Guideline Helps Spot Pulmonary Embolism in Cancer Patients

By David Douglas

August 19, 2019

NEW YORK (Reuters Health) - Using the American College of Physicians (ACP) guideline to evaluate cancer patients presenting to the emergency department who may have pulmonary embolism (PE) can help curtail the need for procedures such as CT pulmonary angiography (CTPA), a retrospective study suggests.

As Dr. Carol C. Wu told Reuters Health by email, employing the ACP guideline "for evaluation of suspected pulmonary embolism, based on established clinical decision rules and plasma D-dimer levels, works well in cancer patients."

"By following the guidelines," she added, "we can potentially reduce unnecessary PE protocol CTs or laboratory studies in our patients."

Timely and accurate detection of PE is of high clinical significance, and CTPA is the imaging study of choice for diagnosis, Dr. Wu of The University of Texas MD Anderson Cancer Center, in Houston, and colleagues note in the Journal of the American College of Radiology, online July 31.

However, a number of organizations have endorsed the avoidance of CTPA in ED patients with low-pretest probability of PE. The ACP recommends using a validated clinical prediction tool such as Wells scores and PE rule-out criteria (PERC) in conjunction with D-dimer levels to determine the necessity of CTPA.

The researchers studied data on 380 cancer patients who underwent CTPA over a three-month period. Each patient's diagnostic workup was assessed for its adherence to the ACP guideline, as determined by clinical risk stratification and age-adjusted D-dimer level and the degree to which these factors were associated with PE.

Only about half (56%) underwent CTPA in accordance with the ACP guideline. Meanwhile, 21% underwent "unnecessary CTPA despite having a D-dimer level below the age-adjusted cutoff or a low risk of PE and meeting all PERC," the team reports. Only one of the latter group had a PE.

Fifty-seven patients underwent "unnecessary" D-dimer evaluation, and 71 patients with negative D-dimer test results underwent nonindicated CTPA.

Altogether, say the researchers, "almost half the study cohort underwent unnecessary diagnostic testing that could have been avoided if the ACP guidelines were followed exactly."

PEs were found in six of 108 (6%) of low-risk patients, 22 of 219 (10%) of intermediate-risk patients, and 13 of 53 (25%) high-risk patients. Thus, the guideline had a negative predictive value of 99% and a sensitivity of 97%.

A cancer diagnosis alone does not obligate a patient to undergo CTPA, the researchers conclude, and observing appropriate criteria "may reduce the unnecessary use of CTPA . . . thereby not only decreasing radiation exposure among patients already likely to undergo multiple scans for life but also significantly decreasing the financial burden of their care."

Cardiologist Dr. Thomas M. Tu of Baptist Health Louisville, in Kentucky, told Reuters Health by email, "This study confirms the utility of widely accepted clinical prediction tools and D-dimer in screening cancer patients who might or might not benefit from more-advanced imaging."

Dr. Tu, who has conducted research into treatment of PE but was not involved in the new work, added, "Of course, individual physician judgment remains paramount, but this study could reduce patient exposure to low-benefit testing."


J Am Coll Radiol 2019.