OBJECTIVES To describe the predictive utility of the D-dimer assay among patients with the coronavirus disease 2019 syndrome for unprovoked lower extremity deep venous thrombosis .
DESIGN Prospective observational study with retrospective data analysis .
SETTING Academic medical center surgical ICU . PATIENTS Seventy-two intubated patients with critical illness from coronavirus disease 2019 .
INTERVENTIONS Therapeutic anticoagulation after imaging diagnosis of the first three deep venous thrombosis cases was confirmed; therapeutic anticoagulation as prophylaxis thereafter to all subsequent ICU admissions .
MEASUREMENTS AND MAIN RESULTS Seventy-two patients with severe coronavirus disease 2019 were screened for deep venous thrombosis after ICU admission with 102 duplex ultrasound examinations, with 12 cases (16.7 %) of lower extremity deep venous thrombosis identified . There were no differences between groups with respect to age, renal function, or biomarkers except for D-dimer (median , 12,858 ng/mL [interquartile range , 3,176-30,770 ng/mL] for lower extremity deep venous thrombosis vs 2,087 ng/mL [interquartile range , 638-3,735 ng/mL] for no evidence of deep venous thrombosis; p <0.0001). Clinical screening tools (Wells score and Dutch Primary Care Rule) had no utility . The C-statistic for D-dimer concentration was 0.874 ± 0.065 . At the model-predicted cutoff value of 3,000 ng/mL, sensitivity was 100%, specificity was 51.1%, positive predictive value was 21.8%, and negative predictive value was 100% .
CONCLUSIONS Lower extremity deep venous thrombosis is prevalent in coronavirus disease 2019 disease and can be present on ICU admission . Screening has been recommended in the context of the pro-inflammatory, hypercoagulable background milieu . D-dimer concentrations are elevated in nearly all coronavirus disease 2019 patients, and the test appears reliable for screening for lower extremity deep venous thrombosis at or above a concentration of 3,000 ng/mL (more than 13-fold above the normal range). Full anticoagulation is indicated if the diagnosis is confirmed, and therapeutic anticoagulation should be considered for prophylaxis, as all coronavirus disease 2019 patients are at increased risk.