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WHO Publishes Preferred Product Characteristics for Alzheimer’s Blood Tests

The PPC outlines guidance for the development of blood tests for Alzheimer's, including important considerations to increase accessibility and diversity.

The World Health Organization (WHO) has published the preferred product characteristics (PPC) for blood-based diagnostic biomarkers for Alzheimer’s disease. This document sets out to guide those involved in the development of Alzheimer’s blood tests on methods for achieving optimal clinical performance as well as critical contextual considerations.

The PPC reaches out to institutions that would come to the WHO for policy guidance and prequalification. Those institutions could be funders, researchers, product developers, or regulatory agencies involved in the development and implementation of blood-based Alzheimer's tests.

As the global population ages, cases of dementia are estimated to become more frequent. Dementia is already a major cause of death and disability, with over 55 million people estimated to be living with the disease globally. The most common cause of dementia is Alzheimer’s disease, causing 60-70% cases.

In Alzheimer’s cases, it is important that the patient receives an accurate diagnosis at the right time to access the care they need.

Alzheimer's disease is currently diagnosed based on the judgement of clinicians, often with the aid of head imaging and biomarkers from patient cerebrospinal fluid. Long wait times and the strain on resources associated with the current methods has led to the development of simpler diagnostic methods like blood tests.

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Recently, scientists have turned to proteins found in the blood as early diagnostic biomarkers for Alzheimer's disease. These tests have the potential to predict onset of the disease earlier and more affordably while requiring fewer resources. It’s an attractive offering for healthcare systems in low- and middle-income countries (LIMCs) where there is a shortage of medical resources and qualified health professionals.

Recent efforts in the development of these blood biomarkers have been promising, but only within a limited and highly-resourced context.

The WHO points out that the clinical settings where such tests are being trialled have involved populations of limited diversity. It says that, in order to fully implement such products in the real world, validation is needed on a much wider and more diverse scale. Furthermore, the PPC says that this validation needs to consider the clinical contexts where the tests will be used, particularly in LMICs, noting an expected global increase in dementia in these areas.

In the interest of driving this diversity, the PPC outlines a range of characteristics that future diagnostic tools should consider during development.

The PPC specifies the factors that need to be considered when interpreting results from blood-based diagnostic tests. These include age, sex, genetic mutation, medications, comorbidities, local/regional conditions, and disease stage. Furthermore, accessibility, affordability, workforce capacity and training, requirements of technical support, and equipment maintenance are all noted as considerations.

Also mentioned in the PPC is the WHO’s global dementia action plan. This includes the importance of pairing diagnostic tools with increased access to post-diagnostic support, as well as the participation and empowerment of people with lived experience in the development process of such tests.

The WHO hopes that the PPC will encourage innovation and development of products for use in settings more relevant to the global unmet public health need.