Pulmonary/original research
Outcomes and Radiation Exposure of Emergency Department Patients With Chest Pain and Shortness of Breath and Ultralow Pretest Probability: A Multicenter Study

https://doi.org/10.1016/j.annemergmed.2013.09.009Get rights and content

Study objective

Excessive radiation exposure remains a concern for patients with symptoms suggesting acute coronary syndrome and pulmonary embolism but must be judged in the perspective of pretest probability and outcomes. We quantify and qualify the pretest probability, outcomes, and radiation exposure of adults with both chest pain and dyspnea.

Methods

This was a prospective, 4-center, outcomes study. Patients were adults with dyspnea and chest pain, nondiagnostic ECGs, and no obvious diagnosis. Pretest probability for both acute coronary syndrome and pulmonary embolism was assessed with a validated method; ultralow risk was defined as pretest probability less than 2.5% for both acute coronary syndrome and pulmonary embolism. Patients were followed for diagnosis and total medical radiation exposure for 90 days.

Results

Eight hundred forty patients had complete data; 23 (3%) had acute coronary syndrome and 15 (2%) had pulmonary embolism. The cohort received an average of 4.9 mSv radiation to the chest, 48% from computed tomography pulmonary angiography. The pretest probability estimates for acute coronary syndrome and pulmonary embolism were less than 2.5% in 227 patients (27%), of whom 0 of 277 (0%; 95% confidence interval 0% to 1.7%) had acute coronary syndrome or pulmonary embolism and 7 of 227 (3%) had any significant cardiopulmonary diagnosis. The estimated chest radiation exposure per patient in this ultralow-risk group was 3.5 mSv, including 26 (3%) with greater than 5 mSv radiation to the chest and no significant cardiopulmonary diagnosis.

Conclusion

One quarter of patients with chest pain and dyspnea had ultralow risk and no acute coronary syndrome or pulmonary embolism but were exposed to an average of 3.5 mSv radiation to the chest. These data can be used in a clinical guideline to reduce radiation exposure.

Introduction

Because acute coronary syndrome and pulmonary embolism can both kill rapidly, emergency physicians frequently include them simultaneously on their differential diagnosis list for patients with symptoms referable to the chest. A large prospective study of 7,940 patients evaluated for pulmonary embolism found that 71% of them received a 12-lead ECG and 69% had at least 1 serum troponin measurement.1 Excluding acute coronary syndrome and pulmonary embolism often requires testing that imparts significant doses of ionizing radiation and intravenous iodinated contrast material in patients who have no significant disease process.2, 3, 4

Editor's Capsule Summary

What is already known on this topic

Use of imaging to rule out pulmonary embolism and acute coronary syndrome has increased during the past decade.

What question this study addressed

Estimates of radiation dose received by patients at less than 2.5% risk of pulmonary embolism or acute coronary syndrome and how often these patients receive a diagnosis of pulmonary embolism or acute coronary syndrome.

What this study adds to our knowledge

In a prospective cohort study of 840 patients, one quarter had less than 2.5% risk of pulmonary embolism and acute coronary syndrome and none had the diagnosis, but the average patient received an estimated 3.5 mSv of radiation.

How this is relevant to clinical practice

This study suggests that patients at less than 2.5% risk of pulmonary embolism or acute coronary syndrome may be able to safely forgo imaging, thereby reducing radiation exposure by 3.5 mSv. Whether this has long-term benefit to patients remains to be determined.

Exposure to radiation and intravenous contrast can have negative health consequences.5, 6, 7, 8 The potential adverse health effects of radiation exposure have generated attention from national agencies, including calls for policies to reduce medical imaging.9, 10 Several studies have found that physicians underuse pulmonary embolism diagnostic pathways that could reduce radiation exposure.11 However, to our knowledge, no study has prospectively measured radiation exposure to patients in the emergency care setting for those with chest pain or dyspnea. Moreover, no study has provided data to assess what diagnostic knowledge is gained per unit of radiation exposure.

