A Real-world Analysis of Treatment Patterns for Cholinesterase Inhibitors and Memantine among Newly-diagnosed Alzheimer's Disease Patients

Introduction: Alzheimer's disease (AD) is the most common neurodegenerative form of dementia. Pharmacological therapies for symptomatic treatment, such as acetylcholinesterase inhibitors (AChEIs) and memantine, have been available in the USA since 2000. Over the past decade, few studies have analyzed real-world anti-dementia treatment patterns in the USA. This study evaluated monotherapy AChEIs and memantine treatment patterns among newly diagnosed AD patients.

Methods: A retrospective cohort study was conducted using Medicare data and the Minimum Data Set from 2008 to 2012. Patients aged 65-100 years with newly diagnosed AD (ICD-9 code: 331.0) and monotherapy AChEI or memantine treatment initiated after diagnosis were included. Descriptive treatment pattern analyses, including discontinuation and switch, were undertaken. Kaplan-Meier curves were developed to examine the treatment duration.

Results: A total of 9812 newly diagnosed AD patients were identified, with 56.7% (n = 5567) first receiving anti-dementia treatment after the initial AD diagnosis. Among patients initiating monotherapy AChEIs or memantine after AD diagnosis (N = 5200), 51.6% continued index treatment during the entire follow-up period (mean follow-up: 659.7 days) and 21.7% discontinued treatment. Of those who initiated monotherapy treatment with an AChEI, 11.1% received adjunct therapy with memantine. Among patients with ≥1 year of continuous treatment (mean follow-up: 834 days), 75.6% remained on the index drug, 10.2% discontinued during the remaining follow-up period, and 9.5% of the AD patients initiating AChEIs received adjunct memantine therapy during the remaining follow-up period.

Conclusion: In the USA Medicare population, about 50% of the patients who initiated treatment with AChEI or memantine after diagnosis continued the index treatment, and more than 20% discontinued and were untreated afterwards over the observation period. AD patients initiating AChEIs or memantine were more likely to remain on their treatment if they were persistently treated for the first year.