Background:
Troponin assays are an important diagnostic tool, often for the evaluation of potential acute coronary syndrome. Current guidelines recommend using the assay a maximum of twice in the initial triage period if both values are negative and there is relative clinical stability. However, additional assays are often ordered to reassure the provider. Since this is a time sensitive test and can be critical for the next steps of many patients’ care, inappropriate ordering can slow down laboratory personnel and delay results. We sought to determine the volume of third troponin orders after two previous negative results and to evaluate the circumstances surrounding significantly elevated third troponin levels after two negative values.
Methods:
Troponin utilization was reviewed for 4 stand-alone emergency departments and 4 hospitals with integrated emergency departments from a large Midwestern health system. The hospitals cover different urban and suburban populations and are staffed by different models, including teaching faculty, medical group physicians, and private practice providers. All troponin assay orders were evaluated within the health system after all sites were operating on the same electronic health record (EHR), starting in June 2014 through May 2015. Orders were to be filtered for those occurring within 24 hours of 2 previous troponin assays that results as negative (<0.04 ng/mL) and totaled for each institution. All troponin assays classified as critical (≥0.20 ng/mL) after two negative values that occurred at any location were identified for further review. These cases were examined to identify the indication for troponin order and to evaluate if there was a significant change in course, as determined by the reviewer based on new electrocardiogram (ECG) findings, unstable vital signs, surgery or procedure, or progressive symptoms associated with chest pain.
Results:
For all health system locations, there were a total of 9494 troponin assays ordered after two negative values within the preceding 24 hours, of which 9207 (97.0%) were negative and 48 (0.5%) were critical. The intensive care unit was the most frequent site for critical third troponin levels (33%), followed by the emergency department (25%), general practice units (23%), and clinical decision units (19%). Of the 48 critical value patients, 10 (21%) had ECG changes, 18 (33%) had unstable vital signs, and 4 (8%) had surgery prior to the troponin rise. Only, 4 patients (8%), representing 0.04% of the total population, had no obvious change in clinical course or did not require intensive care prior to the troponin elevation. Of those four patients, only 1 patient, 0.01% of the total, had a subsequent deterioration in clinical course or significant findings on diagnostic testing following the third troponin order.
Conclusions:
Third troponin assays, after 2 negative results, are ordered in high volumes across the health system evaluated, with the vast majority still being negative. It is extremely rare for the third value to be significantly elevated, representing only 0.5% of the population. Of those patients with a critical troponin elevation, all but 0.04% were preceded by a major clinical change that should have prompted the troponin order. Significant resources could be saved, without compromise in patient safety, if troponin assays are ordered in accordance with current clinical guidelines.