Diagnostic accuracy of pre-test probability combined with computed tomographic coronary angiography in patients suspected for stable coronary artery disease

Objective To compare the performance of updated Diamond-Forrester method (UDFM) and Duke clinical score (DCS) in patients with stable angina pectoris and assess the combined application of pre-test probability and computed tomographic coronary angiography (CTCA) in these patients. Methods Five hundred and twenty-three symptomatic patients who underwent both CTCA and conventional coronary angiography (CCA) in 2 weeks in Chinese PLA General Hospital from January 2012 to December 2013 were enrolled in this study. The pre-test probability was determined using UDFM and DCS for each patient. Receiver operating characteristics (ROC) curves were used to compare two models. The diagnostic accuracy of CTCA for detecting coronary artery disease (CAD) was compared with CCA. The estimated post-test probability was calculated by Bayesian statistics. Results Of the 523 patients, 385 (74%) were positive tested by CCA. Compared with UDFM, DCS reclassified more positive patients into high group (46% for DCS vs. 23% for UDFM, P< 0.000 1). The areas under ROC curves (AUC) for DCS was significantly greater than that for UDFM0.77 (0.73, 0.82) vs 0.71 (0.66, 0.77), P=0.000 9. In patient-based evaluation by CTCA, three pre-test probability groups according to DCS revealed a sensitivity of 94%, 98% and 97%, a specificity of 94%, 87% and 55%, a positive predictive value (PPV) of 91%, 94% and 93%, and a negative predictive value (NPV) of 96%, 96% and 77%, respectively. The estimated post-test probabilities corresponded well with the observed one, especially for the intermediate estimated pre-test probability group (positive:94.7% vs 93.6%, negative:3.7% vs 4.0%). Conclusion Compared with UDFM, DCS has a better performance in calculating pretest probabilities in patients with stable angina pectoris. In addition, the combined application of DCS and CTCA can avoid unnecessary tests.