A new Alzheimer’s drug with “modest clinical benefit” could spur hundreds of millions in spending on medical imaging, according to an analysis published May 11 in JAMA Internal Medicine [1].

In January, the U.S. FDA granted accelerated approval for lecanemab (brand name Leqembi) to treat the progressive brain disorder, with the administration’s traditional endorsement possibly following sometime this year. The drug carries a proposed annual acquisition cost of $26,500 and requires additional services such as a baseline PET scan and follow-up MRIs after infusions.

“Lecanemab and associated ancillary services could add an estimated $2 billion to $5 billion annually to Medicare spending with substantial out-of-pocket costs for beneficiaries lacking supplemental coverage,” John N. Mafi, MD, with the David Geffen School of Medicine at UCLA, and co-authors wrote Thursday.

For the study, researchers utilized data from both traditional and Medicare Advantage, incorporating beneficiaries age 65 or older with mild cognitive impairment or mild dementia prevalence. They also examined claims specific to 2019, which comprised 51.6 million Americans. Mafi et al. used prior studies and input from experts to assume that 35% of patients who screened positive for mild cognitive impairment or mild dementia would undergo formal neurocognitive testing. Of those, half would receive a positron emission tomography scan, while between 37% (the “lower bound” estimate) to 68% (“upper bound” estimate) would test positive for amyloid plaque.

To approximate spending, the team performed a cost analysis using nationally representative survey data from the 2018 Health and Retirement Study. Among nearly 7,600 HRS participants—extrapolated to represent 44 million Medicare beneficiaries—16.2% had MCI or mild dementia. Researchers calculated per-beneficiary medication costs of $25,851 and ancillary costs of $7,330. If 85,687 eligible patients received lecanemab, representing the lower-bound estimate, Medicare would spend $2 billion on the drug or $5.1 billion (on 216,536 beneficiaries) for the upper-bound estimate.

Mafi and co-authors estimated each beneficiary would receive one PET scan per year and three routine MRI scans of the brain. This would result in annual Medicare spending of $107.3 million to $271.1 million for the former and $91.5 million to $231.3 million for latter. The federal program would tally $1,252 per beneficiary each year on PET scans and $1,068 for MRIs. Patients, on the other hand would face out-of-pocket costs as high as $313 and $267 for the two imaging services, respectively.

The research has several limitations, the authors cautioned.

“We did not account for rebates, price changes, or societal costs, such as caregiver burden, which may shift due to transportation to infusions and appointments or changes in patients’ cognitive function,” Mafi and colleagues concluded. “Despite incorporating increases in cognitive screening and case positivity rates, these estimates are conservative; changes in physician behavior, cognitive screening capacity and demand, new diagnoses of MCI or mild dementia, and associated spending may increase more than anticipated.”