5 ms·

Disclosure: I'm an M.D. (Which may impact my objectivity about why skipping out on seeing a doctor is a bad idea.) Without an exhaustive review of the implicat

Disclosure: I'm an M.D. (Which may impact my objectivity about why skipping out on seeing a doctor is a bad idea.) Without an exhaustive review of the implications of Bayes' Theorem, suffice it to say that this isn't necessarily a good idea. The short version is: if you are unlikely to have a medical condition, a positive result may well be a false positive. Much like a full-body MRI with no medical indication, there is a risk of a false positive leading to more expensive, unnecessary, and possibly dangerous procedures to chase down a condition that doesn't exist. Going "directly to the lab" is, for many people, predicated on an overly simplistic and idealistic understanding of how lab tests work. The context of the result (health history, family history, physical exam, etc.) is important for accurate interpretation. Finally, some tests border on the fraudulent. I'm a psychiatrist, and increasingly tests to make a psychiatric diagnosis based on a genetic screening are being marketed directly to patients. These tests are not generally accepted in the medical community as being accurate. In fact, some them are very likely to be totally misleading. Caveat emptor.

jluxenberg 17y ago
Sure, but for something simple like an STD screen or cholesterol surely these results are unambiguous? The article says these tests can be "at a cost that is as much as 80 percent less than going through a doctor", what can explain that kind of discrepancy besides rampant corruption in the "official" medical lab work market?
- phren0logy 17y ago
  Cholesterol: Probably. STD: Depends on which one. Cost: I don't know why the difference is so large; that seems like a serious problem. For what it's worth, I don't make a single extra penny on lab tests. As far as I know, most doctors don't (except maybe the pathologist who runs the lab). We just order what's indicated.
  - carbocation 17y ago
    I must say that I take a slightly different position on cholesterol. People seem to have a very difficult time interpreting the different values, particularly as most people cannot distinguish HDL from LDL from TGs. Plus, ATP-III recommends different limits on LDL-C for patients with different risk factors. Would I say that the average person should be able to get a cholesterol test if they want it? From a rights/freedom standpoint, absolutely. Would I worry that they would misinterpret it without guidance? From a medical standpoint, absolutely.
    - phren0logy 17y ago
      Good point; maybe reading them all the time makes me underestimate what's involved.
- Zak 17y ago
  The cost of two office visits (an initial consultation in which the test is ordered and a second to receive the results) might be enough to account for the difference. The company mentioned in the article appears to charge $49 for a variety of tests.
- pchivers 17y ago
  The article says these tests can be "at a cost that is as much as 80 percent less than going through a doctor", what can explain that kind of discrepancy besides rampant corruption in the "official" medical lab work market? The difference is that one is paid for by a health insurance company, and the other is paid for out of pocket by the consumer. The second group is much more price sensitive.
Zak 17y ago
To provide a counterpoint, I've seen a number of situations where doctors simply refused to investigate properly, instead assuming that symptoms were the result of the most common disorder capable of causing them. I'm firmly on the side of patients having access to whatever sort of tests they want without the aid of a doctor. Should they draw the wrong conclusions from those tests, well, you already said it: caveat emptor. I am not, however opposed to some restrictions on what labs can claim about their tests.
- phren0logy 17y ago
  There's a saying we learned in medical school: "When you hear hoof-beats, think horses not zebras." Ordering tests for every possible condition that could cause presenting symptoms is usually not the right idea. It's a difficult problem, because sometimes it really is a zebra. That's part of the art of medicine. But not every child with a bloody nose needs a bone-marrow biopsy. That means that a child with serious blood coagulation problem may not get one with the first nose bleed. Is that a bad call? If you are that kid, you might think so. There's no easy answer, only thoughtful trade-offs.
  - Zak 17y ago
    I'm not saying you're wrong. What I am saying is that putting more power in the hands of patients is a good thing. I'm also saying that in my experience, there seems to be a tendency for doctors to ignore the patient saying "but it has stripes". For a case in point, see http://news.ycombinator.com/item?id=668195 http://news.ycombinator.com/item?id=668195
    - carbocation 17y ago
      I disagree that letting people order lab tests for themselves is, on balance, a good thing for the population's health. I agree that it is something that should nevertheless be allowed, in many cases, under the aegis of individual freedom.
    - carbocation 17y ago
      As an aside, in the heavy bleeding described in the post that you linked to sounds like classical endometriosis, particularly since it was resolved by GnRH. If so, it is rather surprising that your doctors did not figure this out; most medical students could.
deleted 17y ago
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- deleted 17y ago
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rms 17y ago
Hey there. I have a personal interest in genetic testing for mental health, the goal being to help psychiatrists make the decision about which anti-depressant to try first. The conclusion was the 5-HTT gene was the only one mutation where the research was verified enough to have a chance of being used right now, and that gene doesn't help make any treatment decisions. I think it'll be at least 10 years before mental health genetic testing becomes mandated by insurance, though maybe faster if improve outcomes can be readily demonstrated. I think one of the main consequences is that NRIs are going to be more widely prescribed than they are right now, because of mutated BDNF genes. http://jama.ama-assn.org/cgi/content/full/296/13/1609?maxtoshow=&HITS=10&hits=10&RESULTFORMAT=&fulltext=Hyeran+Kim&searchid=1&FIRSTINDEX=0&resourcetype=HWCIT http://jama.ama-assn.org/cgi/content/full/296/13/1609?maxtos... I of course agree with you about the presence of doctors in these processes. Genetic testing is only really meaningful when interpreted by the doctors in the context of all of the other important information.
- phren0logy 17y ago
  Awesome. I don't mean to imply that I'm not excited about the promise of genetic testing for mental health. I'm just frustrated about the direct marketing of tests with dubious value to make a fast buck off of vulnerable patients.
  - rms 17y ago
    Can you send me an email or post your email address in the profile? I'd like to know what demonstrated validity you would need before using a genetic test to help make medication decisions. Right now I could bundle and sell a panel of genetic tests (Costing somewhere between $199 and $499 based on market research) to help psychiatrists make a decision about the first medication to try, but most of the research is one-off studies in limited populations. The 5-HTT one is the only one that's been well replicated; people with the right 5-HTT polymorphism respond to SSRIs.
    - phren0logy 17y ago
      I'd need Positive and Negative Likelihood Ratios published in a peer-reviewed publication gathered from a population similar to the one I was treating. Preferably multi-site, and with replication of results by another independent research group.
yummyfajitas 17y ago
In all fairness, plenty of doctors also don't understand Bayes theorem and conditional probability. I've had to explain to two doctors on separate occasions that P(A | B) ~ 0 does not imply that P(B | A) ~ 0.

