The long-term risk for recurrent venous thromboembolism (VTE) in patients on extended anticoagulation is “low but not negligible” and both clinicians and patients should be aware of it, researchers say.
An international analysis of data from 26 studies investigated recurrent VTE among patients after a first unprovoked VTE, who after having completed three months of anticoagulant treatment were given extended anticoagulation for at least six months.
Based on 11,631 person-years of follow-up, researchers at the University of Ottawa in Canada found the incidence of recurrent VTE and fatal pulmonary embolism per 100 person-years to be 1.41 and 0.09, with 5-year cumulative incidences of 7.1% and 1.2%, respectively.
The data also showed that the incidence of recurrent VTE was 1.08 per 100 person years in those taking direct oral anticoagulants and 1.55 with vitamin K antagonists, while the case-fatality rate of recurrent VTE was 4.9%.
The study’s findings have important implications for clinical practice, the authors stress in a paper published in the Journal of Thrombosis and Haemostasis.
“Given the high efficacy established for oral anticoagulants in the secondary prevention of VTE, clinicians and patients assume that anticoagulant therapy offers near-total protection against recurrent VTE. However, the possibility of a recurrent VTE during anticoagulant therapy should not be dismissed”.
In the study, recurrent VTE during extended anticoagulation was shown to “represent a considerable long-term burden – 1 in every 14 patients receiving anticoagulant therapy would be expected to experience a recurrent VTE within 5 years”, the authors said.
“Thus, while our results may reassure patients that their prognosis while receiving extended anticoagulation is good, with a low (less than 2% per year) risk of recurrent VTE, the risk is not zero and clinicians ought to keep a low threshold for suspicion of recurrent VTE in [these] patients, and perform thorough diagnostic investigations for suspected [cases].”
The findings should be used to shape patient expectations on longer-term anticoagulation, and to estimate the net clinical benefit of such treatment versus the risk of major bleeding, they concluded.