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New Model Predicts Bleeding Risk in Elderly Warfarin Recipients
By Will Boggs, MD NEW YORK (Reuters Health) Dec 08 - A research group has developed and validated a contemporary model for bleeding risk in elderly patients with atrial fibrillation receiving warfarin, according to a report in the November issue of Chest. "Consideration of the variables we have described can help clinicians identify older persons at low risk for bleeding events and improve the prescribing of warfarin in stroke prevention," Dr. Theresa I. Shireman from the University of Kansas Medical Center, Kansas City, told Reuters Health. Dr. Shireman and colleagues collected data on 26,000 patients with AF from a registry of atrial fibrillation, and used Medicare claims to identify bleeding events requiring hospitalization. Candidate variables related to bleeding were selected for development of their model, incorporating three risk categories. After a stepwise selection process, the 8 variables remaining in the model included age at least 70 years, female gender, remote bleeding event, recent bleeding event, alcohol or drug abuse, diabetes, anemia, and antiplatelet drug use. "We were surprised that hepatic and renal failure were not significant and that other medications associated with bleeding risks were also not significant," Dr. Shireman said. In the validation sample, the team reports, major bleeding events occurred in 0.9% of the low-risk individuals, 2.0% of the moderate-risk individuals, and 5.4% of the high-risk individuals. Pair-wise comparisons showed all these rates to be significantly different from each other. Based on Kaplan-Meier curves and c statistics, the new model provided better discrimination than two other currently used models among the bleeding risk groups. This model also allows the separate quantification of the effects of each risk factor, the researchers note. "Validation of this model in other study populations is warranted," they suggest. "Risk/benefit stratification schemas are designed to aid management decisions; and for bleeding risk, the new model by Shireman et al. looks very promising," Dr. Puneet Kakar and colleagues from University Department of Medicine, City Hospital, Birmingham, UK write in a related editorial. "As is often the case, many patients who are at the highest risk of a bleed are also at the highest risk of having a stroke, and this clearly poses problems in management. Ultimately," the editorial concludes, "it may still be up to the patient and treating physician to decide each case on an individual basis." Chest 2006;130:1390-1396,1296-1299.
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