Magazine article Clinical Psychiatry News

Compared with Trials, Warfarin Is Half as Effective at Stroke Prevention in Real World

Magazine article Clinical Psychiatry News

Compared with Trials, Warfarin Is Half as Effective at Stroke Prevention in Real World

Article excerpt

NEW ORLEANS -- Real world experience with warfarin suggests that it is not as good at preventing strokes among patients with atrial fibrillation as clinical trial results suggested, especially among African Americans.

A review of more than 23,000 Medicare patients with atrial fibrillation showed that overall, warfarin prophylaxis cut the stroke rate by 34%, compared with a 65% cut in strokes that's been consistently seen in clinical trials, Brian F. Gage, M.D., reported at the 30th International Stroke Conference.

This lower efficacy is "disappointing," said Dr. Gage, an internist at Washington University in St. Louis.

But warfarin performed even worse among the African Americans in the study. In this group, warfarin use was associated with a trend toward more strokes, although this increase was not statistically significant, compared with African Americans not on warfarin.

The study used a national sample of 23,657 Medicare patients with atrial fibrillation treated during April 1998 though March 1999. Warfarin prophylaxis was used by 43% of African Americans in the study and by 50% of the white patients.

Information culled from the medical records of the patients on warfarin therapy showed that this prophylaxis was often used in a less-than-ideal manner. Patients who regularly receive warfarin should have their dosage adjusted based on their international normalized ratio (INR), a measure of clotting time. Ideally, INRs should be measured about every 28 days in patients who regularly take warfarin.

Among all white patients, the average time between INR measurements was 26 days; among African Americans it was 30 days. …

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