Reporting age-adjusted D-dimer cut-off values reduces radiology overuse in emergency department patients with suspected deep venous thrombosis

Introduction: Venous thromboembolism (VTE) is a leading cause of death, associated with substantial morbidity in the absence of treatment. Our aim was, first, to compare the diagnostic performance of D-dimer for the diagnosis of VTE in the emergency department (ED), when reporting conventional cut-off point versus when additionally reporting age-adjusted values. Second, we explored the ordering pattern of Doppler ultrasound (US) and computerized tomographic pulmonary angiogram (CTPA), before and after reporting of the aforementioned age-adjusted cut-off value.

Materials and methods: We conducted a cross-sectional study to compare the diagnostic performance of D-dimer as a screening for VTE when reporting the conventional cut-off value versus when additionally including the age-adjusted metrics, and a quasi-experimental study to explore the ordering of Doppler US and CTPA before the age-specific metrics were shared in the report in ED patients between 50 and 100 years-old with D-dimer ordering.

Results: The cross-sectional study included 392 patients, 25 with VTE. The specificity using an age-adjusted cut-off value was significantly higher (0.51) compared to a single absolute cut-off (0.42), and the negative likelihood ratio was lower as well (0.08 vs. 0.19), but again not statistically significant. In the quasi-experimental study, there was a decrease in the rate of use of both CTPA and Doppler US (P < 0.05).

Conclusion: The intervention improved the use of the D-dimer result in the ED and helped improve the request for imaging tests.