Cardiac Biomarker Testing Overused in ER
Cardiac biomarker testing in the emergency department (ED) is common even among those without symptoms suggestive of acute coronary syndrome (ACS), which should drive such testing, according to a study published online Nov. 17 in JAMA Internal Medicine. The researchers say that extrapolating their findings to all ED visits nationally shows that over a two-year […]
Cardiac biomarker testing in the emergency department (ED) is common even among those without symptoms suggestive of acute coronary syndrome (ACS), which should drive such testing, according to a study published online Nov. 17 in JAMA Internal Medicine. The researchers say that extrapolating their findings to all ED visits nationally shows that over a two-year period, there could have been 8.5 million instances of inappropriate testing, a pattern they define as “concerning.” Cardiac biomarker testing is not routinely indicated in the emergency department for all chest pain patients because of low utility and potential downstream consequences from false positive results. However, with the emergence of increasingly sensitive assays, testing for cardiac biomarkers is seen as a powerful tool to rapidly detect myocardial necrosis, a hallmark of ACS. The researchers analyzed retrospective data from the 2009 and 2010 National Hospital Ambulatory Medical Care Survey, a probability sample of ED visits in the United States. Of the 44,448 visits analyzed, cardiac biomarkers were tested in 16.9 percent of visits, representing 28.6 million visits nationally over a two-year period. In patients lacking ACS-related symptoms, biomarker testing occurred in 8.2 percent of visits, almost one-third of all visits with biomarker testing. The researchers estimate that up to 18.3 million visits involved testing among individuals “in the absence of any clinical suspicion of ACS.” Even among individuals subsequently hospitalized for any cause, including noncardiac diagnoses, cardiac biomarkers were tested in 47 percent of all visits, with more than one-third (35.4 percent) of these patients lacking ACS-related symptoms. The researchers note that independent of ACS symptoms, the strongest predictor of cardiac biomarker testing among all ED visits was the number of other tests or services performed. The higher the total number of tests performed, the higher the chances cardiac biomarker testing was also performed. “The high rates of testing in a population without suspicion of ACS are particularly concerning in the context of the impending adoption of highly sensitive cardiac biomarker assays in the United States, which yield more false-positive test results,” write the co-authors Anil Makam, M.D., and Oanh K. Nguyen, M.D., both from UT Southwestern Medical Center, Dallas. Makam and Nguyen argue that if there was a 2 percent ACS prevalence (“likely an overestimate,” they say) among the 8.5 million visits tested with no ACS symptoms and assuming that biomarker testing characteristics are equivalent to the highly sensitive troponin T assay (95 percent sensitivity and 80 percent specificity), “1.7 million individuals would have a false-positive biomarker test result (e.g., an elevated biomarker test result in the absence of confirmed ACS). In other words, even this highly sensitive biomarker test would have only an 8.8 percent positive predictive value in this low-risk population.” Takeaway: Researchers are in the early stages of quantifying potentially costly and harmful downstream effects of inappropriate cardiac biomarker testing among patients not presenting to the emergency department with clinical symptoms of ACS. Experts are concerned this pattern may be exacerbated by increasing usage of highly sensitive cardiac biomarker tests that come with higher rates of false positive tests.