Impact of implementation of the high-sensitivity cardiac troponin T assay in a university hospital setting.

The performance of the high-sensitivity cardiac troponin T assay (hs-cTnT) 1 has been evaluated in a multicenter study (1). Effective July 2009, we replaced the fourth-generation troponin T assay (cTnT) with the hs-cTnT assay in clinical practice. This study audits the impact of this implementation. The hs-cTnT, implemented on the cobas e 411 platform (Roche Diagnostics), fully replaced the cTnT performed on the Elecsys 2010 analyzer [cutoff, 30 pg/mL— based on actual assay performance (10% CV concentration)]. We obtained a detection limit of 5 pg/mL, a 99th percentile of 15 pg/mL, limited comparability with the cTnT at concentrations Ͻ100 pg/mL (on average, a 30-pg/mL cTnT concentration yielded a value of approximately 65 pg/mL with the hs-cTnT) and mean CVs of 9.1% for the cTnT (at 39 pg/mL) and 8.5% for the hs-cTnT (at 17 pg/mL). We retrieved hs-cTnT results for the first 3 months after implementa-and cTnT results for the same period 1 year previously. Results were dichotomized as positive or negative with respect to cutoffs. Among troponin-positive patients with at least 2 results during their examination , we divided marker-release curves on the basis of typical or atypical kinetics. We defined as " typical " an increasing or decreasing pattern showing a troponin change between 2 consecutive samples exceeding ϩ46% for increasing troponin results and Ϫ32% for decreasing results. Otherwise, the troponin pattern was considered " atypical. " For definition of these percentage changes, we referred to the short-term biological variation for tro-ponin I (2). We are aware, however, that the 2 cardiac troponins may have different biological kinetics in blood, so their biological variation may be different. In the evaluated period, 2287 hs-cTnT tests were performed during 1371 examinations of 1137 patients. Correspondingly, 2170 cTnT tests were performed during 1409 examinations of 1205 patients. After hs-cTnT implementation , a 5.4% increase in the hospital-wide test volume was recorded , despite a slight decrease in the number of admitted patients and examinations. The mean (SD) number of troponin tests per examination was 1.54 (1.0) before and 1.67 (1.1) after hs-cTnT implementation (P Ͻ 0.0001), with a single test ordered in 67.5% and 60.2% of examinations, respectively. The distribution of troponin orders and positive-test rates in different wards is shown in Table 1. A positive result was found in 31.7% of cTnT tests and in 58.7% of hs-cTnT tests (relative difference , ϩ85%), corresponding to 25.3% and 51.6% positive examinations …