Apixaban vs vitamin K antagonists in relation to postthrombotic syndrome: data from a prospective cohort study

BACKGROUND: Postthrombotic syndrome (PTS) is a prevalent complication following deep vein thrombosis (DVT) of the leg. Direct oral anticoagulants are recommended for the treatment of DVT due to their lower bleeding risk and comparable effectiveness to vitamin K antagonists (VKAs). Previous studies suggest that rivaroxaban may reduce the risk of PTS compared with VKAs. OBJECTIVES: To compare the incidence of PTS in DVT patients treated with apixaban vs VKAs. METHODS: Adults with DVT of the leg, recruited between 2003 and 2022 in a Maastricht University Medical Center prospective cohort, were eligible for analysis. In 2017, prescription guidelines changed from VKAs to apixaban for new patients. Patients received anticoagulation treatment according to (inter)national guidelines, along with elastic stockings for at least 6 months. Multivariable-adjusted logistic regression analyses were performed to assess the relationship between apixaban vs VKA use and PTS occurrence. PTS was defined as a Villalta score ≥5 at least 6 months after DVT. RESULTS: PTS was diagnosed in 28.0% of patients treated with apixaban and in 35.7% treated with VKAs. The odds were significantly lower in both unadjusted (odds ratio OR, 0.70; 95% CI, 0.50-0.98) and multivariable-adjusted models (adjusted for age, sex, and body mass index: OR, 0.62; 95% CI, 0.44-0.88). Moderate-severe PTS was diagnosed in 4.1% of patients treated with apixaban and in 8.4% treated with VKAs (adjusted for age, sex, and body mass index: OR, 0.42; 95% CI, 0.20-0.87). Also in obese patients, the odds of PTS were significantly lower with apixaban compared with VKAs (adjusted for age and sex: OR, 0.44; 95% CI, 0.24-0.84). CONCLUSION: Apixaban was associated with reduced PTS risk and severity, particularly in obese patients.