The use of D-dimer test adjustment based on the results of the pretest probability may be a valid and safe option to reduce the need for imaging during the evaluation process for a possible pulmonary embolism (PE), according to a study published by Academic Emergency Medicine.
Researchers conducted a prospective, observational study of 1789 adult patients in 17 emergency departments in the United States from February 2014 to April 2015 who were evaluated for PE to determine whether PE could be safely ruled out in patients with a low pretest probability, using a higher than normal (standard) D-dimer threshold.
The YEARS criteria (“Does the patient have clinical signs or symptoms of [deep venous thrombosis]?” “Does the patient have hemoptysis?” “Are alternative diagnoses less likely than PE?”) were used to initially evaluate the patient before diagnostic testing.
A negative D-dimer was <500 mg/dL for YEARS (+) patients (“yes” was the answer to any of the YEARS criteria questions), whereas a negative D-dimer was <1000 mg/dL for YEARS (−) patients, as this was the standard threshold previously determined to be sufficient to rule out PE. Patients with a positive D-dimer subsequently underwent diagnostic imaging.
YEARS criteria were negative in 1235 patients (69%). A total of 554 (31%) of patients had a positive YEARS criteria, with 142 (26%) presenting with clinical signs and symptoms of deep venous thrombosis, hemoptysis, or an alternative diagnosis less likely than PE (26%, 9%, and 73%, respectively).
When the D-dimer value was adjusted on the basis of the YEARS criteria, 1204 patients would not be referred for imaging (67%; 95% CI, 65%-69%), which resulted in 6 patients being diagnosed with PE: 5 diagnosed on the basis of computed tomography pulmonary angiography at the index visit and 1 diagnosed on follow-up (0.5% [95% CI, 0.18%-1.1%], 0.4% [95% CI, 0.13%-0.96%], and 0.1% [95% CI, 0.02%-0.46%], respectively).
Of note, when adjusting the D-dimer based solely on the question, “Are alternative diagnoses less likely than PE?” Most patients would not be referred for imaging (67%; 95% CI, 65%-70%), resulting in 6 patients diagnosed with a PE: 5 diagnosed based on computed tomography pulmonary angiography at the index visit, and 1 on follow-up (0.4% [95% CI, 0.17%-1.05%], 0.4% [95% CI, 0.13%-0.94%], and 0.1% [95% CI, 0.02%-0.45%], respectively), demonstrating that the 1 alternative diagnosis question alone produces similar results to those using the YEARS approach.
Researchers concluded that the adjustment of the D-dimer threshold according to pretest probability YEARS criteria could potentially result in a 14% decrease in imaging compared with the standard approach for evaluation of a PE in low- to intermediate-risk patients. Further, the reduction in imaging would result in missing 7% of PEs compared with 2% (0.2% increase) using the standard approach. The sensitivity was slightly lower, at 93%, compared with when using the negative YEARS criteria and negative D-dimer, at 98%, but the low prevalence resulted in an almost 100% negative predictive value. Therefore, clinicians should consider using the adjusted D-dimer when evaluating patients with low and intermediate risk for PE, as this study found it to be a valid and safe method that reduces unnecessary imaging.
Kabrhel C, Van Hylckama A, Muzikanski A, et al. Multicenter evaluation of the YEARS criteria in emergency department patients evaluated for pulmonary embolism [published online March 31, 2018]. Acad Emerg Med. doi: 10.1111/acem.13417