Skip Navigation U.S. Department of Health and Human Services
Agency for Healthcare Research Quality
Archive print banner

Patient Safety and Quality

This information is for reference purposes only. It was current when produced and may now be outdated. Archive material is no longer maintained, and some links may not work. Persons with disabilities having difficulty accessing this information should contact us at: Let us know the nature of the problem, the Web address of what you want, and your contact information.

Please go to for current information.

Use of a visual medication schedule and brief physician counseling can reduce time to anticoagulation control

A new study suggests a simple strategy to enhance warfarin medication safety and efficacy for at-risk patients. Use of warfarin and other anticoagulants is the cornerstone of care for patients with atrial fibrillation (rapid, irregular heartbeat) and other conditions associated with complications of blood clots. However, warfarin use has to be carefully monitored to make sure that patients stay within the therapeutic range. Falling outside this range puts patients at risk of stroke (if blood remains too thick) or bleeding (if blood is thinned too much).

Anticoagulant care often requires warfarin dose adjustments and a medication schedule of varying daily dosages. Miscommunication between physicians and patients about warfarin dosing is common and is a key reason for poor anticoagulant control and adverse medication events.

To enhance patient-physician communication about warfarin regimens, a team from the University of California, San Francisco, developed a computer-generated visual medication schedule (VMS). It included digitized color images of one or more warfarin pills, with the exact dosage for each pill, on a chart for each day of the week. The team randomly assigned 147 chronic warfarin users from an anticoagulation clinic either to usual care or to receive a VMS along with brief counseling at each visit.

At baseline, a similar proportion of patients and clinicians from the VMS and usual care groups had different understandings about the prescribed warfarin regimen (38 vs. 42 percent). Patients who received the visual medication schedule achieved anticoagulation control 2 weeks more quickly than controls (median of 28 vs. 42 days). Those who originally disagreed about the regimen with their doctor, either due to language barriers, inadequate health literacy, or other factors, benefited even more from the intervention. This group achieved anticoagulation control 3 weeks earlier than controls (median 28 vs. 49 days). The study was supported in part by the Agency for Healthcare Research and Quality (HS10856).

See "A visual medication schedule to improve anticoagulation control: A randomized, controlled trial," by Edward L. Machtinger, M.D., Frances Wang, M.A., Lay-Leng Chen, M.D., and others, in the October 2007 Joint Commission Journal on Quality and Patient Safety 33(10), pp. 625-635.

Return to Contents
Proceed to Next Article


The information on this page is archived and provided for reference purposes only.


AHRQ Advancing Excellence in Health Care