The IDEAS Study was developed in response to the 2013 Centers for Medicare & Medicaid Services (CMS) National Coverage Decision on amyloid PET imaging in dementia and neurodegenerative disease. CMS did not provide coverage for the scans stating “the evidence is insufficient to conclude that the use of positron emission tomography (PET) amyloid-beta (Aβ) imaging is reasonable and necessary for the diagnosis or treatment of illness or injury or to improve the functioning of … Medicare beneficiaries with dementia or neurodegenerative disease.”

CMS questioned the ability of PET amyloid imaging to lead to improved health outcomes, such as avoidance of futile treatment or tests, improving or slowing the decline of quality of life, and survival. However, CMS did find sufficient evidence that the use of PET Aβ imaging is promising: (1) to exclude Alzheimer’s in narrowly defined and clinically difficult diagnoses, and (2) to enrich clinical trials seeking better treatments or prevention strategies for Alzheimer’s. Under the National Coverage Decision, Medicare would provide coverage for one amyloid PET scan per patient enrolled in an approved clinical study.

Over the subsequent 18 months, the Alzheimer’s Association led an initiative to bring interested stakeholders together to develop a Coverage with Evidence Development program. The IDEAS Study team was formed from this larger group of stakeholders, and developed the protocol through an iterative process, soliciting feedback from a Scientific Advisory Board, an Industry Stakeholder group, and the CMS Coverage Analysis Group.

Amyloid PET imaging alone does not establish a diagnosis of Alzheimer’s disease, but the findings from such a test must be considered in the context of the person’s medical history, physical examination, and cognitive testing. To guide clinicians on how best to apply amyloid PET in the clinical evaluation of people with cognitive decline, a working group convened by the Alzheimer’s Association and the Society of Nuclear Medicine and Molecular Imaging (SNMMI) developed appropriate use criteria (AUC) for brain amyloid PET scans. The AUC represent the primary inclusion criteria for the IDEAS Study.

The AUC indicate that amyloid PET should only be considered in patients with clear, measurable cognitive deficits when there is substantial diagnostic uncertainty after a comprehensive evaluation by a dementia specialist. According to AUC, amyloid PET may have greatest value in patients with either: (1) progressive, unexplained mild cognitive impairment (MCI); or (2) dementia of uncertain cause due to atypical or mixed symptoms, or unusually early age-of-onset.

A total of approximately 18,488 Medicare beneficiaries age 65 and older meeting AUC were enrolled over 22 months at more than 600 sites throughout the United States. Study participants were recruited into one of two sub-groups: (1) progressive, unexplained MCI, and (2) dementia of uncertain cause.

The IDEAS Study design was approved by CMS in 2015. All referrals to the study and for amyloid PET came from dementia specialists, defined by the Alzheimer’s Association and SNMMI as “physicians trained and board-certified in neurology, psychiatry, or geriatric medicine who devote a substantial (≥ 25%) proportion of patient contact time to the evaluation and care of adults with acquired cognitive impairment or dementia, including probable or suspected Alzheimer’s disease.” Dementia specialists were recruited through societies such as the American Academy of Neurology plus clinician outreach through the Alzheimer’s Association and other advocacy groups, industry partners and news media outreach.