Clinical comparison of 99th percentile and 10% coefficient of variation cutoff values for four commercially available troponin I assays

Abstract

Background: Measurement of troponin concentration is important for evaluating patients with suspected acute myocardial infarction or cardiac damage, with results interpreted relative to method-specific cutoff values. This study evaluates changes in sample categorization and patient management based on different test methods. Methods: Plasma specimens were tested for troponin I on 4 different instrument platforms, with chart review. Results were compared with cutoff values corresponding to the 99th percentile reference interval and the concentration having 10% coefficient of variation. Results: Significant correlations were observed among instrument platforms (R2≥0.94). However, 44% of patients were categorized differently by instrument-specific cutoff values. The use of higher sensitivity assays was associated with 47% to 106% increase in number of results exceeding both the 99th percentile and 10% CV cutoffs. Conclusions: Changing instrument platforms can cause reclassifications of patient results. Laboratories adopting new troponin measurement methods should perform clinician education regarding its interpretation and the importance of serial testing.