11 ms·

We Don’t Need More Blood Tests

110 points by fisherjeff 10y ago

pidge 10y ago
Think about it as getting a time series of previous measurements to aid in the detection of anomilies. If you just give me the metrics of a production system at an instant in time, it's hard to say whether anything's wrong. But when I know the response time has been in the same range for the past year, and then increases to 2x and stays that way for a week, I can be pretty confident that something broke. Whether we're anywhere near feasibly getting that resolution of data is a different question.
ssivark 10y ago
Abstracting out the essence of this article: It's arguing about the danger of ubiquitous "big data" in certain contexts. The human population around 8 billion, which is 2^33. 33 is roughly the number of pairs out of 9 objects. Heuristically, this would mean that if we test for more than 9 boolean variables (high/low), purely by randomness we will start seeing correlations due to a "limited" population size of 8 billion. If we start treating people just based on those observations, we would seriously wreck human health. Diagnosis (decision making) based on correlations (rather than causality) is very tricky.
- harigov 10y ago
  For the record, we _are_ treating people based on exact same observations albeit correlated on much less number of people. However, we make use of some probability, other observational and subjective evidence in order to determine right course of action. I agree with another comment made above regarding "less data is never the answer". We may make some mistakes with small amount of data but the only way we will ever learn is by making a hypotheses and acting on it. We should tread carefully but not too careful to never step forward.
melling 10y ago
The argument is that some blood tests aren't that effective and you get false positives. For certain tests that might be true. However, aren't we still better off if we can perform all tests more cheaply and on a more regular basis? Having a few tests that aren't effective does not invalidate the entire goal.
- blakesterz 10y ago
  That's exactly what I was thinking. Sure, if we look at a population then maybe we don't see a remarkable result. But surely we've helped SOMEONE here. From the article: "which means that only 27% of positive test results are right" Yes, 27% is not great, but that's still more than 1/4 of the people that had a good result and will live longer or better or whatever. 1/4 of the people got some kind of benefit. Sure, we'd rather see 75% but 27% is SOMETHING and that's worth, well, something I guess. Does the cost mean it's worth it? For those in the 27% they are sure as heck going to say yes, right?
  - brianwawok 10y ago
    Maybe, maybe not. For example the treatments for prostate cancer can be worse than not treating early state elevated PSAs. Being told you have AIDs, then 24h later being told "just kidding false positive"... do you think that has no consequences on your life?
    - amelius 10y ago
      > For example the treatments for prostate cancer can be worse than not treating early state elevated PSAs. I suppose that positive test results need not be followed directly by treatment, but can also be used to trigger further testing.
      - brianwawok 10y ago
        In the specific case of prostate testing, all they can do is repeat the test. And it likely comes back with the same results. Many men in their 40s and 50s have high test results. Those same men can live 30, 40 more years with the condition. Or they can die of prostate cancer in 3 years. Or they could get treatment, and lose all use of their prostate for the rest of their life. It seems like prostate cancer testing is the poster child for "the test tells you something, but often you statistically don't want to act on the test...". I have no plans of ever having the test done.
  - pak 10y ago
jimrandomh 10y ago
I strongly disagree. We need more blood tests, and we need them badly. We need them in forms which people can self administer, outside of the prescription-and-professional-blood-draw model. The history of blood glucose testing is informative here. It used to be a hospital lab test, like most other tests: done fasting, infrequently, to diagnose diabetes. Today, that test is done with an over-the-counter test kit, and diabetics do it multiple times per day. This provides information that the infrequent, hospital version couldn't provide at all: how blood glucose responds to meals. There are many other tests which, if they could be frequent and self-administered, would enable people to make new discoveries. The common metabolic tests, for example - HDL, LDL, etc - are very closely analogous to glucose tests, in that they respond to meals and that response is probably more informative than the fasting test. But there's nothing analogous to a glucose tolerance test for cholesterol, because that requires ten tests in a row and that's too expensive. One of the more common complaints I hear from friends is about migraines. Blood tests are worthless there because it's impossible to get a blood draw during an actual migraine. Same for most mental illnesses; comparing blood tests between a bipolar person's manic and depressive phases would be fascinating, but no one does it. And that's not even mentioning micronutrient status screening. The rates of micronutrient deficiencies in the United States found by the National Health and Nutrition Examination Survey (NHANES) are shocking; it's the twenty-first century and the rate of iodine deficiency is 9%.
