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Ruling out pulmonary embolism with a simple bedside protocol

May 16, 2007

Although clots in the lung (pulmonary embolism or PE) are the second-leading cause of sudden death in the United States, blood tests and ultrafast CT scanning to detect PE are being used on so many patients that over 90% of these tests are negative. In a paper to be presented at the 2007 Society for Academic Emergency Medicine (SAEM) Annual Meeting, Jeff Kline, MD, Carolinas Medical Center, Charlotte, NC, will show that the use of simple clinical criteria can eliminate the risk and expense of these unnecessary tests.

The Pulmonary Embolism Rule-out Criteria, or the PERC rule, functions as a way to rule out clots in the lung. The blood test, called D-Dimer, has a very low specificity for PE, leading to many false positives. The CT scan costs $2500, has the potential for kidney damage in 1 in 12 patients, and has a heavy radiation dose that increases lifetime risk of cancer. Yet, doctors are ordering these tests for 2-3% of all Emergency Department patients or 3.5 million cases per year. According to the author, the fear of medical malpractice has led to a culture of doing tests rather than using the data available through clinical evaluation.

The study looked at an 8,138 patient random sample from 13 hospitals. By using a Web-based real-time data collection method and an extremely rigorous study design, it was able to capture the doctor's beliefs at the time of treatment, prior to the time that results were available. Importantly, the study design captured the physicians "gestalt" or gut instinct of how likely they thought PE was on their list. The results showed that fully two thirds of all testing is done in patients where the physician believed that the probability of PE was less than 15%.

In the best case, this study could reduce testing for PE by approximately 20-25%. More importantly, this is a first step toward a culture change of using intelligent clinical criteria instead of expensive technology to rule out life-threatening disease. According to Dr. Kline, "I interpret our data as a manifestation of the erosion of the physician-patient relationship. Physicians now believe more than ever that every patient with any hint of a life-threatening illness should have the most expensive, most technological 'standard-of-care' diagnostic test ordered to rule out that illness. This multicenter collaborative project shows that we can use a careful history and physical examination to achieve the same degree of certainty without the cost and side effects of diagnostic testing. Patients do not want a technician to check off tests on an order sheet while the physician hurries off to see the next patient. The ability to document 'PERC rule negative' on the chart will provide physicians with the scientific and medicolegal backstop they need to justify not ordering a test on every patient with any hint of PE in their history or physical examination."

The presentation is entitled "Prospective, Multicenter Validation of the Pulmonary Embolism Rule-Out Criteria" by Jeff Kline, MD, of the Carolinas Medical Center. This paper will be presented at the 2007 SAEM Annual Meeting, May 16-19, 2007, Chicago, IL on Wednesday, May 16th, in the Plenary Session beginning at 1:00 PM in Sheraton 4 & 5 of the Sheraton Chicago Hotel & Towers. Abstracts of the papers presented are published in Volume 14, Issue 5S, the May 2007 supplement of the official journal of the SAEM, Academic Emergency Medicine.

Elsevier Health Sciences