Amyloid PET could help patients with dementia of unknown cause: a study now aims to clarify this

If PET can better distinguish between Alzheimer's disease and other forms of dementia, this might allow more precise drug administration and longer maintenance of independence.

In patients with dementia of unclear cause (aetiology), an additional amyloid PET diagnostic procedure might possibly be advantageous compared with a standard diagnostic procedure alone. The German Institute for Quality and Efficiency in Health Care (IQWiG) reached this conclusion after reviewing the documents of a manufacturer and conducting its own systematic search. PET can lead to medication changes that might result in better cognitive performance and fewer hospital stays. The method therefore has the potential to be a treatment alternative that should be reimbursed by the health insurance funds. In IQWiG's opinion, a testing study that is suited to obtain the necessary information for the assessment of the method’s benefit is basically possible.

According to the "testing regulation" (137e Social Code Book [SGB] V), the Federal Joint Committee (G-BA) can decide on directives for testing examination and treatment methods whose benefit has not yet been sufficiently proven, but that indicate "the potential of a necessary treatment alternative" – it can therefore initiate clinical trials to improve the evidence base for individual methods.

On behalf of the G-BA, IQWiG assessed whether amyloid PET offers such potential for a treatment alternative. After the Institute basically answered this question with "yes", the G-BA passed the "Guideline for testing amyloid positron emission tomography (PET) in dementia of unclear aetiology" on 6 February 2020. After the Federal Ministry of Health (BMG) did not raise any objections, the testing directive is now effective.

PET to distinguish between different forms of dementia

The diagnostic procedure PET is an imaging technique in which several slice images are taken of a body region. These images show the imaged region layer by layer, as in thin slices. This method uses a radioactive substance that is not considered to be harmful to humans at the dose used.

The aim of amyloid PET is to exclude or detect pathological protein deposits in the brain that are typical of patients with Alzheimer's disease. In the event of unclear dementia syndrome, the procedure should provide diagnostic information that can be used to adapt the management of treatment. For example, people with dementia who are currently taking drugs for Alzheimer's disease could, if the PET result contradicts this diagnosis, omit these drugs (and thus avoid their side effects).

IQWiG’s present assessment of potential is based on the results of the randomized controlled trial published in 2017 by Pontecorvo and colleagues, which showed that in patients with cognitive impairment, amyloid PET helps to identify the presumed cause of disease. The distinction between different forms and causes of dementia then led to adjustments in medication. It is to be hoped for, but not yet proven, that targeted medication leads to both better cognitive performance and fewer side effects. Both could help to avoid hospitalization and loss of independence in people with dementia. The study now commissioned by the Federal Joint Committee will focus on this question.

Further data on patient-relevant advantages necessary

Julia Kreis, Head of IQWiG’s Assessment of Potential Division, emphasizes: "In order to be able to draw a reliable conclusion on the benefit of amyloid PET in dementia of unclear aetiology, meaningful data on patient-relevant outcomes are required." For this reason, the G-BA has now initiated a testing study to investigate whether, following an amyloid PET, changes in diagnostic procedures and management in patients with dementia of unclear aetiology actually lead to advantages with regard to the course of dementia. Above all, advantages should be demonstrated in maintaining independence. Julia Kreis also notes: "It is good that with the Appointment Service and Health Care Act (TSVG) the legislator has removed a major hurdle for the planning and implementation of testing studies. The G-BA can now fund such studies itself. This eliminates the often time-consuming evaluation of the extent to which the manufacturers are to contribute appropriately to the costs. I hope that under the new conditions meaningful innovations will find their way more quickly into health care."

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