Probabilistic model for prediction of angiographically defined obstructive coronary artery disease using electron beam computed tomography calcium score strata

Background-Electron beam CT (EBCT) is an accurate, noninvasive method to detect and quantify coronary artery calcification, a marker of coronary artery disease (CAD). This investigation examined the accuracy of EBCT to detect obstructive CAD (greater than or equal to 50% stenosis) and determined the optimal strata for quantity of coronary artery calcification to facilitate clinical decision-making. Methods and Results-Clinical research patients (n=213) were examined with coronary angiography and EBCT (angiography group), and 765 research participants were examined with only EBCT (nonangiography group). Of the angiography group, 53% had obstructive CAD. After adjustment for verification bias, the estimated sensitivity and specificity for calcium score greater than or equal to 1 were 97.0% and 72.4%, respectively. Likelihood ratios for strata of calcium score associated with obstructive CAD were calculated in each sex and 2 age groups. Among those greater than or equal to 50 years old, the same 4 strata of EBCT calcium scores were identified in each sex; likelihood ratios ranged from 0.03 (calcium score 0) to 12.85 (calcium score greater than or equal to 200). The same 3 strata of EBCT calcium scores were identified in each sex among those <50 years old; likelihood ratios ranged from 0.13 (calcium score 0) to 190 (calcium score greater than or equal to 100). Conclusions-A calcium score greater than or equal to 200 among those greater than or equal to 50 years old and calcium score greater than or equal to 100 among those <50 years old provided strong evidence that patients of either sex had obstructive CAD. A calcium score of O provided strong evidence that patients greater than or equal to 50 years old did not have obstructive CAD.