- brianwawok 10y ago
  You aren't giving false positives any credit. False positives can be DEVASTATING. If a test has 50, 75, 90% false positive rates, as many do - you are causing much panic for nothing. If tests were 100% reliable and a simple pinprick.. absolutely, everyone should take one when they wake up and drink their morning coffee. But with the accuracy of tests today? Not so sure. basically take any 100% healthy person. Run 500 tests on them. They will have 5-6 major problems via a false positive result. Run more detailed invasive tests on those. Maybe you rule them out, maybe you get another false positive. You could end up going through Chemo or some other "cure" for a disease you never had, and the "cure" could end up giving you real cancer.
  - 10y ago
bigchewy 10y ago
For those who haven't had a chance to read about the negative impact of testing, check out Atul Gawande's Overkill - http://www.newyorker.com/magazine/2015/05/11/overkill-atul-gawande http://www.newyorker.com/magazine/2015/05/11/overkill-atul-g... It explains why one of the most dangerous things for a healthy person to do is get tested. I've been in healthcare analytics for almost a decade now and see the same thing in the population data. Theranos and other pro-testers are usually well intentioned but fundamentally misguided and haven't looked at population wide data sets, which tell a different story.
- grandalf 10y ago
  What Gawande describes is more of a sysematic irrationality in the healthcare system than a flaw with a test. The decision to over-treat is part of the tradeoff we get when physicians are viewed as authority figures. Their inaction (not doing a treatment) is viewed as a delegitimization of the patient's needs, and so there is social pressure to treat, even when harm could be caused. This is a psychological blind spot that equally effects patient and physician. But with respect to tests, so long as a test has a known false positive and false negative rate, its result can be accurately factored into a probabilistic model of a patient's overall health. Our healthcare system is biased toward acute conditions and extreme interventions. Things like early disease progression and wellness are generally not even considered relevant to most doctors. The reasoning approach of an evidence-based differential diagnosis which is taught to medical students is a powerful heuristic, but it is designed to work within the constraints of acute illness and (potentially) urgent intervention. So of course if fails when test results are considered without appropriate measures to improve the signal to noise ratio of the first branch of the decision tree. With any kind of broad-spectrum, speculative testing, any result would need to be considered over time and in the context of many other factors. It is not a drop-in replacement for any step of the traditional differential.
  - cortesoft 10y ago
    "But with respect to tests, so long as a test has a known false positive and false negative rate, its result can be accurately factored into a probabilistic model of a patient's overall health." In order to do that, you would also need to know the correlations BETWEEN tests in terms of false positive and negative. And there are a lot of combinations.
Floegipoky 10y ago
It seems like one of the biggest issues here is that a single test for a given thing isn't enough data to be able to reliably tell whether or not the results are significant. So people are arguing that we should collect fewer data points? I totally disagree with this viewpoint. The medical community's current approach to testing (positive result, treat ALL THE THINGS!) is an artifact of the difficulty and cost of performing the tests; the inability of many providers to apply basic concepts of probability to test results should not be used as an argument against advancing the state of the art, particularly as the industry begins baking data-driven clinical decision support into automated health systems. If you have 40 tests spanning 20 years saying that you aren't at risk for Total Scrotal Implosion, and then suddenly, without any symptoms, you get a result saying your testicles will fall off tomorrow, you have context with which to interpret this result. Without the historic data there is much greater risk of you and your healthcare provider agreeing to an unnecessary knee-jerk scrotalectomy. Less data is never the answer. Just my 2 cents.
- specialist 10y ago
  I definitely wish I had a comprehensive log of tests over my lifetime. I'm now more interested in the changes (trends) than the absolute values.
- chuckcode 10y ago
