Examining the Influence of Waist Circumference in Cardiovascular Disease Risk Prediction Modeling
Cardiovascular disease (CVD) is the leading cause of non-communicable disease and pre-mature death worldwide. Waist circumference (WC) is a measure of abdominal adiposity that is strongly related to both CVD and all-cause mortality. However, WC is not routinely measured in clinical practice. Predicting which individuals will develop disease is a fundamental aspect to modern healthcare. To date, there is limited research examining whether adding WC to current risk prediction models will improve how well the model identifies individuals at risk for future disease. Therefore, the purpose of this thesis is to investigate whether the addition of WC improves CVD and all-cause mortality risk prediction compared to current models. We analyzed data from 34,377 men and 9,477 women who completed a baseline examination at the Cooper Clinic (Dallas, TX) during 1977 – 2003 and enrolled in the Aerobics Center Longitudinal Study (ACLS). Participants were followed until mortality or December 31st, 2003. WC was measured at the level of the umbilicus and other health risk factors including blood pressure, blood lipids, smoking, and diabetes were collected using standardized methods. Our primary finding was that the addition of WC does not improve risk prediction for fatal CVD, non-fatal CVD and all-cause mortality. This observation remained consistent across several statistical strategies to assess model performance. However, WC was significantly associated with the outcomes beyond common clinical risk factors. The findings of this thesis demonstrate that although WC is significantly associated with pre-mature death, adding WC to established risk prediction models does not improve how well the model is able to identify which individuals are at increased risk for future disease.