Utility of D-dimer for diagnosis of deep vein thrombosis in COVID-19 infection

Cho, Edward S.; McClelland, Paul H.; Cheng, Olivia; Kim, Yuri; Hu, James; Zenilman, Michael E.; D’Ayala, Marcus

OBJECTIVE: The objective of this study was to investigate the clinical utility of D-dimer in excluding a diagnosis of deep vein thrombosis (DVT) in patients with COVID-19 infection, potentially limiting the need for venous duplex ultrasonography (US). METHODS: We retrospectively reviewed consecutive patients admitted to our institution with confirmed COVID-19 status by PCR between March 1, 2020 and May 13, 2020 and selected those who underwent both D-dimer and venous duplex US. This cohort was divided into two groups, those with and without DVT based on duplex US. These groups were then compared to determine the value of D-dimer in establishing this diagnosis. RESULTS: A total of 1170 patients were admitted with COVID-19, of which 158 were selected as our study. Of the 158, there were 52 patients with DVT and 106 without DVT. There were no differences in gender, age, race, or ethnicity between groups. Diabetes and routine hemodialysis were less commonly seen in the group with DVT. Over 90% of patients in both groups received prophylactic anticoagulation, but the use of LMWH or subcutaneous heparin prophylaxis was not predictive of DVT. All patients had elevated acute-phase D-dimer levels using conventional criteria, and 154/158 (97.5%) had elevated levels with age-adjusted criteria (mean D-dimer 16,163 ± 5,395 ng/mL). Those with DVT had higher acute-phase D-dimer levels than those without DVT (median 13,602 [6,616-36,543 ng/mL] vs. 2,880 [1,030-9,126 ng/mL], p < 0.001). An optimal D-dimer cutoff of 6,494 ng/mL was determined to differentiate those with and without DVT (sensitivity 80.8%, specificity 68.9%, negative predictive value 88.0%). Wells DVT criteria was not found to be a significant predictor of DVT. Elevated D-dimer as defined by our optimal metric was a statistically significant predictor of DVT in both univariate and multivariable analyses when adjusting for other factors (OR 6.12, 95%CI [2.79-13.39], p <0.001). CONCLUSION: D-dimer levels are uniformly elevated in COVID-19 patients. While standard predictive criteria failed to predict DVT, our analysis showed a D-dimer of less than 6,494 ng/mL may exclude DVT, therefore potentially limiting the need for venous duplex ultrasonography.