But what's the intention? If you do a scan and then try to find everything that is wrong about you, you're 100% right, there will be false positives and unnecessary panic/medication etc.
However if you just collect data for months and years and WHEN you get a symptom you have a lot more data then we should be able to give better diagnosis faster. If we do that for long enough as humanity and there is data sharing the accuracy of the whole thing will increase a lot.
Compare: The placebo effect works (at a reduced rate) even if you tell people they're getting a placebo!
By having a whole slew of test results already, you will have much better priors.
To your point though I think there is a difference between collecting and evaluating additional data sources and using them as diagnostic tools.
I suppose I fundamentally disagree with the implication of your post that there is no value in gathering further data for these reasons, it would seem to suggest we’re already diagnostically optimal and could not do better with additional signal.
> The downside, and the reason why most doctors do not recommend full body scans, is that every human body is a bit weird and there will almost always be something "wrong" that will be visible in a full body scan. This can lead to unnecessary testing, anxiety, and even unnecessary procedures. Many of these oddities flagged by the scan would never have caused any actual issues had the patient never been aware.
The fundamental problem is that you generally can't diagnose simply from shapes. Scans show shapes, shapes cause concern, concern leads to invasive procedures, results are negative.
Also, overdependency on "spas" for health information could lead to an atrophy of other sorts of medical information gathering and diagnosis. e.g., there's no mention in the dreamy description of this spa experience of getting a blood draw or a patellar reflex test.
You [hopefully] won't have to become a rare missed diagnosis because you didn't fit the demographic for this or that screening test.
Cost of genomic analysis is exponentially decreasing, and so much progress is happening so quickly.
Consider for example how in cardiology we advanced from ASCVD's 10-yr prognosis, to the PREVENT 30-yr prognosis. And still most providers are using the ASCVD score for their patients.
The chance a positive is real is so low you may as well just point to a body part and get it biopsied.
A positive from this kind of test is statistically meaningless.
If you let it give out tons of false positives, then patients are trained to ignore it when it cries wolf.
If you dial it back so that it gives out fewer positives, then now it starts giving out false negatives and not helping sick people.
Sadly, there's no perfect threshold when the signal and noise distributions overlap substantially, just different trade-offs.
(Love CI, btw!)
For example, single nucleotide polymorphisms. This way doctors spend less time guessing which medication is likely to work best for you when there are many options available.
I don't know about traditional blood testing, but a permanent implant which checks HR, pressure, glucose, temperature & oxidation would be pretty useful, not necessarily to diagnose anything, but to provide data for doctor when patient has actual symptomps.
https://www.rieti.go.jp/en/columns/a01_0455.html This japanese article found "No clear-cut evidence exists to determine whether undergoing health checks leads to greater longevity and/or lower medical expenditures."
https://pubmed.ncbi.nlm.nih.gov/31642821/
And blood pressure is especially pernicious, basically every doctors office measures it wrong so the results aren’t particularly useful. Many use the wrong size cuff for example, or don’t give people time to relax before a reading. A ton of people have white coat hypertension, high BP only because they’re in a doctors office.
https://pmc.ncbi.nlm.nih.gov/articles/PMC1120072/
I saw a paper that showed only 36% of cardiologists did it right.
And then, even that's not enough. Decision theory needs to be applied to decide what action to take. That means taking into account the expected QALYs, cost and inconvenience across the distribution of possible outcomes. There's a whole spectrum of possible decisions, from immediately performing surgery, performing an invasive test like a biopsy, performing other less invasive tests, scheduling a follow-up non-invasive test at a later date, or just following a regular schedule of non-invasive tests and looking for any evolution along a longer time period.
The real problem is the binary thinking of either "we think you have X" and therefore tests must be performed or "we think you don't have X" and therefore tests shouldn't be performed. If medical organizations adopted empirically grounded decision frameworks, by applying them consistently doctors would be able to see something anomalous, assess that the risk isn't high enough to warrant immediate investigation, and be protected from a lawsuit in the unlikely case it was, in fact, something. And then we could do away with this "if we look we might find something" nonsense, which is pure fallacy.
But what you can do then, is either run a more expensive, elaborate test or one that's proven to be statistically independent on the positive testing population.
FPR can even be a good thing. Let's say you have an expensive test with a very low false positive rate. Then you can mix together 100 samples, and get a test with a much worse FPR 100 times cheaper. Then you can repeat the same individually on the positive population.
This is fully automatic and you don't even think about it. Btw, this is why mass testing, and public healthcare can be better. You can amortize the cost of things across a large number of people for no disadvantage.
Problem is we never know who is healthy. That is why we are doing the test.
If you mean run different tests, where you collect different kinds of data from the same individual, sure but that's not something you can "just do" in the general case.
It's news to no one that tests are imperfect.
Do you have any concrete solution to that? Anything of value?
Diabetes is asymptomatic for years and is prevalent in every demographic. Leaving it unattended it can cause damage to blood vessels, nerves, kidneys, and eyes through chronic high blood sugar, by which time complications may be advanced; detecting it on time can prevent or delay this with treatment and lifestyle changes.
Hyperlipidemia is asymptomatic for years and is prevalent in every demographic. Leaving it unattended it can cause artery blockage through cholesterol buildup, by which time heart attack or stroke may occur; detecting it on time can prevent this with diet and medication.
Kidney disease is asymptomatic for years and is prevalent in every demographic. Leaving it unattended it can cause kidney failure through gradual loss of function, by which time dialysis may be needed; detecting it on time can slow progression.
Glaucoma is asymptomatic for years and is prevalent in every demographic. Leaving it unattended it can cause irreversible vision loss through optic nerve damage, by which time blindness may be permanent; detecting it on time can preserve vision.
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I'm SO glad you're not my family doctor!
On the other end of the spectrum, what doesn’t make sense is testing a random person off the street for Ebola. The prevalence approaches zero and symptoms are fairly noticeable, so any positive test is definitely wrong.
Most diseases are in between and have to be evaluated case by case, not buckshot.
You may be particularly interested to hear that there’s little evidence to support regular checkups in most adults beyond blood pressure testing and cervical cytology.
> Given the lack of favorable evidence and the potential adverse effect, primary care providers should consider the fact that general health checks, beyond the screening interventions shown to have benefit, likely have little or no effect on important health outcomes. Some of the interventions with demonstrated benefit have sufficiently large effects that a uniform application is warranted (blood pressure measurement and cervical cytology screening). In others, the trade‑off between benefits and harms is so close that patients should be involved in fully shared decision making regarding their participation (breast and colon cancer screening).
https://pubmed.ncbi.nlm.nih.gov/31642821/
I suspect your doctor would agree with me. See if they’ll test you for Ebola, for instance. Not because you have symptoms but just cuz.
In your list, 1-4 are common enough, the tests are accurate enough, the costs of intervention are low enough and the benefits of early intervention are high enough to justify screening, which is why they do generally screen for them at least in hgiher risk groups. The other two are more mixed, which is why mass screening is less common.
All the evidence for full body scans is that they are not justified for asymptomatic people. The false positives are high, the costs of these false positives are high, and the imporved outcomes are too low to justify them. If you want one, go ahead, but realise that almost anything it finds is likely to be false either positive or not likely to ever cause a problem, and you'd have to deal with the worry and invasive tests and even surgery in aid of something that may never cause any trouble.