  Completely agree. False positives are a fact of statistics, what we need is more data to establish baselines for people and populations and understand when is the right time to worry. I'm genuinely surprised that doctors aren't leading a charge to get more data about their patients and arguing instead for less testing and data. Do they really feel that their diagnostics are so good that they only need a few data points every couple years? My watch and phone know more about my health than my doctor.
  - grey413 10y ago
    It's been addressed elsewhere in the thread, but the problem is not statistical false positives, but rather technically "true" positives (for what the test measures) that do not correlate to an actual disease. More data points do not help.
amelius 10y ago
> which means that only 27% of positive test results are right The negative test results are still right 99.8% of the time.
- pessimizer 10y ago
  But throwing the blood sample in the trash and just saying "You don't have it" is right 98% of the time. Would you support that test? Because I'm willing to charge you for it.
chuckcode 10y ago
Pretty disappointed with 538 on this article. The basic argument is that we shouldn't do more medical testing as doctors aren't sure how to interpret the results, public isn't sophisticated enough to understand and too lazy to do anything even if they did. Personally I feel that if we had more data over a larger group of people we would be able to learn what leads to disease better. Further I'm a little shocked that the medical industry can get away with a stated policy that patients should wait until their symptoms are acute and then get a minimum number of tests so their doctors don't get confused. I'd like to see us have more data about our health even if we're not sure what to do about it right away. Ignorance is easier to implement but isn't always bliss.
- nemothekid 10y ago
  >Personally I feel that if we had more data over a larger group of people we would be able to learn what leads to disease better. The article is pretty much arguing that there isn't currently a method that exists that will accurately give us more data. How useful is "more data" when 73% of it is garbage?
- TeMPOraL 10y ago
  > Further I'm a little shocked that the medical industry can get away with a stated policy that patients should wait until their symptoms are acute and then get a minimum number of tests so their doctors don't get confused. It's because this is a reasonable strategy, that takes into the account the actual quality of the tests, the base rate, and the fact that people are idiots^W^Woverreact dramatically when it comes to health. This is a combination of insight that most of the serious diseases are rare, so most patients will be fine if they wait a little bit more, coupled with the insight that they most definitely won't be fine if they freak out, and most of them will.
deleted 10y ago
[deleted]
lordnacho 10y ago
Something is not clear to me. How do you know that a false positive is, in fact, a false positive? I presume there are some other pieces of information that provide the reference value. So when someone gets a positive test, why not put them through the next test to see if they keep coming up positive? What's the argument for not testing in the first place? It will panic people? If that's the case, why not make it random whether you're called to an extra test?
- DanBC 10y ago
  > Something is not clear to me. How do you know that a false positive is, in fact, a false positive? Bob has a full body MRI. THat returns some shadowy spots on his lungs. He's asked if he used to smoke (he did), and if he had any childhood illnesses (german measles, measles, chicken pox, etc) (he did). Are those spots early cancer? Or are they just scarring from the childhood illness? One way is to cut Bob open and have a look. Or jab him with a massive biopsy needle. Except, now you know that this one spot isn't cancer, it was a scar. How about all the rest? That one biopsy increased Bob's risk of harm. > What's the argument for not testing in the first place? Testing often doesn't give any useful information. It often gives wrong information - people who have a disease are told they don't have it, and people who don't have it are told they do have it. Many of these people then go on to have treatment. All treatment carries some risk of harm. You need to know if the benefits of testing (especially of testing a large, mostly healthy population) outweigh the risks of providing risky treatment to those people, some of who will not have the disease. You also have to see what happens if you just don't do anything. Prostate cancer is a good example here. Some people will die of it - they have an aggressive cancer that will kill them rapidly. But many people will die with it - they have a slow growing tumour, and they'll die in old age from something else. Treatment for prostate cancer is pretty harsh.
- Jtsummers 10y ago
