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CTPA showing PE
Image courtesy of
Medical College of Georgia

ROME—A new study suggests the YEARS algorithm may provide a simple method for ruling out pulmonary embolism (PE) and therefore reduce the need for computed tomography pulmonary angiography (CTPA).

“[The YEARS algorithm] can replace current diagnostic algorithms, which, although safe and accurate, are often not used in busy emergency departments because they are too complex,” said study investigator Tom Van der Hulle, MD, of Leiden University Medical Center in the Netherlands.

“The advantage of the YEARS algorithm over existing algorithms is a 14% reduction in the need for CTPA imaging and, with that, reduced potential for radiation-induced harm and overdiagnosis.”

Dr Van der Hulle described his team’s results with the YEARS algorithm at ESC Congress 2016 (abstract 5727).

About the algorithm

The YEARS algorithm consists of a blood test and 3 items of the original Wells rule.

Patients presenting to the emergency department can be evaluated based on:

  1. Clinical signs of deep vein thrombosis (eg, swelling, edema)
  2. Hemoptysis
  3. Whether the clinician considers PE to be “the most likely diagnosis.”

Using this information combined with results of a blood test measuring D-dimer, clinicians can either exclude PE or recommend CTPA for definitive diagnosis.

Based on the algorithm, PE can be excluded in patients who have either:

  • None of the 3 YEARS items and a D-dimer level <1000 ng/mL
  • One or more YEARS items and a D-dimer level <500 ng/mL.

Testing the algorithm

Dr Van der Hulle and his colleagues prospectively evaluated the YEARS algorithm in 3465 patients. They had a mean age of 53, and 88% were outpatients.

If patients did not have PE excluded via the algorithm, they went on to CTPA. If PE was confirmed, patients received anticoagulant therapy.

Most of the patients in whom PE was excluded (either by algorithm or CTPA) were left untreated and were followed for 3 months, although 60 patients who had PE excluded received anticoagulants anyway.

In all, 1651 patients had PE excluded with the YEARS algorithm, and 1633 of them did not receive anticoagulation.

A total of 1814 patients did not have PE excluded via the YEARS algorithm and went on to CTPA. Of these patients, 456 had PE, 42 had PE excluded via CTPA but received anticoagulation, and 1316 had PE excluded but did not receive anticoagulation.

Five patients were lost to follow-up—4 with PE excluded via the YEARS algorithm and 1 who went on to CTPA.

Patient outcomes

The primary outcome of this study was the 3-month incidence of symptomatic venous thromboembolism (VTE).

A total of 2944 patients were evaluable (because they had PE excluded, did not receive anticoagulation, and were not lost to follow-up)—1629 who had PE excluded via the YEARS algorithm and 1315 who had PE excluded via CTPA.

Symptomatic VTE occurred in 0.61% of all evaluable patients, 0.43% of patients who had PE excluded via YEARS, and 0.84% of patients who had PE excluded via CTPA.

Fatal PE occurred in 0.20% of all evaluable patients, 0.12% of patients who had PE excluded via YEARS, and 0.30% of patients who had PE excluded via CTPA.

“This is fully in line with that observed in studies using traditional, sequential algorithms such as the 2-level Wells score and a fixed cut-off level of D-dimer of 500 ng/mL,” Dr Van der Hulle said.

“Using the YEARS algorithm, CTPA was not indicated in 48% of our patients at baseline, but this would have been only 34% of patients using the traditional algorithm. This shows that the YEARS algorithm can safely exclude PE and resulted in an absolute reduction of required CTPA of 14%.”

“We expect that the YEARS algorithm can be easily implemented outside the participating study sites and that these safety and efficacy outcomes are representative of what could be expected in regular clinical settings.” end hematology article

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