The recommended duration of
anticoagulation in the VTE patients is dependent on the persisting risk of re-thrombosis
and bleeding. It was noted that in 10
years follow up after cessation of the anticoagulation nearly 50% of the patients
develop a recurrent VTE episode. This indicates that there is hidden risk of
thrombosis in these patients. It may be due to underlying known or unknown, old
or new risk factors. In these patients may have persistent old factors (of varying
intensity) or newly added risk factors. So, in the beginning it was felt that the
anticoagulation should be continued even after discharge from the hospital, but
they were not sure about the duration. Now, the prophylaxis guidelines
recommend us to extend the thrombo-prophylaxis after hip replacement surgery
for at least 35 days. Similarly, in the
treatment segment also, there was discussion about continuation anti coagulation
beyond 6 months after the indexed event. Placebo controlled trials were done
and they showed 82% relative risk reduction of VTE (Einstein II). In the recent past (Einstein Choice study) in
another study, the anticoagulation was extended for another 1 year to its to
study effect on prevention of rec VTE! It was again found that there is benefit
of anticoagulation (Relative risk reduction of recurrent VTE up to 60%) without
increasing the significant bleeding risk. The relative risk reduction can be as
high as 60% with rivaroxaban. That leaves us with a question that is - how far
is far enough with anticoagulation therapy? Someone can consider giving anticoagulation
for 10 years with annual reviews of the risk factors for re-thrombosis and
bleeding. This means, we need to use the
existing drugs optimally or find out drugs which are effective and safe across all
subsets of patients with thrombotic (VTE) complications, for a period of one decade
after the indexed event of VTE.
