Cardiac biomarkers unnecessarily ordered in emergency departments

1. Based on data from a nationally representative sampling of emergency department (ED) visits, almost one in ten patients had cardiac biomarkers checked even when they had no symptoms suggestive of an acute coronary syndrome (ACS).

2. Amongst those patients later admitted to the hospital from the ED, almost one-half had their cardiac biomarkers checked, but one-third of these patients did not exhibit any ACS symptoms.

Evidence Rating Level: 2 (Good)           

Study Rundown: Acute coronary syndrome (ACS), defined as myocardial damage as a result of plaque rupture or similar coronary flow obstruction, is one of the leading causes of death in the US. As a result, testing for this has become especially important. Emergency departments frequently use cardiac biomarkers to diagnose ACS. However they are often used in low-probability situations or low-risk populations. This can increase the rate of false-positives, unnecessary testing, and hospitalizations. This study, which examined a sample of emergency department (ED) visits by adults over two years, sought to determine rates of cardiac biomarker testing based on patient characteristics. The results showed that almost one in ten patients who had no symptoms suggesting ACS still had cardiac biomarkers checked upon presentation to the ED. In addition, almost one-half of the patients who were admitted to the hospital had their cardiac biomarkers checked initially, even though one-third of these patients did not exhibit any ACS symptoms.

A major strength of the study is the categories of symptoms exhibited by patients – typical chest pain, atypical ACS symptoms, and no ACS symptoms. The investigators kept the category of “atypical ACS symptoms” broad, which means that the “no ACS symptoms” category of patients truly did not require any cardiac biomarker tests. This means that the results of the study are relatively conservative insofar as characterizing the unnecessary ordering of cardiac biomarkers. A weakness of the study is the retrospective design, which makes it difficult to identify causality, and also adds hindsight bias.

Click to read the study, published today in JAMA Internal Medicine

Relevant Reading: Undetectable high-sensitivity cardiac troponin T level in the Emergency Department and risk of myocardial infarction

In-Depth [retrospective cohort]: The data for the study was obtained from the 2009-2010 National Hospital Ambulatory Medical Care Survey (NHAMCS), a nationally representative sample of ED visits. In the study, 44,448 visits were included, of which 8.8% had chest pain, 30.1% had potential atypical ACS symptoms, and 61.6% had no ACS symptoms. Amongst all patients presenting with non-ACS symptoms, 8.2% still had cardiac biomarkers checked. In regards to disposition, of those patients admitted to the hospital, 47% had their biomarkers checked in the ED. However, of those patients who had biomarkers checked and were admitted, 35.4% had not reported any symptoms suggestive of ACS. The strongest predictor of cardiac biomarkers testing was the number of other tests and services the patients received. The adjusted probability of getting cardiac biomarkers tested if 0-5, 6-10, and more than 10 other tests and services were performed were 6.3%, 34.3%, and 62.3%, respectively.

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Image: PD

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