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Trial to prove utility of amyloid imaging seeks physicians for referrals

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A chance to demonstrate what many suspect

Times have changed.

When I was a medical student in the early 1980s, the prevailing philosophy seemed to be that Alzheimer’s disease was diagnosed on the basis of negative tests, and that less-common causes of dementia, such as Pick’s disease, were clinically indistinguishable and identifiable only at autopsy. With greater neuropsychological sophistication and a wave of newly trained behavioral neurologists, Alzheimer’s disease was clinically identifiable as a distinct syndrome that was readily distinguished in most cases from other forms of dementia.

Technological breakthroughs have now added biomarkers to the diagnostic armamentarium. Despite the considerable progress that has been made in understanding the neurobiology of Alzheimer’s disease and the refinements in its diagnosis, therapy has lagged woefully. Modest symptomatic measures are available, but no one would argue that the current state is even close to satisfactory.

Dr. Richard J. Caselli

Molecular imaging, such as amyloid PET and more recently tau PET, can image specific pathology and very obviously can aid in the diagnosis of Alzheimer’s disease. Amyloid PET is not perfect, though. Patients can have neurofibrillary tau tangle–only Alzheimer’s with a negative scan, and normal elderly controls with positive scans may fail to exhibit signs of dementia prior to their ultimate demise. A patient suspected of having Alzheimer’s has limited therapeutic options, and because they are all symptom based, they vary little based on whether the true diagnosis is Alzheimer’s, frontotemporal dementia, or Lewy body dementia.

New therapeutic agents being tested in research trials are a different matter and clearly need to be administered to a pathologically appropriate substrate, which molecular imaging can clarify. Because of the clinical limitations, however, CMS [Centers for Medicare & Medicaid Services] elected to withhold reimbursement of amyloid PET – a decision that has frustrated dementia specialists and families seeking definite evidence of a progressive, incurable, fatal disorder.

The IDEAS study is our chance to demonstrate what many suspect: that molecular imaging can provide more definite answers, and that such answers are most needed in diagnostically challenging cases.

Since amyloid PET will be reimbursed under the terms of this trial, our field has a golden opportunity to prove the clinical value of amyloid PET. We are all encouraged to contribute to its completion and hope for its success.

Dr. Richard J. Caselli is a professor of neurology at the Mayo Clinic in Scottsdale, Ariz., and clinical core director of the Arizona Alzheimer’s Disease Center, Phoenix. He has no relevant disclosures.

This commentary was updated October 29, 2015.


 

References

A major study aimed at proving the clinical utility of amyloid imaging in diagnosing dementia is now recruiting participating physicians.

The IDEAS (Imaging Dementia – Evidence for Amyloid Scanning) Study, sponsored by the Alzheimer’s Association and managed by the American College of Radiology, seeks to enroll 18,488 patients aged 65 years and older with progressive, unexplained mild cognitive impairment or dementia of uncertain cause. The study will evaluate how knowing a patient’s amyloid status might affect clinical decision-making and health care utilization over 12 months. Patients will begin to enter the study early next year.

The scope of the $100 million study is unprecedented, said Maria Carrillo, Ph.D., chief science officer of the Alzheimer’s Association and cochair of the study.

“The Alzheimer’s Association is leading the IDEAS Study because we understand the importance of early and accurate diagnosis and management of dementia for individuals with the disease and their families,” she said in a statement. “There has never been a study of this scale to evaluate the clinical value of brain amyloid imaging in diagnosing and caring for those affected by Alzheimer’s.”

Physicians who participate will team with radiologists and nuclear medicine physicians at PET facilities; everyone will consent to fulfilling study training, data, and timeline requirements. Study referrals must come from dementia specialists who are registered as participating in the trial. Once accepted, a patient will undergo one amyloid PET scan and be followed for 12 months. The scans will be paid for under the CMS Coverage with Evidence Development policy.

The study will collect data in two areas:

• How the scan affects patient management in the first 90 days after the procedure, comparing actual postscan management to the prescan intended management. Outcomes here include the use of Alzheimer’s drugs, other medications, and counseling about safety and future planning.

• How the scan affects 12-month medical outcomes in both patients and controls. This analysis will be based on Medicare claims data; the primary objective is to learn whether amyloid imaging is associated with any significant reductions in outcomes such as hospitalization and emergency department visits. Health resource utilization will also be examined.

By examining these data, the study aims to show that amyloid imaging early in the disease process will improve both clinical and financial outcomes. If this can be established, the goal will be for the Centers for Medicare & Medicaid Services to reverse its 2013 decision to not cover the scans, except for patients who are enrolled in clinical trials.

Dr. Maria Carrillo

Dr. Maria Carrillo

At that time, CMS agreed that amyloid imaging is useful for excluding Alzheimer’s in some clinically difficult diagnoses and that it is a very good tool for ensuring that amyloid-positive patients are actually being enrolled in studies. But, officials said, there is little extant evidence that being able to identify amyloid plaques in the brain of a cognitively impaired patient can do anything to alter the trajectory of illness, either clinically of financially. It’s never been linked to improvements in any clinical outcomes – either avoidance of expensive or futile testing, reduced hospitalizations, improved quality of life, or delay of disease progression. And since there are no disease-modifying therapies, amyloid imaging has never been proven to contribute to treatment decisions.

Referring physician eligibility

Participating physicians must be dementia specialists: trained and board certified in neurology, psychiatry, or geriatric medicine and devoting at least 25% of patient time to the evaluation and care of adults with acquired cognitive impairment or dementia. Each dementia specialist will be included in a contractual agreement with the American College of Radiology, which will ensure eligibility and facilitate payment for submitted data. Each referring physician’s practice will need to obtain approval of an Institutional Review Board to participate in the study. The IDEAS team has contracted with Schulman Associates to provide central Institutional Review Board (IRB) services, but local IRB approval is also acceptable.

Patient eligibility

Patients must have either mild cognitive impairment or dementia of unknown etiology, meeting the Alzheimer’s Association’s appropriate use criteria for amyloid imaging. They must undergo laboratory tests (complete blood count, comprehensive metabolic panel, thyroid function tests, and vitamin B12 level) and structural brain imaging (CT or MRI). Information about other diagnostic tests completed prior to referral (e.g., lumbar puncture; fluorodeoxyglucose, or FDG-PET) will be collected, but these tests are not required.

msullivan@frontlinemedcom.com

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