  > What's the argument for not testing in the first place? The wider the pool of people being tested, the greater the chance of false positives, which is why screening guidelines generally limit the population to be screened. The more independent tests you do at once, each with its own chance of error, the larger the chance that at least one of those tests produces an incorrect result, said Rebecca Goldin, director of STATS.org and a professor of mathematical sciences at George Mason University. It's not just panic, but that if the false positive rate is too high then untargeted testing becomes overwhelming and counterproductive. There's a slim, very slim, chance that as a man I could develop breast cancer. But there's little value in testing me as it's not present in my family history (male or female). So let's say (in this example) that the false positive rate is only 1% in men and the true incidence rate is 0.01%, and we test 100 million men: 10,000 men have breast cancer, great we've detected it 999,900 men don't, but are subjected to more testing That more testing is likely costly, time consuming, and potentially invasive. This acts as a net drain on medical resources because we've just performed nearly 1 million unnecessary mammograms. They take technician and physician time. They take machine time. And so on. So false positive rates may be low, but when applied to a massive population the total number of false positives can overwhelm the system.
bane 10y ago
Yeah sure, but you know...what about disruption!
tokenadult 10y ago
A lot of the comments here reveal not having read the fine article (which is not very long). If you look at the graphic labeled "How Accurate Tests Can Be Mostly Wrong," about halfway down the displayed Web article, you will see a very carefully worked out (and realistic) example about how even a very accurate medical test can result in mostly false positive indications of a disease--all that is necessary for that, mathematically, is that there is a low base rate of the disease. Examples like this have been commonplace in books about statistical reasoning for making medical decisions for more than a decade, and I have shared links to Hacker News before that make this same point. This is something everyone needs to know (but the investors in Theranos didn't know) to make sound decisions about how much testing to do and what to do with test results. Other authors who write about this issue are cited in the article kindly submitted for our discussion. I urge everyone here to read a lot of the writings of Dr. John P.A. Ioannidis,[1] who is quoted in the article. [1] https://med.stanford.edu/profiles/john-ioannidis?tab=publications https://med.stanford.edu/profiles/john-ioannidis?tab=publica...
nommm-nommm 10y ago
See also Science Based Medicine - a skeptical look at screening tests. https://www.sciencebasedmedicine.org/a-skeptical-look-at-screening-tests/ https://www.sciencebasedmedicine.org/a-skeptical-look-at-scr...
erikb 10y ago
I have very high chance of diabetes and other blood sugar related health problems, like heart diseases. I certainly think that cheap, repetitive blood tests would help me improve my health in the same way having my phone count my steps helps me to have a more active life. Please make it work. Maybe that start-up won't make, then please make another one. Thanks.
jerryhuang100 10y ago
the article and most comments here are more about EH's VISION of empowering regular people for cheap and on-demand blood tests. but the major problems the regulatory bodies, medical practioners and diagnostics experts have are mostly about theranos' underlining TECHNOLOGY, its basic SCIENCES and daily lab PRACTICES. to this date none of these three has been established at theranos (non-peer-reviewed, non-core patents, criticized by cms & fda w/ banning threats). in short, it just does not work (yet?) it's like someone always talk about building beautiful resorts or gigatic mining operations on Mars, but fails to develop rocket propulsion systems or space travelling vehicles. if there would be other someone to bring us to Mars, it must be elon musk.
jrapdx3 10y ago
After decades of practicing medicine and seeing results of countless lab tests, I tend to agree with many of the comments here. The article isn't wrong at its core, but it is sensationalizing some very important issues. The idea that lab studies yield false positives (and negatives too) is hardly novel. Of course test results can be misleading or easily misconstrued. We know a single test, or even a set of tests is rarely definitive. We know interpreting tests is an exercise in probabilistic thinking and careful practitioners rely on test results only to the extent warranted. I often get a question like "so what does this test mean?" A single anomalous reading, probably not much. I answer "it's only a test", confirming a diagnosis is a laborious process to make sure the facts align as best as can be determined. That is, the gamut of history, direct observation, and a variety of lab/imaging measurements looking at a clinical situation from several angles need to converge. In many practice domains lab/measurement technologies provide tremendous benefit. Think about the contributions of imaging (CT, MRI), endoscopy (colonoscopy, etc.), and yes, advances in medical laboratory science also save untold lives every day. Everyone here on HN knows all technologies can and will be misused but that doesn't mean they are not valuable and worthy. I take my own advice to never forget: "it's only a test", and any test is no more useful than the limits of its credibility.

