This Comment in the Drug and Therapeutics Bulletin (DTB) discusses the results of a non-inferiority study that demonstrated INR monitoring every 12 weeks was as safe as INR monitoring every 4 weeks (see NELM abstract for further details).

The DTB notes that “a 12-week INR testing frequency is probably safe for patients whose INR is stable if they continue to have clinician support. But this is a small single-centre study and the researchers caution that further research is needed before INR testing every 12 weeks can be routinely recommended. They also noted several limitations to their study. Extreme INRs were reported to investigators for ethical reasons, and patients in the 12-week group were contacted by telephone and offered advice and support on INR stability every 4 weeks, which could have artificially improved compliance”.