We studied patient cumulative exposure to radiation from imaging examinations conducted to evaluate for acute coronary syndrome and pulmonary embolism for 90 days after a visit to the emergency department (ED) for chest pain and dyspnea. We focus on a group that we categorize as ultralow risk because these patients are least likely to benefit from radiation exposure. Criteria have been proposed to exclude either acute coronary syndrome or pulmonary embolism without need for extensive diagnostic testing, but to our knowledge no study has measured the potential effect on radiation exposure and outcomes of simultaneously applying criteria to rule out both acute coronary syndrome and pulmonary embolism.12, 13, 14 The main outcome measurements were the clinical diagnoses of patients with chest pain and dyspnea, total radiation exposure from medical imaging, and the potential radiation and cost savings, as well as missed diagnoses that would occur if no cardiopulmonary imaging were performed in ultralow-risk patients, where ultralow risk is defined as a pretest probability below 2.5% for both acute coronary syndrome and pulmonary embolism.15, 16, 17

Section snippets

Study Design

Data were collected in 3 academic EDs (Carolinas Medical Center Main Hospital, Charlotte, NC; Beth Isreal Deaconess Medical Center, Boston, MA; and the University of Mississippi Medical Center, Jackson, MS) and 1 community hospital (Forsyth Hospital, Winston Salem, NC). The clinical trials identifier NCT01059500 was posted January 28, 2010, and the study was conducted with an investigational device exemption from the Food and Drug Administration (IDE#125834).

Selection of Participants

Under partial waiver of

Results

We enrolled 851 patients with the clinical features shown in Table 1. Women composed 38% of the sample, half were black, and 40% were white. Fifty-one enrolled patients (6%) identified themselves as being of Hispanic ethnicity. Of relevance to risk of radiation exposure, 130 patients (15%) were women younger than 40 years. Six hundred eighty-four patients (80%) had 1 or more risk factors for coronary artery disease and 633 (74%) had 1 or more risk factors for venous thromboembolism. The mean

Limitations

Limitations to the work include the lack of a precise method to measure effective radiation dose to the patient and multiple sources of variation in the threshold for ordering diagnostic testing. We recognized that external factors (eg, energy imparted from the scanner), as well as patient factors (eg, body size), affect the actual organ dose of radiation.3, 5, 28, 29 In 2009, when this study began, we believed the best method to assess estimated radiation dose from CT scanning was from the

Discussion

We believe this to be the first study to report outcomes of patients with both chest pain and dyspnea. The data have implications on the expected list of diagnoses, radiation exposure, and the potential for pretest probability assessment to improve care for patients with these symptoms.

Table 2 provides novel data about the empiric differential diagnosis list that should be considered for adults with undifferentiated chest pain accompanied by dyspnea. In sum, 109 patients (13%) had one of the

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    Supervising editor: Judd E. Hollander, MD

    Author contributions: JAK, AEJ, JH, and JT authors were responsible for design, analysis and interpretation of data. JAK, NIS, JH, MMH, and DH collected data. All authors contributed to the drafting of the article and revising it critically for important intellectual content; and final approval of the article submitted. JAK conceived and obtained funding for the study. All authors had full access to all of the data in the study. JAK takes responsibility for the paper as a whole

    Funding and support: By Annals policy, all authors are required to disclose any and all commercial, financial, and other relationships in any way related to the subject of this article as per ICMJE conflict of interest guidelines (see www.icmje.org). Supported by R18HS018519-01 from the Agency for Healthcare Quality and Research (AHRQ). Dr. Kline owns stock in CP Diagnostics LLC, the holding company for Pretest Consult; is a consultant to Stago Diagnostica, Genentech, Janssen, and Diiachi Sankyo; and receives funding from Ikaria, the National Institutes of Health, and AHRQ. No other authors have reported disclosures.

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