High-Sensitivity Cardiac Troponin T Reporting, Clinical Outcomes, and Health Care Resource Use.

Importance: Despite being recommended by clinical guidelines, substantial concerns remain regarding the use of high-sensitivity cardiac troponin assays and whether it is associated with increased resource use, myocardial infarction (MI) or myocardial injury diagnoses, and procedural rates. Objective: To characterize the association of reporting high-sensitivity cardiac troponin T (hs-cTnT) to the lowest limit of quantification vs conventional troponin reporting with clinical outcomes. Design, Setting, and Participants: This cohort study used a historically controlled baseline and follow-up design to compare clinical outcomes after changing hs-cTnT reporting to the lowest limit of quantification. All patients aged 18 years or older presenting to any public emergency department (ED) in the state of South Australia between February 1, 2020, and February 28, 2021, who had an hs-cTnT test in the 6 months before and after the change in troponin reporting practice were included. Outcomes were assessed after adjusting for patient characteristics using inverse probability treatment weighting. The data analysis was performed between May 1, 2022, and July 27, 2023. Exposure: hs-cTcnT reporting. Main Outcomes and Measures: The main outcomes were frequency of diagnosed MI, coronary angiography, percutaneous coronary intervention, and coronary artery bypass graft (CABG); hospital length of stay; and ED discharge rate as measured using time-to-event Cox regression models. The secondary outcome was the composite 12-month event rate of all-cause mortality, MI, and myocardial injury. Results: A total of 40 921 patients were included, of whom 20 206 were included in the unmasked hs-cTnT reporting group (median [IQR] age, 62.0 [46.0-77.0]; 10 120 females [50.1%]) and 20 715 were included in the conventional troponin reporting group (median [IQR] age, 63.0 [47.0-77.0] years; 10 752 males [51.9%]). Unmasked hs-cTnT reporting was associated with higher ED discharge rates (45.2% vs 39.0%; P < .001) and a shorter median hospital length of stay (7.68 [IQR, 4.32-46.80] hours vs 7.92 [IQR, 4.56-49.92] hours; P < .001). There was no difference in diagnosis of MI, coronary angiography, percutaneous coronary intervention, or coronary artery bypass graft. The composite of all-cause mortality, MI, and myocardial injury at 12 months was similar (adjusted hazard ratio, 0.95; 95% CI, 0.90-1.01; P = .09). Conclusions and Relevance: This cohort study found that unrestricted reporting of hs-cTnT results to the lowest limit of quantification was not associated with an increase in the diagnosis of MI, invasive coronary procedures, or harm at 12 months but may be associated with improved hospital resource use.