Embolism Recommendations Not Followed by Many Hospitals

Pam Harrison

October 12, 2018

SAN ANTONIO — Almost no hospitals in the California Veteran's Administration system adhere to national guidelines that recommend the use of a clinical decision rule and a D-dimer test before patients with pulmonary embolism are referred for CT pulmonary angiography, new research shows.

This widespread lack of adherence puts far too many patients at risk for potential complications from CT, including radiation-induced cancer, contrast-mediated complications, and hemorrhage if patients are subsequently given anticoagulants for lesions that do not require treatment.

The clinical decision rule and D-dimer test should be used for "100% of individuals" before a CT pulmonary angiography is ordered, in accordance with international guidelines, said Nancy Hsu, MD, from the University of California, Los Angeles.

"But that number is not even close in the real-world setting," she acknowledged.

The indiscriminate use of CT pulmonary angiography only serves to expose patients to unnecessary test- and treatment-related consequences.

"The indiscriminate use of CT pulmonary angiography only serves to expose patients to unnecessary test- and treatment-related consequences," Hsu said here at CHEST 2018.

She and her colleagues conducted a survey to determine how providers in the Veteran's Administration healthcare system in California approach the diagnosis of suspected pulmonary embolism in their own hospitals.

"We sent out a web-based questionnaire querying whether they were using the clinical decision rule, the D-dimer, or both for the evaluation of suspected pulmonary embolism," Hsu explained. "We assumed that the key stakeholders would be chiefs of the pulmonary, radiology, and emergency medicine departments."

The team used geographic administrative areas, known as Veterans Integrated Service Network (VISN), to collect data so that individual hospitals were not identified, she explained.

The 120 responses available for analysis came from chiefs of their respective departments with at least 11 years of clinical experience, and the three main specialties were fairly evenly represented.

"At the level of the VISN, we found a very small minority of geographic regions containing even one hospital that adhered to the guidelines," Hsu reported.

Overall, 93% of respondents said that no clinical decision rule is required before a patient is referred for a CT pulmonary angiography at their hospitals, and 89% said that D-dimer testing is not required.

If a patient has a clot, the D-dimer test should be able to detect its breakdown products, Hsu pointed out.

Only 6.7% of respondents reported that both the clinical decision rule and D-dimer test are required at their hospitals before a patient is referred for CT pulmonary angiography, 5.8% reported that the decision rule is required, and 2.5% reported that the D-dimer is required.

There was a trend suggesting that the use of the clinical decision rule, the D-dimer test, or both before angiography might boost the yield in terms of identifying pulmonary embolism on subsequent CT pulmonary angiography, Hsu pointed out.

For example, when both the decision rule and D-dimer test were ordered to assess the probability of pulmonary embolism before angiography, the average yield for pulmonary embolism on CT angiography was estimated to be 11.9%. This dropped to 8.0% when the decision rule alone was used and to 2.5% when D-dimer alone was used. When there were no requirements, the ability to detect pulmonary embolism on CT angiography was 7.6%.

The clinical decision rule and the D-dimer ELISA test "take out the random patient who should not even be considered for CT pulmonary angiography," Hsu noted. "These decision rules and the D-dimer help eliminate patients for whom the risk for pulmonary embolism is not high."

The few diagnoses other than embolism that might be obtained with CT pulmonary angiography can usually be obtained from a chest x-ray or a noncontrast CT scan, she added.

The two pretest assessments, which differentiate low- from high-risk patients, help physicians identify the right patients for CT pulmonary angiography. In such cases, it is likely that the risk of not diagnosing pulmonary embolism outweighs the risk for complications, Hsu explained.

Considerable Debate

Inappropriate CT pulmonary angiography not only costs the healthcare system, the current CT scans obtained on pulmonary angiography are highly sensitive and can pick up nonthreatening lesions, such as isolated segmental pulmonary embolism, and whether that should be treated is a matter of considerable debate, said session cochair Robert Baeten, DMSc, an academic physician assistant in Atlanta.

"Anticoagulation, in turn, has its own substantial risks," Baeten told Medscape Medical News.

Furthermore, there was no discussion about point-of-care ultrasound, which can very readily and accurately identify the presence of vascular complications, such as deep vein thrombosis (DVT).

"Using ultrasound and a simple 2-point compression test, emergency physicians can look for femoral DVT. If there is no DVT there, that study in itself has a 95% correlation with a full vascular study done by a formal radiology technician, and that could add to your clinical decision-making," Baeten said.

Hsu and Baeten have disclosed no relevant financial relationships.

CHEST 2018: American College of Chest Physicians Annual Meeting. October 9, 2018.

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