Small study shows benefit of warfarin for cluster headaches

Key Points

Thirty-four patients with refractory chronic cluster headache received warfarin or placebo for 12 weeks. The target international normalized ratio (INR) for warfarin was between 1.5 and 1.9. Patients were crossed over from 1 treatment to the other after a washout period of 2 weeks. The occurrence of remission lasting 4 weeks or longer was the primary outcome measure.

During the warfarin period, 17 patients (50%) had remission for 4 weeks or longer vs. 4 patients (11.8%) during the placebo period (P=.004). During warfarin treatment, frequency, duration, and intensity of cluster attacks were all significantly lower (P<.01).

Source: Hakim SM. Warfarin for refractory chronic cluster headache: A randomized pilot study. Headache. 2011;51:713-725.

Warfarin and dental procedures: To hold or not?

A common question from dentists and patients is whether warfarin needs to be interrupted for various dental procedures. Among other investigations, one recent multicenter study found that dental extractions can safely be performed in anticoagulated outpatients without altering their ongoing anticoagulant therapy. Many dentists, however, remain hesitant to perform such procedures for these patients despite evidence suggesting their safety.

Publications outlining best management of patients on warfarin, a vitamin K antagonist (VKA), are available. The American College of Chest Physicians guidelines state, "In patients who are undergoing minor dental procedures and are receiving VKAs we recommend continuing VKAs around the time of the procedure and coadministering an oral prohemostatic agent." The British Committee for Standards in Haematology guidelines state, "The risk of significant bleeding in patients on oral anticoagulants and with a stable INR in the therapeutic range 2-4 (i.e. <4) is very small and the risk of thrombosis may be increased in patients in whom oral anticoagulants are temporarily discontinued. Oral anticoagulants should not be discontinued in the majority of patients requiring outpatient dental surgery including dental extraction."

An important factor in the decision to maintain or discontinue warfarin is communication between the dentist and the healthcare provider who manages the patient's warfarin. Pharmacists can play a pivotal role in these situations by educating patients and dentists about the evidence and guidelines.

Sources: Bacci C, Maglione M, Favero L, et al. Management of dental extraction in patients undergoing anticoagulant treatment. Results from a large, multicentre, prospective, case-control study. Thromb Haemost. 2010;104:972-975. Douketis JD, Berger PB, Dunn AD, et al. The perioperative management of antithrombotic therapy. American College of Chest Physicians evidence-based clinical practice guidelines (8th edition). Chest. 2008;133(6 suppl):299S-339S. British Committee for Standards in Haematology. Guidelines for the management of patients on oral anticoagulants requiring dental surgery. 2007. http://www.drugtopics.com/bcsh_guidelines.

Vitamin E affects stroke risk

A large meta-analysis of 9 placebo-controlled trials encompassing approximately 119,000 patients found that vitamin E supplementation increases the risk of hemorrhagic stroke by 22% while reducing ischemic stroke by 10%. Overall total stroke risk was not different.

The mechanism behind an increased bleeding risk with vitamin E is not yet understood. Possible mechanisms under consideration include a potential antiplatelet effect or an inhibitory effect on the activation of certain clotting factors. Stroke is a leading cause of death and disability. Vitamin E supplements are widely used and readily available, so any evidence to a link between Vitamin E and strokes is of public health importance.

Because hemorrhagic strokes typically result in more severe outcomes, the authors advise against the use of vitamin E even though a small benefit is possible relative to ischemic stroke.

Source: Schürks M, Glynn RJ, Rist PM, Tzourio C, Kurth T. Effects of vitamin E on stroke subtypes: Meta-analysis of randomised controlled trials. BMJ. 2010;341:c5702.

Anna Garrett is manager, Outpatient Clinical Pharmacy Programs, Mission Hospital, Asheville, N.C., and president and founder of the National Association of Women in Health Care ( http://www.nawhc.com/). She also is a Drug Topics board member. She can be reached at anna.garrett@msj.org
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