Measurement of cardiac troponin I in serum with a new high-sensitivity assay in a large multi-ethnic Asian cohort and the impact of gender

Background: As new high-sensitivity (hs) cardiac troponin (cTn) assays are introduced decision limits, based on the 99th percentile upper reference limit (99 percentile URL), for each method must be determined and from a sufficiently large cohort to mitigate against distortionary effects of high-end outliers. There is a paucity of studies with large multi-ethnic cohorts. Methods: We determined the 99 percentile URL in 1120 (mean age: 50.4 +/- 82 y) apparently healthy (no history of diabetes, hypertension, heart, lung, or renal disease) Asians (597 men aged 35-65 y, 523 women aged 40-65 y) in a pre-market hs-cTnI assay (Abbott Diagnostics). Results: Hs-cTnI performance was: limit of blank -0.6 ng/I, limit of detection (LoD) -1.5 ng/I; cTnI inter-assay coefficient of variation of 20% and 10% were 1.5 and 6.0 ng/I respectively. Hs-cTnI concentrations (range: 0-493 ng/I) were detectable (> assay LoD) in 92.3% of participants, and higher in men and individuals >50 y. All-subject, male, and female 99 percentile URL (90% Cl) were 25.6 (19.6-32.6), 32.7 (21.1-47.9) and 17.9 (10.7-26.3) ng/I respectively. Conclusion: This hs-cTnI assay exhibits hs performance besides gender and age differences. The all-subject 99 percentile URL values are similar to those reported from some groups but not in others. Users need to establish their own decision limits. (C) 2013 Elsevier B.V. All rights reserved.