[tptacek]

* Doctors and medical researchers keep saying that routine MRIs for non-symptomatic or low-risk patients is a bad idea, because the outcomes are worse than not scanning.

* There's several clear, understandable mechanistic reasons why this would be the case, including simple applications of the base rate fallacy.

* Nevertheless, here we are, nerds arguing we know better than all these people.

[cyberax]

And I don't buy that. EXACTLY this was also said about prostate cancer screening. Word-for-word. "Overdiagnosing", "people are better off not knowing", "psychological burdens", "invasive procedures", etc.

Now we have multiple longitudinal studies of people receiving aggressive screening and the usual standard of care. The aggressive screening group, unsurprisingly, has better outcomes with less mortality.

> * There's several clear, understandable mechanistic reasons why this would be the case, including simple applications of the base rate fallacy.

Yeah. I guess it's time to stop using fire alarms. People are better off not knowing if a building is on fire, and frequent false alarms have a negative effect on psychological well-being.

Just look at the risk of burning to death. Alarms make no sense at all!

> * Nevertheless, here we are, nerds arguing we know better than all these people.

Yes. Absolutely. And I actually have read (I think) all the studies, and came thoroughly unimpressed. They're utterly sloppy with poor statistical analyses.

It's absolutely an indictment of the medical industry that has become so crusty that it can't be bothered to integrate new diagnostic modality. That is the _only_ way to detect multiple lethal cancers while they are still curable.

[tptacek]

You're not engaging with the logic. Stipulate that it is the only way to detect multiple lethal cancers. If you end up harming more people than you help, the intervention is bad. Right now, you're only looking at one half of the balance sheet.

[cyberax]

> You're not engaging with the logic.

Ditto for you.

> Stipulate that it is the only way to detect multiple lethal cancers.

This is trivially true.

> If you end up harming more people than you help, the intervention is bad.

The only pathway through which diagnostic MRIs can feasibly harm people is aggressive follow-up of uncertain findings. And this is almost completely solved by just doing another scan several weeks/months in the future. With corresponding patient education.

This is literally all what was needed in the case of prostate cancer screening: less aggressive biopsies and bias towards observation rather than action. Yet it took _two_ _decades_ to arrive at this point. And some doctors _still_ refuse to order screening tests out of this misplaced idea of "not knowing is better".

And this is not the only time when "geeks knew better". For example, checklists for surgeries are a no-brainer to anyone with an aviation background. Yet they became standard only two decades ago ( https://pmc.ncbi.nlm.nih.gov/articles/PMC6032919/ )! Over rather strong objections from doctors.

[tptacek]

The people arguing against routine MRI scans are the checklist people!

But, look: if you think routine prostate screening is a good idea, I don't have a counterargument. You're right: there's already an emerging discipline of watchful waiting with prostate pathologies.

The argument being made here is about full body MRI scans: doing a dragnet sweep looking for neoplasms anywhere and everywhere. Not the same thing! Similarly: my belief that the EBM people are right about full-body scans doesn't mean I oppose colon cancer screening!

[cyberax]

> The people arguing against routine MRI scans are the checklist people!

Are they? They seem to be exactly the same set of people who resisted them ( https://pubmed.ncbi.nlm.nih.gov/22069112/ ).

> The argument being made here is about full body MRI scans: doing a dragnet sweep looking for neoplasms anywhere and everywhere. Not the same thing!

It's exactly the same thing, but on a larger scale. Yes, it will likely require at least some adjustment to the standards of care and development of more stringent criteria for follow-up procedures. But we're already talking about fine-tuning, rather than something fundamental.

Here's a study from one of the providers:

> Prenuvo's recent Polaris Study followed 1,011 patients for at least one year following a whole-body MRI scan. Of these patients, 41 had biopsies. More than half of the 41 were diagnosed with cancer. Of these cancers, 68% didn't have targeted screening tests and 64% were localized when detected. The company says it finds possibly life-threatening conditions in 1 in 20 people.

So we're talking about the real-world 4% rate for biopsies, with about 50% false positive rate. This is not that far removed from the current clinical 30% false positive rate. And this is far from the apocalyptic scenarios of multiple biopsies for every patient.

And the psychological burden appears to be modest: https://pubmed.ncbi.nlm.nih.gov/33279799/

While the negatives cited by doctors are:

> To date, no study has been performed that rigorously investigates the impact on disease-specific survival following whole body MRI in asymptomatic patients without specific risk factors, and no study has been performed to confirm that a ‘negative’ whole body MRI excludes significant disease 5 or more years’ later.

I read most of the studies that are cited here: https://www.ranzcr.com/college/document-library/2024-positio... And I have not found a single one that had anything really negative about the MRI consequences. And half of them are outright positive endorsements: https://pubmed.ncbi.nlm.nih.gov/33216779/

The only real remaining argument is cost effectiveness of MRI, especially for government-based healthcare. It is a valid argument, but it's beside the point for people who are self-paying. And it's also missing the implications of economy of scale.

So I'm pretty sure in this particular case the geeks indeed know more than doctors.