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Admission Laboratory Values May Improve Prognostication for Hospitalized COVID-19 Patients

Key findings

  • This two-center retrospective study involved 138 patients hospitalized with COVID-19 who underwent ultrasonography or computed tomography pulmonary angiography for suspected venous thromboembolism (VTE)
  • The incidence of VTE was 32% despite thrombosis prophylaxis
  • The median time from COVID-19 symptom onset to the diagnosis of VTE was 13.5 days
  • There was a trend for elevated admission C-reactive protein to be associated with increased risk of death (P=0.06)

It's become clear the risk of venous thromboembolism (VTE) is increased in hospitalized patients with COVID-19. It's not yet established, though, how the laboratory tests ordinarily used to predict thrombotic complications, such as elevated D-dimer, relate to the development of VTE in this population.

Vikas Thondapu, MD, PhD, research fellow in the Cardiovascular Imaging Research Center at Massachusetts General Hospital, and Sandeep Hedgire, MD, assistant clinical director of Cardiovascular Imaging and director of Vascular Imaging at Mass General, and colleagues recently conducted a retrospective study of this issue that had considerably longer follow-up than the studies to date. In the Journal of Vascular Surgery: Venous and Lymphatic Disorders, they say elevated D-dimer at admission was independently associated with increased risk of intubation and death in COVID-19.

Study Cohort

The two-center retrospective study involved 138 adults who were hospitalized with COVID-19 between March 13 and May 18, 2020. All underwent ultrasonography or computed tomography pulmonary angiography because of suspected VTE. 126 patients received pharmacologic thrombosis prophylaxis before imaging; the other 12 had a contraindication.

Patients were followed until death, discharge or August 7, 2020, whichever occurred first, for a median follow-up period of 39.5 days (IQR, 15.3–100 days).

Primary Outcome

The incidence of VTE was defined as the composite of deep vein thrombosis (DVT), superficial venous thrombosis (SVT) and pulmonary embolism (PE):

  • Despite prophylaxis, 44 patients (32%) had evidence of VTE
  • Of those, 61% had DVT alone, 23% had SVT alone, 14% had PE alone and 2% had DVT plus PE
  • The median time from COVID-19 symptom onset to diagnosis of VTE was 13.5 days (IQR, 7–25 days)

Multivariable Analysis

  • No laboratory test result predicted incidence of VTE; male sex was the only prognostic factor (OR, 2.37; 95% CI, 1.01–5.56; P=0.048)
  • Elevated admission D-dimer was associated with increased risk of intubation (HR, 1.01; 95% CI, 1.001–1.02; P=0.04)
  • In addition to increasing age and active malignancy, independent predictors of death were disseminated intravascular coagulation (HR, 4.81; 95% CI, 1.76–13.1; P=0.002) and elevated admission D-dimer (HR, 1.016; 95% CI, 1.003–1.03; P=0.02)
  • There was a trend for elevated admission C-reactive protein to be associated with increased risk of death (P=0.06)
  • VTE itself was not associated with an increased length of stay or death

Implications for Frontline Clinicians

A low threshold of clinical suspicion for VTE seems warranted in patients with COVID-19, especially in the second and third weeks after COVID-19 symptom onset.

If confirmed by larger prospective studies, these findings suggest a role for using laboratory test results at admission to evaluate the risk of adverse outcomes for patients with COVID-19. Although elevated admission D-dimer was not associated with venous thrombosis itself, it seems to reflect greater overall severity of COVID-19.

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Prothrombin fragment 1.2, a serologic marker of coagulation activation, identified which patients hospitalized for COVID-19 would develop thrombosis, and it was more discriminant than D-dimer.

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When deep vein thrombosis is suspected in COVID-19 patients, Massachusetts General Hospital procedures for ordering and performing ultrasound have decreased the number of scans and reduced the sonographer's exposure time.