Anthropometric Indices as Predictors of Coronary Heart Disease Risk: Joint Modeling of Longitudinal Measurements and Time to Event

Background: The prevalence of overweight and obesity have increased dramatically worldwide and together they constitute a major risk factor for coronary heart disease (CHD). The aim of this study was to assess the repeated mea-surements of body mass index (BMI), waist circumference (WC), waist to hip ratio (WHR) and waist to height ratio (WHtR) in predicting CHD incidence. Methods: This longitudinal study was conducted within the framework of the Tehran Lipid and Glucose Study be-tween 1999–2011, on 1959 women and 1371 men participants’ ages ≥30 yr, without a history of CVD. A joint model-ing approach was utilized for data analysis using R software. The resulting joint model allowed measuring α (quantifies the association between anthropometric indices up to time t and the hazard for CHD event at the same time point). Results: About 9% of the participants (7.1% of the women and 11.7% of the men) experienced CHD event during follow-up. The results indicated a significant linear increasing trend in BMI, WC, WHR, and WHtR over time (P<0.001). The increased risk of CHD event in females increases with the values of BMI (α= 0.004, P=0.023), WC (α= 0.018, P=0.009), WHR (α= 0.067, P=0.014) and WHtR (α= 0.106, P=0.002). Furthermore, in males the risk of CHD risk increases by the values of BMI (α= 0.005, P=0.032), WC (α= 0.019, P=0.008), WHR (α= 0.043, P=0.015) and WHtR (α= 0.096, P=0.002). Conclusion: By jointly modeling longitudinal data with time-to-event outcomes, our study revealed that WHtR is su-perior to other indices in predicting CHD incidence.