Prevalence of confirmed antiphospholipid syndrome in 18-50 years unselected patients with first unprovoked venous thromboembolism.

BACKGROUND: Antiphospholipid syndrome (APS) is an acquired thrombophilia disorder with prevalence not completely known in patients with first unprovoked venous thromboembolic events (VTE). Recent data suggest that the management of some APS patients should be different from that of patients with other thrombophilia. Our aim was to estimate the prevalence of APS in a community-based cohort of patients with a first unprovoked VTE.
METHODS: We conducted a cross-sectional study analyzing data from our computer assisted oral anticoagulant dosage program. Data of all consecutive patients aged 18 to 50 years who were seen between January 1, 2002 and December 31, 2011 for a first proximal unprovoked VTE were extracted. The prevalence and main features of patients who fulfilled the Sapporo revised criteria for APS were collected. RESULTS AND DISCUSSION: A total of 524 incident patients aged 18 to 50 years were included in the anticoagulation clinic during the study period. Of them, 491 were tested for APS and 44 (9.0%; 95% confidence interval [CI]: 6.7-11.8) fulfilled APS criteria. Of 26 APS women, 8 (30.8%) were on combined oral contraceptive pill at the time of VTE, versus 108 (55.1%) in non-APS women (P = .02). No difference was observed between APS and non-APS patients in terms of gender or type of VTE. The prevalence of APS is high in young patients with a first unprovoked VTE. In the direct oral anticoagulant era, when and how to test for APS is challenging and deserves further investigation.