Alzheimer – Overdiagnosis, Overtreatment, and Surrogate Endpoints

Thomas Falasca, physician and author of Physician’s Guide to Better Medical Decision Making: Critical Thinking in Medicine

Praise to Kenneth Langa and James Burke for their insightful article “Preclinical Alzheimer Disease—Early Diagnosis or Overdiagnosis?” in JAMA Internal Medicine, July 8, 2019. 

The authors draw attention to current clinical trials testing monoclonal antibody treatments (eg, solanezumab) aimed at decreasing the build-up of amyloid protein plaques in the brains of adults with preclinical Alzheimer disease as assessed with neuroimaging and biomarker technologies.

However, they emphasize, these technologies could identify as preclinical Alzheimer 30% of the US population over 50-years-old, whereas only 31% of women and 23% of men thus identified are estimated to eventually exhibit dementia, a clear example of overdiagnosis.

Further, clinical trials may not use dementia as the primary endpoint, but rather the surrogate endpoint such as a change in cognitive scores over a given time period, certainly not a guarantee of delaying or preventing dementia.

Finally, the consequent overtreatmentof pre-Alzheimer, potentially including PET scans, IV infusions, biologicals, and cholinesterase inhibitors would be associated with its own harms and misallocation of resources. 

It is time to tread cautiously and give this potential problem of overdiagnosis the respect it warrants.

 

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