Simple diagnostic algorithm to assess pulmonary embolism risk can help reduce rate of CTPA imaging

Patients with suspected pulmonary embolism (PE) often undergo computed tomography pulmonary angiography (CTPA) to confirm or exclude the diagnosis.

However, CTPA exposes them to radiation, the risk of contrast-induced nephropathy, and increases health care costs. Therefore ways to reduce the use of CTPA in this setting are needed.

Now, new findings presented at ESC Congress 2016, suggest a simple diagnostic algorithm can be used to rule out PE in a significant number of these patients, eliminating their need for 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," noted YEARS study investigator Tom van der Hulle, MD, from 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." Unlike other, multi-item, sequential algorithms used to assess PE risk, the YEARS clinical decision rule consists of one blood test and 3 items of the original Wells rule.

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

• clinical signs of deep vein thrombosis (e.g., swelling, edema);
• hemoptysis (coughing up blood);
• and whether the clinician considers PE to be "the most likely diagnosis".

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

The YEARS study prospectively evaluated this algorithm in 3,465 patients (mean age 53 years), 88% of whom were outpatients. Based on the algorithm, PE was excluded and CPTA was withheld in 1,651 patients who either had: no YEARS items and a D-dimer level <1000 ng/mL; or one or more YEARS items and a D-dimer level <500 ng/mL.

All other patients were referred for CTPA.

Patients in whom PE was excluded were left untreated and followed for 3 months, while those diagnosed with PE were treated with anticoagulants.

The primary outcome of the study was the 3-month incidence of symptomatic venous thromboembolism (VTE), which occurred in 0.43% of patients who had PE excluded based on the YEARS algorithm alone and 0.84% of the patients who had PE excluded based on 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," noted Dr. van der Hulle. "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 CPTA of 14%."

He added, "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."