PET Scans and Diagnosing Alzheimer’s

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In 1906, Dr. Alzheimer first discovered plaques on the brain while conducting an autopsy of a patient who had had severe dementia. For the next 105 years, physicians continued to confirm an Alzheimer’s diagnosis by autopsy; there was no other way to know if the patient’s brain had the plaques and tangles considered to be the hallmarks of this disease.

The possibility of diagnosing patients while living arose in 2011 when the FDA approved a PET scan process using Amyvid, a radioactive tracer. Amyvid is manufactured by a subsidiary of Eli Lilly Pharmaceuticals. When injected into a human, Amyvid attaches itself to amyloid deposits (plaques) in the brain. After being injected with the tracer, the patient undergoes a PET scan, which generates 3 dimensional images. These images pinpoint whether one has plaques, and the amount and the locations in the brain. The scan costs roughly $3,000.

For months, there has been a vigorous debate whether Medicare should cover the cost of PET scans to help diagnose Alzheimer’s.  CMS, the government department that oversees the Medicare program, issued a proposed decision in July 2013 which denied coverage. It requested public input and received hundreds of comments.

The Arguments For Covering the Cost of PET Scans

Eli Lilly, the Alzheimer’s Association, the Society of Nuclear Medicine and Molecular Imaging, and some members in the Alzheimer’s research community supported expanded use of the PET scan. As many have noted, these supporters, either directly or indirectly, stand to benefit from the expanded use of PET scans.  Among the benefits of testing, these groups cited the following benefits:

  • Earlier access to appropriate treatments
  • Adequate time to complete advanced directives and financial planning
  • Enabling enrollment in clinical trials
  • Eliminating uncertainty and allowing families time to educate themselves and to establish support systems
  • Allowing those who have been incorrectly diagnosed with Alzheimer’s Disease to get off of unnecessary drugs

The Arguments Against Covering the Cost of PET Scans

Other Alzheimer researchers, health policy analysts, and members of the public challenged these arguments. They focused on two points:

  • Knowing one has amyloid deposits neither results in different treatments nor improves the quality of the patient’s life because there is no effective treatment for the disease.
  • The presence of amyloid is not a determinative diagnostic finding.  Ironically, since the advent of Amyvid, researchers have been able to track the presence of amyloid and assess its connection to Alzheimer’s.  In recent studies, between 30 and 40% of people found to have amyloid deposits never progressed to cognitive impairment. Therefore, a positive scan is not dispositive for Alzheimer’s.  Expanded use of scans will result significant numbers of people being told they have Alzheimer’s when they do not, resulting in unnecessary suffering and anxiety.

Final Ruling by CMS

Last week, CMS issued its final ruling on this matter. Under the law, CMS may not approve coverage for items or services that are not “reasonable and necessary for the diagnosis or treatment of an illness…”

The CMS ruled that, in general, there is insufficient evidence that the scans are “reasonable or necessary” for diagnosing or treating Alzheimer’s. The ruling does allow coverage for one PET scan per person under two limited circumstances:

  • To rule out Alzheimer’s in difficult clinical cases, such as when other diagnostic tests are inconclusive as to whether a person has Alzheimer’s or frontotemporal dementia
  • To enhance approved clinical trials by allowing for patient selection based on biologic factors as well as other criteria.  The ruling places many conditions on the type of clinical trial that will qualify for coverage, and requires the investigators to collect evidence that will ultimately help CMS and the scientific community determine when patients are most likely to benefit from the use of scans.

In the weeks leading up to the issuance of the final ruling, there was a spate of articles suggesting that CMS’s failure to approve coverage for these scans was denying patients access to effective treatment. However, an objective look at the state of the science makes one conclude that CMS has done a responsible job in allowing scans where they could improve the quality of a person’s life (by definitely ruling out one form of dementia) or where they can be used in an organized way to accelerate the industry’s understanding of how to best use this technology.

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