110 points by fisherjeff 10y ago

pidge 10y ago

Think about it as getting a time series of previous measurements to aid in the detection of anomilies. If you just give me the metrics of a production system at an instant in time, it's hard to say whether anything's wrong. But when I know the response time has been in the same range for the past year, and then increases to 2x and stays that way for a week, I can be pretty confident that something broke. Whether we're anywhere near feasibly getting that resolution of data is a different question.

ssivark 10y ago

Abstracting out the essence of this article: It's arguing about the danger of ubiquitous "big data" in certain contexts. The human population around 8 billion, which is 2^33. 33 is roughly the number of pairs out of 9 objects. Heuristically, this would mean that if we test for more than 9 boolean variables (high/low), purely by randomness we will start seeing correlations due to a "limited" population size of 8 billion. If we start treating people just based on those observations, we would seriously wreck human health. Diagnosis (decision making) based on correlations (rather than causality) is very tricky.

harigov 10y ago
For the record, we _are_ treating people based on exact same observations albeit correlated on much less number of people. However, we make use of some probability, other observational and subjective evidence in order to determine right course of action. I agree with another comment made above regarding "less data is never the answer". We may make some mistakes with small amount of data but the only way we will ever learn is by making a hypotheses and acting on it. We should tread carefully but not too careful to never step forward.

melling 10y ago

The argument is that some blood tests aren't that effective and you get false positives. For certain tests that might be true. However, aren't we still better off if we can perform all tests more cheaply and on a more regular basis? Having a few tests that aren't effective does not invalidate the entire goal.

blakesterz 10y ago
That's exactly what I was thinking. Sure, if we look at a population then maybe we don't see a remarkable result. But surely we've helped SOMEONE here. From the article: "which means that only 27% of positive test results are right" Yes, 27% is not great, but that's still more than 1/4 of the people that had a good result and will live longer or better or whatever. 1/4 of the people got some kind of benefit. Sure, we'd rather see 75% but 27% is SOMETHING and that's worth, well, something I guess. Does the cost mean it's worth it? For those in the 27% they are sure as heck going to say yes, right?
- brianwawok 10y ago
  Maybe, maybe not. For example the treatments for prostate cancer can be worse than not treating early state elevated PSAs. Being told you have AIDs, then 24h later being told "just kidding false positive"... do you think that has no consequences on your life?
  - amelius 10y ago
    > For example the treatments for prostate cancer can be worse than not treating early state elevated PSAs. I suppose that positive test results need not be followed directly by treatment, but can also be used to trigger further testing.
    - brianwawok 10y ago
      In the specific case of prostate testing, all they can do is repeat the test. And it likely comes back with the same results. Many men in their 40s and 50s have high test results. Those same men can live 30, 40 more years with the condition. Or they can die of prostate cancer in 3 years. Or they could get treatment, and lose all use of their prostate for the rest of their life. It seems like prostate cancer testing is the poster child for "the test tells you something, but often you statistically don't want to act on the test...". I have no plans of ever having the test done.
- pak 10y ago

jimrandomh 10y ago

I strongly disagree. We need more blood tests, and we need them badly. We need them in forms which people can self administer, outside of the prescription-and-professional-blood-draw model. The history of blood glucose testing is informative here. It used to be a hospital lab test, like most other tests: done fasting, infrequently, to diagnose diabetes. Today, that test is done with an over-the-counter test kit, and diabetics do it multiple times per day. This provides information that the infrequent, hospital version couldn't provide at all: how blood glucose responds to meals. There are many other tests which, if they could be frequent and self-administered, would enable people to make new discoveries. The common metabolic tests, for example - HDL, LDL, etc - are very closely analogous to glucose tests, in that they respond to meals and that response is probably more informative than the fasting test. But there's nothing analogous to a glucose tolerance test for cholesterol, because that requires ten tests in a row and that's too expensive. One of the more common complaints I hear from friends is about migraines. Blood tests are worthless there because it's impossible to get a blood draw during an actual migraine. Same for most mental illnesses; comparing blood tests between a bipolar person's manic and depressive phases would be fascinating, but no one does it. And that's not even mentioning micronutrient status screening. The rates of micronutrient deficiencies in the United States found by the National Health and Nutrition Examination Survey (NHANES) are shocking; it's the twenty-first century and the rate of iodine deficiency is 9%.

