Canadian researchers have discovered an approach to interpret blood test results in patients examined for pulmonary embolism (PE), a condition of blood-clotting in the lungs.

The approach applies to D-dimer blood tests used to rule out the presence of blood clot.

The study, led by Hamilton Health Sciences, found that a higher D-dimer level than average could be considered a negative result if the doctor has evaluated the patient to have a low probability of pulmonary embolism.

The approach could reduce the need for CT scans, enabling patients’ to pass quickly through the emergency department.

McMaster University professor of medicine and Hamilton Health Sciences thrombosis specialist Clive Kearon said: “The primary goal of diagnostic testing for pulmonary embolism is to identify which patients should be treated with anticoagulant agents and which should not.

“When a physician is concerned that pulmonary embolism may be present, chest imaging with CT pulmonary angiography is usually done in half of these patients. We wanted to find a way to reduce the number of CT scans that need to be done.”

The study evaluated 2,017 patients; 7% had PE on initial diagnostic testing. The average age of those enrolled was 52 years, with female patients forming 66% of the total number of patients studied.

An emergency department physician identified 1, 325 patients as having a low or moderate probability of having a PE. These patients had negative D-dimer results, with none indicating venous thromboembolism during follow-up.

Canadian Institutes of Health Research provided funds for the study, endorsed by the Canadian Venous Thromboembolism Clinical Trials and Outcomes Research.

The Ontario Clinical Oncology Group of McMaster and Hamilton Health Sciences coordinated the study.