Mild Antithrombin Deficiency and the Risk of Recurrent Venous Thromboembolism: A Prospective Cohort Study.
Circulation. 2013 Oct 21;
Authors: Di Minno MN, Dentali F, Lupoli R, Ageno W
BACKGROUND: Antithrombin (AT) deficiency, defined by AT levels of less than 70%, is a major thrombophilic condition associated with an increased risk of venous thromboembolism (VTE). No prospective data are available about the risk of recurrent VTE associated with mildly decreased AT levels (70-80%).
METHODS AND RESULTS: Consecutive patients with a first VTE were stratified according to functional AT levels (<70%; 70-80%, >80%) and were followed-up for a mean of 8.70 years to assess the incidence of VTE recurrence. A total of 823 patients (mean age 48.3, males 41.9%) were enrolled. Recurrent VTE occurred in 253 patients (3.53% patients-year). Stratifying for AT levels, VTE recurrence occurred in 19 (5.90% patients-year) <70%AT patients, in 20 (5.35% patients-year) of the 70-80%AT patients and in 214 patients (3.31% patient-year) with >80%AT. After adjusting for major VTE risk factors and for anticoagulation duration, the risk of VTE recurrence was significantly higher in patients with <70%AT (HR: 3.48, 95%CI: 2.16-5.61) and 70-80%AT (HR: 2.40, 95%CI: 1.51-3.80) as compared to >80%AT patients. When the population was stratified according to the presence or absence of major risk factors for the index event, the association remained significant only in patients with unprovoked VTE.
CONCLUSIONS: The presence of mild AT deficiency (70%-80% AT) in patients with unprovoked VTE is associated with a significantly increased risk of recurrence and should be taken into account when deciding the duration of secondary prevention.
CLINICAL TRIAL REGISTRATION INFORMATION: ClinicalTrials.gov; Unique Identifier: NCT01382550.
PMID: 24146249 [PubMed - as supplied by publisher]