{'fraction_non_alphanumeric': 0.03811369509043928, 'fraction_numerical': 0.010981912144702842, 'mean_word_length': 4.912213740458015, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 1, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Increasing cardiac troponin changes measured by a research high-sensitivity troponin I assay: absolute vs percentage changes and long-term outcomes in a chest pain cohort.

To the Editor:

With novel high-sensitivity cardiac troponin assays, there is great interest in determining the change needed between successive cardiac troponin measurements to inform the diagnosis of acute myocardial infarction (MI)1 (1). Recent publications have reported both short- and long-term reference change values (RCVs) in healthy populations for both high-sensitivity cardiac troponin I (hs-cTnI) and high-sensitivity cardiac troponin T (hs-cTnT); thus, the RCV perhaps could be the metric used for determining the optimal clinical change value (2, 3). The RCVs for the hs-cTnT and hs-cTnI assays, however, are markedly different, possibly because of assay characteristics, differences in the biology of the 2 isoforms, or the healthy populations studied (1). The optimal clinical change for detecting patients with acute MI might be greater than the published RCVs. Two recent studies that used ROC curve analyses suggest exactly that. Giannitsis et al. (4) determined the optimal δ to be ≥243% for hs-cTnT, whereas we identified an optimal δ of >235% on the basis of MI or death at 30 days for a research hs-cTnI assay (5). Percentages may work well when values are low but may become impractical when more substantial increases occur. The 2 studies neither reported δ in terms of absolute concentration nor defined its role in long-term risk stratification. …