Risk factors for venous thromboembolism (VTE) recurrences in Thai patients without cancer

Studies in Western countries show that VTE recurrent rates are lower in the presence of a transient provoking factor, older age, female sex and/or hormonal use, while thrombophilia (factor V Leiden or prothrombin mutation) has no predictive role. This study aimed to determine the incidence and risk factors of recurrent VTE in Asian patients.

This is a retrospective cohort study in adult VTE patients who were diagnosed during 2004-2014, had no active cancer and followed-up for at least 1 year.

There were 198 patients. The mean age was 58.2 ± 17.6 years and 68.2% were female. The diagnoses were deep vein thrombosis (56%), pulmonary embolism (32%) or both (12%). They were provoked by major surgery in 21.7%. Thrombophilia (antiphospholipid syndrome or protein C or protein S deficiency) was found in 11.6%. The recurrent rate during the median follow-up time of 52 months was 2.2 (95% confidence interval [CI] 1.46-3.31) per 100 patient-years. Presence of thrombophilia was independently associated with recurrences with the adjusted hazard ratio (aHR) of 3.52 (95% CI 1.32-9.42, p = 0.01). There were 144 patients who discontinued anticoagulants. During the median time of 55 months after stopping anticoagulants, the recurrent rate was 4.3 per 100 patient-years. Thrombophilia was associated with recurrences with aHR of 4.00 (95% CI 1.42-11.31, p = 0.01), while male sex, younger age, provoking conditions and hormone use showed no significant association.

VTE recurrent rate in Asians is comparable to Caucasians, but thrombophilia is the strongest risk factor.