Purpose: To investigate the use of electron beam tomography (EBT) screening to predict all-cause mortality in a large cohort of asymptomatic women and men.
Methods and results: We obtained mortality information from the National Death Index in 10377 asymptomatic individuals (40% women) referred by primary care physicians for coronary calcification screening. The average follow-up period was 5 +/- 3.5 years. Univariable and multivariable Cox proportional hazard models were developed to predict all-cause mortality. Women had a lower prevalence of coronary calcification and smaller calcification scores than men (p < 0.0001). Death rates were higher among older, diabetic, hypertensive, and currently smoking individuals both in women and in men. In unadjusted (chi-square = 82, p < 0.0001) as well as risk-adjusted (chi-square = 7, p = 0.007) Cox survival models, women had a greater probability of death than men in each strata of calcification. Relative risk (RR) ratios were increased 3.0-fold, 5.5-fold, and 5.5-fold, respectively, for women compared with men with coronary calcification scores of 101-399, 400-1000, and >1000 (p < 0.0001). Using receiver operating characteristics (ROC) curve analyses to assess coronary calcification added incremental prognostic value to Framingham risk scores (p < 0.0001).
Conclusions: In this cohort of asymptomatic women, coronary calcification screening provided incremental prognostic information after adjustment for traditional risk factors. EBT may be a useful tool for risk stratification in women, where the early diagnosis of coronary heart disease (CHD) remains a strong challenge.