A pilot study to assess the feasibility of a multicenter cluster randomized trial for the management of asymptomatic persons with a thrombophilia.

There is controversy whether asymptomatic first-degree relatives (FDRs) of patients with venous thromboembolism (VTE) and thrombophilia should be screened, followed, and prescribed prophylaxis during risk periods. We recruited consecutive probands with idiopathic VTE and thrombophilia from our thrombosis clinics. Those FDRs with thrombophilia were randomized in family clusters to receive one-time verbal counseling and no organized follow-up or counseling, educational material, reminder aids and follow-up. Only 203 of 1,129 FDRs were eligible and consented. Dropouts were common; 1 FDR (1.7%) developed VTE. VTE risk, ability to treat and prevent were underestimated by the participants. Patients with VTE and thrombophilia and their FDRs are often not interested in thrombophilia testing. Despite education to inform their knowledge, interest and follow-up were less than ideal. The question of the best educational approach in these patients remains unanswered. The value of testing and following asymptomatic carriers of probands with VTE and thrombophilia remains unknown.