Conclusion
Knowledge on the effects of statin treatment initiating on anticoagulation in stable VKA treatment is limited. Despite different types of VKA and statins, a tendency of an increased anticoagulant effect following statin treatment, when initiated while in VKA treatment was observed in the included studies. Considering initiation of simvastatin treatment in patients treated with warfarin, the reported increase in anticoagulation is limited and overall considered to be without clinical relevance. The anticoagulant effect of initiation of other statins vary, and it should be evaluated individually, if the frequency of INR monitoring should be increased during the first period of concomitant treatment.