Positron emission tomography (PET) that detects amyloid-β plaques, a feature of Alzheimer disease, is useful in the diagnostic assessment and management of patients with mild cognitive impairment (MCI) or dementia of unknown etiology, according to a study published in JAMA.

This single-group, longitudinal study (ClinicalTrials.gov identifier: NCT02420756) included 11,409 Medicare beneficiaries who had MCI (n=6905) or dementia (n=4504) of uncertain or unknown etiology, and for whom a diagnosis of Alzheimer disease was being considered. Knowledge of PET results was expected to change the diagnosis or management approach, in which 946 dementia specialists at 595 US sites documented the participants’ diagnoses and management plans before PET and 90 (±30) days after PET.

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The primary end point was the composite change in management approach between pre- and post-PET visits defined as starting, stopping, or modifying certain elements of treatment, including Alzheimer disease drug therapy, other drug therapy, or counseling about safety and future planning. A secondary end point was a change in diagnosis from Alzheimer disease to non-Alzheimer disease and vice versa.

Positive amyloid PET results were found in 55.3% of patients with MCI and in 70.1% of patients with dementia. A significant change in the composite management end point was reported by 60.2% (95% CI, 59.1%-61.4%) of participants with MCI and 63.5% (95% CI, 62.1%-64.9%) of participants with dementia (P <.001, 1-sided for each group). The etiologic diagnosis changed from Alzheimer disease to non-Alzheimer disease in 25.1% (95% CI, 24.3%-25.9%) of the participants, and from non-Alzheimer disease to Alzheimer disease in 10.5% (95% CI, 10.0%-11.1%) of the participants.

Limitations to the study included the lack of a control group and a nonrandomized study design; however, the results were consistent with other reports attributing changes in clinical management and even met a higher prespecified threshold rate. The study did not compare amyloid PET with other diagnostic tools associated with changes in clinical management. Finally, the population lacked the racial and ethnic diversity of Medicare beneficiaries or the overall US population, limiting the generalizability of findings.

The investigators suggest that the core elements of a patient’s management plan changed after amyloid PET, in which participants with MCI and dementia of uncertain etiology were associated with clinical management changes within 90 days of PET. They suggest future research should evaluate the association of amyloid PET with improved clinical outcomes.

Disclosure: Multiple authors declare affiliations with the pharmaceutical industry. Please refer to reference for a complete list of authors’ disclosures.

Reference

Rabinovici GD, Gatsonis C, Apgar C, et al. Association of amyloid positron emission tomography with subsequent change in clinical management among Medicare beneficiaries with mild cognitive impairment or dementia. JAMA. 2019;321(13):1286-1294.