Accounting for Age Rules Out Pulmonary Embolism in Elderly Patients

Considering a patient’s age in an abnormal pulmonary embolism (PE) test result can lead to fewer misdiagnoses in healthy individuals, according to a study published in the March 19, 2014, issue of JAMA.

For the ADJUST-PE study, researchers from Geneva University Hospital in Switzerland examined 3,346 elderly patients with suspected PE from 19 centers in Belgium, France, the Netherlands, and Switzerland between January 2010 and February 2013. The patients underwent testing on a revised and simplified Geneva score or the 2-level Wells score for PE, sensitive D-dimer measurement, and computed tomography pulmonary angiography (CTPA).

According to the study authors, physicians can diagnose PE by measuring levels of D-dimer, a breakdown product of a blood clot. However, D-dimer levels have been shown to increase with age, which limits the PE test’s clinical usefulness in older patients.

Thus, the researchers redefined normal and abnormal values for a new test formula to more accurately diagnose elderly patients with PE. To do so, they multiplied the patient’s age by 10 for those aged 50 years or older, which allowed PE to be excluded from potential diagnoses.

Patients with a D-dimer measurement between the standard fixed cutoff of 500 µg/L and the new cutoff based on the age-adjusted formula did not undergo CTPA and were left untreated. After 3 months, they underwent a formal follow-up.

Among suspected PE patients, the actual disease prevalence was 19%. Of the 2,898 patients with a non-high or unlikely clinical probability of PE, 817 patients (28.2%) had D-dimer levels that were lower than the standard test outcomes, while 337 (11.6%) patients’ rates fell somewhere between the conventional and age-adjusted cutoffs.

The researchers also examined 766 patients aged 75 years or older, 673 of whom were categorized in the non-high clinical probability in the standard PE test. Using the conventional D-dimer testing method, 43 (6.4%) patients were excluded. But under the new formula, 200 (29.7%) patients were excluded without any additional false-negative findings.

“The combination of pretest clinical probability assessment with age-adjusted D-dimer cutoff was associated with a larger number of patients in whom PE could be considered ruled out with a low likelihood of subsequent clinical venous thromboembolism,” the authors concluded.