In the June 2016 article, “Could the Lack of an Efficient and Affordable Diagnostic Pathway Limit Market Access for New Alzheimer’s Treatments?"1 the author and column editor would like to clarify several points. While Medicare reimbursement for generalized commercial use of positron emission tomography (PET) imaging currently does not exist, Medicare clearly finds the test valuable to assist with diagnosis and provides reimbursement for PET amyloid-beta imaging in clinical research studies and for FDG-PET to rule out Alzheimer’s disease (AD) in the differential diagnosis vs frontotemporal dementia.2,3
Current therapies for AD were said to provide “mild symptomatic relief;” it should be noted that there are available agents that provide significant, if temporary, symptomatic relief. The parenthetical definitions of the terms “sensitive” and “specific” as they relate to diagnostic testing were inadvertently transposed.
The article made a cost assumption based on everyone over the age of 65 years receiving diagnostic PET imaging to identify those who may benefit from novel therapeutics nearing the market. The prevalence of AD in those over 65 years of age is estimated at 4.7 million people.4 Although this is a more reasonable population in which to conduct PET imaging to assess the buildup of amyloid plaque, identifying patients with AD with early symptoms would presumably require testing significantly more patients. While PET imaging is the current gold standard, the authors continue to concern themselves with finding patients in the prodromal to very mild stages of the disease—the patient population expected to benefit most from therapies in late-phase development. How to derive this subset from the potential population is the challenge facing researchers. The Mini-Mental State Exam (MMSE) and Montreal Cognitive Assessment (MoCA) are used today as part of the diagnosis of early-stage AD.
References
1. Lifsitz R, Blandford L. Could the lack of an efficient and affordable diagnostic pathway limit market access for new Alzheimer’s treatments? J Clin Pathways. 2016;2(5):29.
2. Centers for Medicare and Medicaid Services. Decision memo for beta amyloid positron emission tomography in dementia and neurodegenerative disease (CAG-000431N). https://www.cms.gov/medicare-coverage-database/details/nca-decision-memo.aspx?NCAId=265. Published September 27, 2013. Accessed July 7, 2016.
3. Centers for Medicare and Medicaid Services. Decision memo for positron emission tomography (FDG) and other neuroimaging devices for suspected dementia (CAG-00088R). https://www.cms.gov/medicare-coverage-database/details/nca-decision-memo.aspx?NCAId=104. Published September 15, 2004. Accessed July 7, 2016.
4. Hebert LE, Weuve J, Scherr PA, Evans DA. Alzheimer disease in the United States (2010-2050) estimated using the 2010 census. Neurology. 2013;80(19):1778-1783.
