After listening to last-minute appeals by nuclear medicine advocates on Jan. 10, a government panel recommended not reimbursing for PET imaging for Alzheimer's disease (AD) and mild cognitive impairment (MCI).
The five-member panel unanimously agreed that evidence was insufficient to support reimbursement for FDG-PET to diagnose AD and MCI.
PET advocates have another round before throwing in the towel. The executive committee of the Medicare Coverage Advisory Committee (MCAC), which is looking at the recommendation, will hold an open meeting on April 16. But last week's double-punch ruling has left the PET community reeling. Unless strong additional data appear between now and April, the Society of Nuclear Medicine probably won't attend the meeting.
"I don't think the executive committee, when it hears the panel's unanimous negative decision, will turn the recommendation around," said Dr. Peter Conti, who represented the SNM at the Jan. 10 meeting.
In evaluating the application, the Agency for Healthcare Research and Quality used a "treat all" standard to measure the improvement of outcomes. This standard, which holds that everyone with memory impairment be given drugs, makes the more definitive PET diagnosis unnecessary. The risks associated with treating everyone are lower than potential misdiagnoses with PET, according to the AHRQ.
"This is the first time I've heard of an accurate diagnostic test being rejected in favor of a less definitive approach," said Conti, director of the PET imaging science center at the University of Southern California. "This means we can have up to 40% of patients taking drugs who don't have a diagnosis of AD or MCI. Even if the effects of the drugs are benign, their costs are not."
Some members of the PET community, although disappointed with the recommendation, agree that published evidence is lacking.
"I can't say there isn't some basis for the recommendation because there are not a lot of prospective well-controlled studies in the literature," said Dr. Carolyn Cidis Meltzer, medical director of the PET facility at the University of Pittsburgh. "Of course, I disagree with it. I know from my clinical practice and from a number of smaller studies that PET can clearly add clinical information to making a diagnosis of Alzheimer's or to excluding Alzheimer's and other types of dementia."
Before the imaging panel made its recommendation to the MCAC, Conti told the assembly that the evidence strongly supports the value of FDG-PET as an alternate diagnostic approach for AD. The panel looked for evidence in several areas:
- PET's ability to differentiate dementia subtypes, thereby facilitating earlier treatment of AD
- PET's ability to identify patients with MCI who would develop AD
- PET's effectiveness as a screening tool for patients with a family history of AD
Some nuclear medicine advocates have suggested the panel -- perhaps rightly -- was concerned that PET would be used too broadly and inappropriately in all patients with memory complaints. Although PET is helpful in certain cases when a definitive clinical diagnosis for Alzheimer's exists, its effectiveness in detecting early MCI has not been shown.
"There are suggestions PET will be helpful with MCI, but we don't know the exact sensitivity and specificity for predicting whether a patient with MCI will develop Alzheimer's," Meltzer said.
After the spring meeting, MCAC will hand over its recommendation to the coverage and analysis group of the Centers for Medicaid and Medicare Services, which should render a decision within 60 days. Comments can be sent to CMS during this period.
-- By C.P. Kaiser
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