidence density (ID). In addition to the standard Cox proportional hazard model, estimates of the effect of BMI on the risk of CHD were evaluated by taking into account the variation of covariates over time and the concept of competing risk of death while adjusting for demographic, medical history, and behavioral covariates.;After an average 16-year follow-up, 382 incident cases of CHD were recorded among 6,346 selected participants. The cumulative incidence was 99.3 in the general population, 134.6 in men, and 70.0 in women, per 1,000 population. The ID, per 1,000 person-years, was 3.68 in the general population, 4.99 in men, and 2.66 in women. The relative risk (RR) and 95% confidence interval (CI) of developing a CHD event based on BMI and after controlling for socio-demographic, medical history, and behavioral characteristics was 1.05 [1.03, 1.07] in standard Cox modelling, in Cox extension with time-varying covariates, and in Fine-Gray modeling. The RR and 95% CI of CHD events among Whites as compared to non-Whites was 1.20 [0.88, 1.63] in the first two modeling techniques and 1.34 [0.99, 1.83] for Fine-Gray. The RRs and 95% CIs of developing a CHD event for females as opposed to males for the three modeling approaches were 0.44 [0.35, 0.54]; 0.44 [0.35, 0.54]; and 0.48 [0.39, 0.60] respectively. Comparison of coefficients estimates and their standard errors for the three modeling techniques yielded a P-value >.05.;An association was found between BMI and the incidence of CHD. While race had no effect on the occurrence of CHD, the incidence of that condition was higher among males as compared to females. The risk of developing a CHD event increased of 5% for each unit increase of BMI. Women had a lower risk of developing a CHD event as opposed to men whereas Whites had the same risk as non-Whites of experiencing a CHD event. Variation of covariates over time and the presence of competing risk of death had no influence on the estimates of the relationship between BMI and the risk of CHD. |
