September 17, 2017
2 min read

Blood clot risk increases early after hemorrhagic fever onset

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The risk for venous thromboembolism significantly increases soon after the onset of hemorrhagic fever with renal syndrome, according to researchers.

The same is true for two morbidities related to venous thromboembolism (VTE) — deep vein thrombosis and pulmonary embolism — they wrote in Clinical Infectious Diseases.

“We show a significant but transient association between venous thromboembolism and hemorrhagic fever with renal syndrome (HFRS),” researcher Anne-Marie Connolly-Andersen, PhD, of the department of clinical microbiology’s unit of infectious diseases at Umea University in Sweden, and colleagues wrote.

They cited previous research indicating that thromboprophylaxis in at-risk patients decreases VTE.

“Our study raises the question of whether some patients with HFRS, and possibly other viral hemorrhagic fevers, could potentially benefit from similar thromboprophylaxis in the short-term period,” they added.

HFRS is caused by hantaviruses, which are transmitted from infected rodents or from their urine, feces or saliva. It has been a notifiable disease in Sweden since 1997.

In their study, Connolly-Andersen and colleagues assessed records from 7,244 patients with reported HFRS in the Scandinavian nation between 1997 and 2014. Of those patients, 146 had a first VTE. Seventy-four patients had deep vein thrombosis and 78 had pulmonary embolism.

Overall, the greatest risk for VTE came in the first 2 weeks after HFRS onset (IRR = 64.3; 95% CI, 36.3-114). The risk sharply decreased afterward and was much lower by weeks 27 to 52 after HFRS onset (IRR = 1.6; 95% CI, 0.6-3.9).

The same held true for deep vein thrombosis for which the risk was highest in weeks 1 and 2 (IRR = 45.9; 95% CI, 18-117.1) and lowest at weeks 27 to 52 (IRR = 3.2; 95% CI, 1.3-8.1).

The researchers did not have data on pulmonary embolism in the latest set of weeks, but the trend continued with the greatest risk in the first 2 weeks (IRR = 76.8; 95% CI, 37.1-159) and the lowest risk in weeks 13 to 26 (IRR = 1.2; 95% CI, 0.2-8.6).

Women had a significantly higher risk for all three morbidities compared with men in the first 4 weeks after HFRS onset (IRR = 61.1; 95% CI, 31.3-119.4 vs. IRR = 29.7; 95% CI, 13.3-66.5 for venous thromboembolism; IRR = 60.3; 95% CI, 23.3-155.8 vs. IRR = 7.9; 95% CI, 1.1-59 for deep vein thrombosis; and IRR = 71.7; 95% CI, 28.3-181.4 vs. IRR = 48.5; 95% CI, 19.5-120.8 for pulmonary embolism). – by Joe Green

Disclosure: The researchers report no relevant financial disclosures.