brianwawok 10y ago
You aren't giving false positives any credit. False positives can be DEVASTATING. If a test has 50, 75, 90% false positive rates, as many do - you are causing much panic for nothing. If tests were 100% reliable and a simple pinprick.. absolutely, everyone should take one when they wake up and drink their morning coffee. But with the accuracy of tests today? Not so sure. basically take any 100% healthy person. Run 500 tests on them. They will have 5-6 major problems via a false positive result. Run more detailed invasive tests on those. Maybe you rule them out, maybe you get another false positive. You could end up going through Chemo or some other "cure" for a disease you never had, and the "cure" could end up giving you real cancer.
- 10y ago

bigchewy 10y ago

For those who haven't had a chance to read about the negative impact of testing, check out Atul Gawande's Overkill - http://www.newyorker.com/magazine/2015/05/11/overkill-atul-gawande http://www.newyorker.com/magazine/2015/05/11/overkill-atul-g... It explains why one of the most dangerous things for a healthy person to do is get tested. I've been in healthcare analytics for almost a decade now and see the same thing in the population data. Theranos and other pro-testers are usually well intentioned but fundamentally misguided and haven't looked at population wide data sets, which tell a different story.

grandalf 10y ago
What Gawande describes is more of a sysematic irrationality in the healthcare system than a flaw with a test. The decision to over-treat is part of the tradeoff we get when physicians are viewed as authority figures. Their inaction (not doing a treatment) is viewed as a delegitimization of the patient's needs, and so there is social pressure to treat, even when harm could be caused. This is a psychological blind spot that equally effects patient and physician. But with respect to tests, so long as a test has a known false positive and false negative rate, its result can be accurately factored into a probabilistic model of a patient's overall health. Our healthcare system is biased toward acute conditions and extreme interventions. Things like early disease progression and wellness are generally not even considered relevant to most doctors. The reasoning approach of an evidence-based differential diagnosis which is taught to medical students is a powerful heuristic, but it is designed to work within the constraints of acute illness and (potentially) urgent intervention. So of course if fails when test results are considered without appropriate measures to improve the signal to noise ratio of the first branch of the decision tree. With any kind of broad-spectrum, speculative testing, any result would need to be considered over time and in the context of many other factors. It is not a drop-in replacement for any step of the traditional differential.
- cortesoft 10y ago
  "But with respect to tests, so long as a test has a known false positive and false negative rate, its result can be accurately factored into a probabilistic model of a patient's overall health." In order to do that, you would also need to know the correlations BETWEEN tests in terms of false positive and negative. And there are a lot of combinations.

Floegipoky 10y ago

It seems like one of the biggest issues here is that a single test for a given thing isn't enough data to be able to reliably tell whether or not the results are significant. So people are arguing that we should collect fewer data points? I totally disagree with this viewpoint. The medical community's current approach to testing (positive result, treat ALL THE THINGS!) is an artifact of the difficulty and cost of performing the tests; the inability of many providers to apply basic concepts of probability to test results should not be used as an argument against advancing the state of the art, particularly as the industry begins baking data-driven clinical decision support into automated health systems. If you have 40 tests spanning 20 years saying that you aren't at risk for Total Scrotal Implosion, and then suddenly, without any symptoms, you get a result saying your testicles will fall off tomorrow, you have context with which to interpret this result. Without the historic data there is much greater risk of you and your healthcare provider agreeing to an unnecessary knee-jerk scrotalectomy. Less data is never the answer. Just my 2 cents.

