Objective To determine whether a 3×2 table, using an intention to diagnose approach, is better than the "classic" 2×2 table at handling transparent reporting and non-evaluable results, when assessing the accuracy of a diagnostic test.Design Based on a systematic search for diagnostic accuracy studies of coronary computed tomography (CT) angiography, full texts of relevant studies were evaluated to determine whether they could calculate an alternative 3×2 table. To quantify an overall effect, we pooled diagnostic accuracy values according to a meta-analytical approach.Data sources Medline (via PubMed), Embase (via Ovid), and ISI Web of Science electronic databases. Eligibility criteria Prospective English or German language studies comparing coronary CT with conventional coronary angiography in all patients and providing sufficient data for a patient level analysis.Results 120 studies (10 287 patients) were eligible. Studies varied greatly in their approaches to handling non-evaluable findings. We found 26 studies (including 2298 patients) that allowed us to calculate both 2×2 tables and 3×2 tables. Using a bivariate random effects model, we compared the 2×2 table with the 3×2 table, and found significant differences for pooled sensitivity (98.2 (95% confidence interval 96.7 to 99.1) v 92.7 (88.5 to 95.3)), area under the curve (0.99 (0.98 to 1.00) v 0.93 (0.91 to 0.95)), positive likelihood ratio (9.1 (6.2 to 13.3) v 4.4 (3.3 to 6.0)), and negative likelihood ratio (0.02 (0.01 to 0.04) v 0.09 (0.06 to 0.15); (P<0.05)).Conclusion Parameters for diagnostic performance significantly decrease if non-evaluable results are included by a 3×2 table for analysis (intention to diagnose approach). This approach provides a more realistic picture of the clinical potential of diagnostic tests.
IntroductionClinical decisions in medicine are largely made on the basis of information gained from diagnostic testing. Against the background of more than 15 years of development and experience in evidence based medicine 1 and in times of comparative effectiveness research, 2 new diagnostic techniques have to be critically assessed and proven to be effective before they can be used on a wide scale. Diagnostic accuracy studies comparing an index test with a reference or gold standard and meta-analyses combining the results of many individual studies to explore a test's diagnostic potential are an important and basic step in the overall evaluation process of the validity of a new diagnostic test. 3 4 However, previous studies have shown that methodological deficits could affect the estimated diagnostic accuracy of a test.
5-7In non-invasive coronary imaging, technical innovations such as dual source 8 and 320 row computed tomography (CT) 9 have improved spatial and temporal resolution while reducing radiation. As a result of these developments, CT has evolved into the primary modality for non-invasively evaluating native coronary arteries over the past 10 years.10 11 Cardiac CT examinations performed on newer generation scanners ...