High detection rates of antithrombin deficiency and antiphospholipid syndrome in outpatients aged over 50 years using the standardized protocol for thrombophilia screening

Abstract

Introduction: Thrombophilia screening has limited detection efficiency. We assessed the detection rate when a standardized approach to thrombophilia-screened outpatients was used.

Methods: We analyzed 1185 patients (36.5% males, median age: 43 years [IQR 33-54]) referred to a single center from January 2014 to October 2017 with 11 different clinical indications for thrombophilia screening, which was performed in the adherence to published guidelines. Factor V Leiden, prothrombin G20210A mutation, antithrombin (AT), protein C, protein S deficiencies and antiphospholipid syndrome (APS) were determined.

Results: The overall positivity rate was 37.1% (95% CI 34.3%-39.7%). The highest positivity rate was found in women following VTE during pregnancy/childbirth (64.1%) and provoked VTE patients with positive family history (52.9%). In patients aged >50 years (32.5%), APS was found at a similar rate as in younger subjects (11.4% vs 10.1%), while AT deficiency was detected more frequently in the older group (5.7% vs 2.4%, p = 0.003).

Conclusions: Standard indications for thrombophilia screening lead to detection rates of 37% or more. Frequent detection of APS and AT deficiency among older patients, which often implies a need for long-term anticoagulation and could impact clinical practice patterns, suggests a benefit of thrombophilia screening in this population in selected clinical circumstances.

Keywords: Antiphospholipid syndrome; Antithrombin deficiency; Thrombophilia; Thrombophilia screening; Venous thromboembolism.