Clinical utility of amyloid PET in cognitively impaired patients

A nationwide study in the USA has found that amyloid PET significantly influences clinical management, including the use of medications and counselling, of patients with mild cognitive impairment (MCI) or dementia. Changes in management were observed in about 60% of cases, more than double what the researchers had expected.

The main findings on the Imaging Dementia – Evidence for Amyloid Scanning (IDEAS) study, were presented in a plenary session by Prof. Gil Rabinovici (University of California San Francisco, USA). “IDEAS was really a nationwide effort to get evidence for the clinical utility of amyloid PET in MCI”, he stated. This was requested by the national US health insurance program Medicare. Prof Rabinovici reported results regarding the study’s first aim, which was to investigate the impact of the scan on patient management.

At 595 clinical dementia sites, 11,409 Medicare beneficiaries with MCI (60.5%) or dementia (39.5%) were recruited. “This has been the only time in my career that recruitment was finished early and under budget”, Prof Rabinovici observed. “I think it reflects a desire by everyone involved to have amyloid PET covered by insurance.” A total of 18,295 scans were completed. The primary objective was to assess whether there was a ≥30% change in post-PET patient management in Alzheimer’s disease (AD) drug therapy; other relevant drug therapy; and counselling about safety and future planning.

The composite endpoint largely exceeded the target of 30%: it changed in 60.2% of patients with MCI and 63.5% of patients with dementia (P<0.001). The most common change involved AD medications: their use increased largely in patients with positive scans and decreased slightly, but still significantly, in patients with negative scans (P<0.001). The aetiologic diagnosis of AD was abandoned in 25.1% of participants, and was changed from non-AD to AD in 10.5%. There were also post-PET reductions in the use of neuropsychological testing, other brain imaging, and CSF studies. The second aim of the study is to investigate the impact of amyloid PET scans on health outcomes; analyses are underway.

Rabinovici G, et al. AAN 2019, Plen01.001.

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