Mark H. Ebell, MD, MS Linda L. White, RN, MPH David Weismantel, MD East Lansing, Michigan Submitted, revised, May 26, 2000. From the Department of Family Practice, Michigan State University. Reprint requests should be addressed to Mark H. Ebell, MD, MS, Department of Family Practice, Michigan State University, B101 Clinical Center, East Lansing, MI 48824-1315. E-mail: ebell@msu.edu.
References
Recommendations for future research
To facilitate future meta-analyses, we recommend the following parameters for the design of studies of troponin. First, studies should use larger populations and standardize their inclusion and testing criteria. We also recommend durations of follow-up of 7 days, 30 days, and 1 year. Although a longer duration is helpful in predicting the patient’s overall prognosis, shorter durations are more useful for identifying patients who can be discharged for close outpatient follow-up and noninvasive testing. Cutoffs of 0.05 ng/mL, 0.10 ng/mL, and 0.20 ng/mL for troponin T and cutoffs of 0.3 and 0.6 for troponin I should be used. Authors should report the test characteristics for several cutoffs and also for ranges of troponin, such as less than 0.05 ng/mL, 0.06 ng/mL to 0.10 ng/mL, and greater than 0.10 ng/mL. In addition, we recommend that sensitivity and specificity be reported both for the initial value on admission to the emergency department and for peak values after 12 and 24 hours. Finally, standard definitions for inclusion criteria and outcomes should be used, such as the Braunwald criteria* for unstable angina and the World Health Organization criteria for acute MI.
We also suggest that valuable information would be added if population demographics were reported in study results. Although most studies considered patient demographics carefully in determining study eligibility, they did not report those characteristics in their findings. It is not clear, for example, that the test performs similarly in younger and older patients, in men and women, or in different ethnic or racial groups.
Finally, we recommend that more studies evaluate the accuracy of troponin I in prognosis, particularly among patients with chest pain syndromes. Of the 28 studies we analyzed, only 11 measured troponin I and only 1 enrolled patients who had chest pain and a normal ECG.
Recommendations for practice
If the peak troponin T or I level measured at least 6 hours after the onset of chest pain symptoms is in the normal range and the ECG is normal, it is very unlikely that the patient will die or have a nonfatal MI in the next 30 days (1%).14 It is important to note that decisions about care should be made on the basis of the troponin value and ECG and in light of the patient’s clinical presentation and comorbidities, and that this finding is based on only 1 study, albeit a large one. The initial troponin value is not as helpful as the peak value at least 6 hours after the onset of chest pain. An abnormal troponin test in patients with unstable angina or non-Q-wave MI identifies a subset at greater risk of death; those patients should be closely monitored.
Acknowledgments
This project was supported by the Michigan Consortium for Family Practice Research, one of 3 research centers funded by the American Academy of Family Physicians. We wish to acknowledge the assistance of Dan Flewelling in the literature search and of Deb Richardson in the preparation of the manuscript.
