Written by Christopher Thom
Assessing pretest probability using a modified, age-adjusted clinical decision tool (“Adjust-Unlikely”) vs YEARS reduces CT imaging in patients with suspected pulmonary embolism (PE). “Adjust-Unlikely” missed no PEs. YEARS had a larger reduction of imaging but missed a few PEs.
Why does this matter?
PE is a potentially life-threatening diagnosis. Multiple guidelines recommend that patients who are not high-risk should undergo risk stratification at the bedside and a D-dimer prior to CT imaging. ED physicians frequently overestimate patients who are “high risk” and forgo a more formal calculation of risk. The authors sought to reduce the burden of using a complex clinical decision tool (i.e. Wells) by employing an “Adjust-Unlikely” approach which made selective use of age-adjusted D-dimer.
Consider adjusting beyond your YEARS using an “adjust-unlikely” approach
This was a prospective study of 1,961 patients conducted at two Canadian emergency departments (EDs). All eligible patients being tested for suspected PE were worked up using a standard PE order set (D-dimer, renal function, CBC). If the D-dimer was ≥500 ng/mL, CT or VQ was ordered. Patients were enrolled in a consecutive series, and physicians prospectively recorded YEARS criteria before D-dimer and imaging. Diagnosis of PE was determined by diagnostic imaging performed in the ED or by medical record review at 30 days. Overall, 8% of patients were diagnosed with acute PE on CT during their index ED visit.
Authors compared two diagnostic strategies: “Adjust-Unlikely” vs. YEARS. The “Adjust-Unlikely” strategy involved using the age-adjusted D-dimer (age x 10 in patients older than 50) in cases where PE was not the most likely diagnosis. For those with PE as the most likely diagnosis, the standard D-dimer level of 500 ng/ml was used as the cutoff (Fig below). The sensitivity of YEARS for PE was 92.6% (95%CI 87-96); specificity 45%. The “Adjust-Unlikely” strategy had a sensitivity of 100% (95%CI 97.2-100); specificity 32%.
Although, it is not clear why the use of YEARS yielded a lower sensitivity than prior studies, the use of age-adjusted D-dimer in the “PE unlikely” cohort missed 0 PEs. The study was not a direct comparison of the standard use of age-adjusted D-dimer, but age-adjusted D-dimer in low to moderate risk patients has also been demonstrated as a safe approach and is supported by guidelines. Prospective implementation of “adjust-unlikely” would be a large lift, but our fingers are crossed for a future trial!
Peer reviewed by Bo Stubblefield
Editor’s note: I like this new approach. It may not reduce imaging as much as YEARS, but it looks like it will miss fewer PEs. ~Clay Smith
Comparison of YEARS and Adjust-Unlikely D-dimer Testing for Pulmonary Embolism in the Emergency Department [published online ahead of print, 2022 Nov 10]. Ann Emerg Med. 2022;S0196-0644(22)01118-0.