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Updated: Aug 5, 2026

Point-Of-Care Ultrasound Screening for Proximal Lower Extremity Deep Venous Thrombosis
Published on: February 10, 2023
Risk of venous thromboembolism in first-degree relatives of affected patients compared with general population
Sara Robin1, Alice Nau2, Eloïse Laouenan3
1Univ_Brest, Inserm UMR 1304-GETBO, CIC-P1412, Brest, France; Vascular Medicine Unit, CHU Brest, 29200, Brest, France.
Background:
Determining venous thromboembolism (VTE) risk among first-degree relatives (FDRs) of VTE patients requires effective risk assessment. We aimed to evaluate VTE risk in FDRs of index cases (ICs) compared to the general population.
Methods:
A cross-sectional family study (France, Canada) and a population-based study in the Brest district (France) were conducted. VTEs were adjudicated by an independent clinical event committee. The standardised incidence ratio (SIR), defined as observed-to-expected ratios of VTE in FDR, and 95% confidence interval (CI) were calculated using an indirect standardisation. Expected numbers of VTE were calculated from age-specific incidence rates in the reference population.
Results:
Among the 2617 FDRs of 507 ICs with VTE, 123 had VTE (annual incidence: 1.2 per 1000 person-years). Of 367,911 Brest district inhabitants, 576 had VTE (annual incidence: 1.6 per 1000 person-years). Compared with the general population, FDRs had a higher VTE risk when the ICs had unprovoked VTE (SIR 1.31, 95%CI 1.11-1.53), had VTE before 47 years (SIR 3.28, 95%CI 2.69-3.85) or when ≥2 FDRs were affected (SIR 1.51, 95%CI 1.14-1.88). The highest VTE risk in FDRs was observed when ICs had unprovoked VTE and ≥2 affected FDRs (SIR 6.36, 95%CI 5.52-7.20) or when ICs had VTE before 47 and ≥2 affected FDRs (SIR 9.93, 95%CI 7.75-12.12). Factor V Leiden and G20210 prothrombin variant status of ICs had a modest influence.
Conclusion:
FDR VTE risk is significantly higher when the IC had unprovoked VTE, before 47 years, and/or when multiple FDRs were affected, compared to the general population.
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