specialist 10y ago
I definitely wish I had a comprehensive log of tests over my lifetime. I'm now more interested in the changes (trends) than the absolute values.
chuckcode 10y ago
Completely agree. False positives are a fact of statistics, what we need is more data to establish baselines for people and populations and understand when is the right time to worry. I'm genuinely surprised that doctors aren't leading a charge to get more data about their patients and arguing instead for less testing and data. Do they really feel that their diagnostics are so good that they only need a few data points every couple years? My watch and phone know more about my health than my doctor.
- grey413 10y ago
  It's been addressed elsewhere in the thread, but the problem is not statistical false positives, but rather technically "true" positives (for what the test measures) that do not correlate to an actual disease. More data points do not help.

amelius 10y ago

> which means that only 27% of positive test results are right The negative test results are still right 99.8% of the time.

pessimizer 10y ago
But throwing the blood sample in the trash and just saying "You don't have it" is right 98% of the time. Would you support that test? Because I'm willing to charge you for it.

chuckcode 10y ago

Pretty disappointed with 538 on this article. The basic argument is that we shouldn't do more medical testing as doctors aren't sure how to interpret the results, public isn't sophisticated enough to understand and too lazy to do anything even if they did. Personally I feel that if we had more data over a larger group of people we would be able to learn what leads to disease better. Further I'm a little shocked that the medical industry can get away with a stated policy that patients should wait until their symptoms are acute and then get a minimum number of tests so their doctors don't get confused. I'd like to see us have more data about our health even if we're not sure what to do about it right away. Ignorance is easier to implement but isn't always bliss.

nemothekid 10y ago
>Personally I feel that if we had more data over a larger group of people we would be able to learn what leads to disease better. The article is pretty much arguing that there isn't currently a method that exists that will accurately give us more data. How useful is "more data" when 73% of it is garbage?
TeMPOraL 10y ago
> Further I'm a little shocked that the medical industry can get away with a stated policy that patients should wait until their symptoms are acute and then get a minimum number of tests so their doctors don't get confused. It's because this is a reasonable strategy, that takes into the account the actual quality of the tests, the base rate, and the fact that people are idiots^W^Woverreact dramatically when it comes to health. This is a combination of insight that most of the serious diseases are rare, so most patients will be fine if they wait a little bit more, coupled with the insight that they most definitely won't be fine if they freak out, and most of them will.

deleted 10y ago

[deleted]

lordnacho 10y ago

Something is not clear to me. How do you know that a false positive is, in fact, a false positive? I presume there are some other pieces of information that provide the reference value. So when someone gets a positive test, why not put them through the next test to see if they keep coming up positive? What's the argument for not testing in the first place? It will panic people? If that's the case, why not make it random whether you're called to an extra test?

DanBC 10y ago
> Something is not clear to me. How do you know that a false positive is, in fact, a false positive? Bob has a full body MRI. THat returns some shadowy spots on his lungs. He's asked if he used to smoke (he did), and if he had any childhood illnesses (german measles, measles, chicken pox, etc) (he did). Are those spots early cancer? Or are they just scarring from the childhood illness? One way is to cut Bob open and have a look. Or jab him with a massive biopsy needle. Except, now you know that this one spot isn't cancer, it was a scar. How about all the rest? That one biopsy increased Bob's risk of harm. > What's the argument for not testing in the first place? Testing often doesn't give any useful information. It often gives wrong information - people who have a disease are told they don't have it, and people who don't have it are told they do have it. Many of these people then go on to have treatment. All treatment carries some risk of harm. You need to know if the benefits of testing (especially of testing a large, mostly healthy population) outweigh the risks of providing risky treatment to those people, some of who will not have the disease. You also have to see what happens if you just don't do anything. Prostate cancer is a good example here. Some people will die of it - they have an aggressive cancer that will kill them rapidly. But many people will die with it - they have a slow growing tumour, and they'll die in old age from something else. Treatment for prostate cancer is pretty harsh.
Jtsummers 10y ago
> What's the argument for not testing in the first place? The wider the pool of people being tested, the greater the chance of false positives, which is why screening guidelines generally limit the population to be screened. The more independent tests you do at once, each with its own chance of error, the larger the chance that at least one of those tests produces an incorrect result, said Rebecca Goldin, director of STATS.org and a professor of mathematical sciences at George Mason University. It's not just panic, but that if the false positive rate is too high then untargeted testing becomes overwhelming and counterproductive. There's a slim, very slim, chance that as a man I could develop breast cancer. But there's little value in testing me as it's not present in my family history (male or female). So let's say (in this example) that the false positive rate is only 1% in men and the true incidence rate is 0.01%, and we test 100 million men: 10,000 men have breast cancer, great we've detected it 999,900 men don't, but are subjected to more testing That more testing is likely costly, time consuming, and potentially invasive. This acts as a net drain on medical resources because we've just performed nearly 1 million unnecessary mammograms. They take technician and physician time. They take machine time. And so on. So false positive rates may be low, but when applied to a massive population the total number of false positives can overwhelm the system.

