Racial disparities in the filling of warfarin prescriptions for nonvalvular atrial fibrillation

Background. Warfarin has been shown to decrease the rate of thromboembolic events in patients with nonvalvular atrial fibrillation, but it is frequently underprescribed. Our goal was to establish whether there have been racial disparities in the filling of warfarin prescriptions for patients with newly incident nonvalvular atrial fibrillation. Methods: We conducted a retrospective analysis of Ohio Medicaid claims between January 1, 1997 and May 31, 2002, for recipients with newly incident nonvalvular atrial fibrillation. Race was identified from the demographic information in the database, and the analysis was limited to white and African-American patients. The main outcome measure was the filling of a prescription for warfarin at any time between 7 days prior to the initial diagnosis of atrial fibrillation and 30 days after the initial diagnosis. To evaluate the independent role of race in the filling of warfarin prescriptions, we created a multivariable logistic regression model incorporating predictors significant at P < 0.10 in the univariate model. Results: A total of 6283 patients were identified as having newly incident nonvalvular atrial fibrillation, 18.5% of whom were African-American. In general, African-American patients had a higher rate of comorbid illness. Warfarin prescriptions were filled for 9.4% of white patients and 7.6% of African-American patients. When controlling for significant confounders in the multivariable logistic regression model, African-American patients had an adjusted odds ratio for receiving warfarin of 0.76 (95% CI, 0.60-0.98) when compared with white patients. Conclusion: African-American patients in the Ohio Medicaid population between 1998 and 2002 were significantly less likely than white patients to fill a warfarin prescription for newly incident nonvalvular atrial fibrillation.