Drug-drug interaction between warfarin and statins: A Danish cohort study

Anna E Engell, Andreas L O Svendsen, Bent S Lind, Christen L Andersen, John S Andersen, Tora G Willadsen, Frederik Persson, Anton Pottegård

16 Citationer (Scopus)


Initiation of statin treatment is suggested to increase the international normalised ratio (INR) among warfarin users. However, available data is limited and conflicting. We conducted a register-based cohort study to evaluate the drug-drug interaction between warfarin and statins. By linking data on INR measurements and filled prescriptions, we identified warfarin users 2000-2015 initiating simvastatin (n=1,363), atorvastatin (n=165), or rosuvastatin (n=23). Simvastatin initiation led to an increase in mean INR from 2.40 to 2.71, with INRs peaking after 4 weeks, corresponding to a mean change of 0.32 (95%CI 0.25-0.38). High-dose and low-dose simvastatin led to comparable changes (mean change 0.33 vs 0.29). Initiation of atorvastatin and rosuvastatin lead to INR increases of 0.27 (95%CI 0.12-0.42) and 0.30 (95%CI -0.09-0.69). In conclusion, initiation of simvastatin, atorvastatin, or rosuvastatin among warfarin users led to a minor increase in INR. The magnitude of this change is for most patients likely of limited clinical relevance.

TidsskriftBritish Journal of Clinical Pharmacology
Udgave nummer2
Sider (fra-til)694-699
Antal sider6
StatusUdgivet - feb. 2021


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