Racial and Ethnic Differences in Initiation and Discontinuation of Antidementia Drugs by Medicare Beneficiaries.

Objectives: To examine racial and ethnic differences in initiation and time to discontinuation of antidementia medication in Medicare beneficiaries.

Design: Retrospective cohort study.

Setting: Secondary analysis of 2009-10 enrollment, claims, and Part D prescription data for a 10% national sample of U.S. Medicare fee-for-service beneficiaries.

Participants: Beneficiaries aged 65 and older with Alzheimer's disease or related dementia (ADRD) before 2009 and no fills for antidementia medications in the first half of 2009 (N = 84,043).

Measurements: Initiation was defined as having one or more fills for antidementia medication in the second half of 2009 and discontinuation as a gap in coverage of 30 days or more during the year after initiation. The Andersen Behavioral Model was used to guide covariate selection.

Results: Overall, 3,481 (4.1%) of previous nonusers initiated antidementia medication in the second half of 2009. Of those initiating one drug class (acetylcholinesterase inhibitors (AChEIs) or memantine), 9% later added the other class, and 2% switched classes. Of initiators, 23% discontinued within 1 month, and 62% discontinued within 1 year. Hispanic beneficiaries were more likely than white beneficiaries to initiate (adjusted odds ratio = 1.25, 95% confidence interval (CI) = 1.10-1.41). Black and white beneficiaries did not differ in likelihood of initiation. Hispanic (adjusted hazard ratio (aHR) = 1.56, 95% CI = 1.34-1.82) and black (aHR = 1.25, 95% CI = 1.08-1.44) beneficiaries discontinued at a faster rate than white beneficiaries.

Conclusion: Initiation of antidementia medications was no different in black and white beneficiaries and more likely in Hispanic beneficiaries; black and Hispanic beneficiaries discontinued at a faster rate. More research into reasons explaining these differences is needed.