Laboratory virus test positivity is not associated with increased venous thromboembolism risk among patients presenting with acute respiratory illnesses to U.S. emergency departments.

BACKGROUND: An ongoing concern in emergency departments is whether the risk of developing venous thromboembolism (VTE) is increased among acute respiratory illness (ARI) patients with positive virus tests. METHODS: This serial cross-sectional study uses data collected prospectively by the U.S. CDC-sponsored Respiratory Virus Laboratory Emergency Department Network Surveillance (RESP-LENS) program from August 2021 to September 2024. Standardized protocols were used to rigorously collect clinical information from consecutive patients of all ages who presented to 91 hospitals with acute respiratory illnesses (ARIs). Hazard ratios with 95% confidence intervals were estimated using time-varying Cox proportional hazards models with robust standard errors. FINDINGS: 1,106,634 unique patients presented with1,391,306 encounters during the study period, and 66% of had laboratory virus testing: 18% were positive for SARS CoV-2, 3% for RSV, 7% for influenza and 2% for multiple viruses. 16,123 patients were diagnosed with VTE within 30 days for a prevalence rate of 1.46% (95%CI 1.43%-1.48%). Compared to patients with negative test results and after adjusting for comorbid conditions, virus test positivity was not significantly associated with VTE among discharged ED patients, inpatients or the subset transferred to the ICU. Similarly adjusted models showed that VTE was significantly associated with increased adjusted hazard of in-hospital mortality among ED patients (HR[95%CI]: 7 [3.7-13]), and inpatients (1.6 [1.3-2]). respectively. Virus test positivity did not modify associations between VTE and in-hospital mortality (interaction p > 0.25). INTERPRETATION: In the U.S., laboratory-confirmed virus infection was not associated with increased risk of short-term VTE diagnosis or death among patients seeking emergency care.