bane 10y ago

Yeah sure, but you know...what about disruption!

tokenadult 10y ago

A lot of the comments here reveal not having read the fine article (which is not very long). If you look at the graphic labeled "How Accurate Tests Can Be Mostly Wrong," about halfway down the displayed Web article, you will see a very carefully worked out (and realistic) example about how even a very accurate medical test can result in mostly false positive indications of a disease--all that is necessary for that, mathematically, is that there is a low base rate of the disease. Examples like this have been commonplace in books about statistical reasoning for making medical decisions for more than a decade, and I have shared links to Hacker News before that make this same point. This is something everyone needs to know (but the investors in Theranos didn't know) to make sound decisions about how much testing to do and what to do with test results. Other authors who write about this issue are cited in the article kindly submitted for our discussion. I urge everyone here to read a lot of the writings of Dr. John P.A. Ioannidis,[1] who is quoted in the article. [1] https://med.stanford.edu/profiles/john-ioannidis?tab=publications https://med.stanford.edu/profiles/john-ioannidis?tab=publica...

nommm-nommm 10y ago

See also Science Based Medicine - a skeptical look at screening tests. https://www.sciencebasedmedicine.org/a-skeptical-look-at-screening-tests/ https://www.sciencebasedmedicine.org/a-skeptical-look-at-scr...

erikb 10y ago

I have very high chance of diabetes and other blood sugar related health problems, like heart diseases. I certainly think that cheap, repetitive blood tests would help me improve my health in the same way having my phone count my steps helps me to have a more active life. Please make it work. Maybe that start-up won't make, then please make another one. Thanks.

jerryhuang100 10y ago

the article and most comments here are more about EH's VISION of empowering regular people for cheap and on-demand blood tests. but the major problems the regulatory bodies, medical practioners and diagnostics experts have are mostly about theranos' underlining TECHNOLOGY, its basic SCIENCES and daily lab PRACTICES. to this date none of these three has been established at theranos (non-peer-reviewed, non-core patents, criticized by cms & fda w/ banning threats). in short, it just does not work (yet?) it's like someone always talk about building beautiful resorts or gigatic mining operations on Mars, but fails to develop rocket propulsion systems or space travelling vehicles. if there would be other someone to bring us to Mars, it must be elon musk.

jrapdx3 10y ago

After decades of practicing medicine and seeing results of countless lab tests, I tend to agree with many of the comments here. The article isn't wrong at its core, but it is sensationalizing some very important issues. The idea that lab studies yield false positives (and negatives too) is hardly novel. Of course test results can be misleading or easily misconstrued. We know a single test, or even a set of tests is rarely definitive. We know interpreting tests is an exercise in probabilistic thinking and careful practitioners rely on test results only to the extent warranted. I often get a question like "so what does this test mean?" A single anomalous reading, probably not much. I answer "it's only a test", confirming a diagnosis is a laborious process to make sure the facts align as best as can be determined. That is, the gamut of history, direct observation, and a variety of lab/imaging measurements looking at a clinical situation from several angles need to converge. In many practice domains lab/measurement technologies provide tremendous benefit. Think about the contributions of imaging (CT, MRI), endoscopy (colonoscopy, etc.), and yes, advances in medical laboratory science also save untold lives every day. Everyone here on HN knows all technologies can and will be misused but that doesn't mean they are not valuable and worthy. I take my own advice to never forget: "it's only a test", and any test is no more useful than the limits of its credibility.