Imbalance in reporting on Alzheimer’s PET scan research

Just two weeks ago, CBS reported on PET scans for Alzheimer’s disease, “New scan may diagnose Alzheimer’s as brain changes occur,” based on a study in the journal Neuron.  (Do they scour this journal all the time?)

Just four days ago, the Washington Post reported ongood news on Alzheimer’s: Better ways to diagnose it.”  Excerpt:

“Now, for example, we no longer have to rely on autopsies to confirm the existence of Alzheimer’s plaques. In a major advance last year, the Food and Drug Administration approved a method that uses a radioactive dye, known commercially as Amyvid, to light up amyloid plaques in a PET scan.”

University news releases promote even more Alzheimer’s PET scan research. For example, this UCLA news release: “Early imaging, diagnosis of Alzheimer’s leads to changes in patient care, better outcomes.”

Some journalists love such stories.  PET produces bright, colorful images.  It’s “good news” for Alzheimer’s, as the Washington Post headline stated, right?

Well, I didn’t see that either CBS or the Washington Post – or any other mainstream news organization, for that matter – reported on a paper published online this week by JAMA Internal Medicine – “Amyloid-? Positron Emission Tomography in the Diagnostic Evaluation of Alzheimer DiseaseSummary of Primary Findings and Conclusions.” The researchers reported that they analyzed data from 15 articles reporting on 15 studies focusing on Amyloid-? PET scan imaging. Their summary included this:

“At present, the medical literature provides extremely limited data with which to evaluate the clinical utility of A? (amyloid-?) PET. There are reasonable data showing that, when read by well-trained interpreters, A? PET is highly accurate in determining whether there is amyloid in the brain. However, the clinical utility of a positive scan result remains uncertain. If tested, approximately one-third of cognitively normal older adults would have a “positive” test result for brain amyloid. Thus a positive A? PET result is not diagnostic of AD, nor can the test be used to accurately predict the risk or the timing of progression of mild cognitive impairment.

The clinical utility of a negative A? PET result seems greater than the clinical utility of a positive result because the high sensitivity of a negative test result allows AD to be effectively ruled out as the cause of a patient’s cognitive impairment. It remains uncertain, however, if negative test results lead to important changes in subsequent clinical management or whether any such changes would produce net health benefits for patients and families. Even if negative test results would produce net benefits, rigorous evaluations of A? PET must consider the overall balance of benefits and harms of both positive and negative test results in broadly representative patient populations. The current literature on A? PET imaging for AD is insufficient to provide this level of evidence. Given the limited effectiveness of the targeted treatments for AD that are currently available, demonstrating that A? PET leads to changes in clinical impressions and intended management is insufficient. More persuasive evidence that A? PET improves patient outcomes is needed.”

An editor’s note in the journal stated:

“Clearly, more data are needed about the role of A? PET in the prevention, diagnosis, and treatment of patients with AD. At present, the evidence tells us that the role of the scans is uncertain in many situations. The test could aid diagnosis and management in some circumstances, but it could also be harmful in other circumstances; for example, if a positive scan result leads to labeling a person as having a dread and incurable disease and that potential diagnosis turns out to be wrong.”

Why wouldn’t this paper and this editorial receive the same kind of attention as the “good news” stories highlighted above?  Don’t journalists see the huge public policy issues at stake here?  It’s difficult to understand. If you’re that committed to reporting on imaging tests for Alzheimer’s that you are scouring the journal Neuron, for example, wouldn’t you consider these articles newsworthy as well?  If not, why not?


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Comments (1)

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Judy Graham

October 5, 2013 at 11:57 am

The information you cite here from JAMA Internal Medicine echoes that found in the Medicare coverage decision for amyloid PET scans just a few months ago.

As someone who reported on the Medicare coverage decision, I didn’t see anything new in the JAMA Internal Medicine report. But it is disappointing to see how many reporters handle this issue, uncritically accepting the notion that imaging results must enhance doctors ability to diagnose Alzheimer’s.