jluxenberg 17y ago

Sure, but for something simple like an STD screen or cholesterol surely these results are unambiguous? The article says these tests can be "at a cost that is as much as 80 percent less than going through a doctor", what can explain that kind of discrepancy besides rampant corruption in the "official" medical lab work market?

phren0logy 17y ago
Cholesterol: Probably. STD: Depends on which one. Cost: I don't know why the difference is so large; that seems like a serious problem. For what it's worth, I don't make a single extra penny on lab tests. As far as I know, most doctors don't (except maybe the pathologist who runs the lab). We just order what's indicated.
- carbocation 17y ago
  I must say that I take a slightly different position on cholesterol. People seem to have a very difficult time interpreting the different values, particularly as most people cannot distinguish HDL from LDL from TGs. Plus, ATP-III recommends different limits on LDL-C for patients with different risk factors. Would I say that the average person should be able to get a cholesterol test if they want it? From a rights/freedom standpoint, absolutely. Would I worry that they would misinterpret it without guidance? From a medical standpoint, absolutely.
  - phren0logy 17y ago
    Good point; maybe reading them all the time makes me underestimate what's involved.
Zak 17y ago
The cost of two office visits (an initial consultation in which the test is ordered and a second to receive the results) might be enough to account for the difference. The company mentioned in the article appears to charge $49 for a variety of tests.
pchivers 17y ago
The article says these tests can be "at a cost that is as much as 80 percent less than going through a doctor", what can explain that kind of discrepancy besides rampant corruption in the "official" medical lab work market? The difference is that one is paid for by a health insurance company, and the other is paid for out of pocket by the consumer. The second group is much more price sensitive.

Zak 17y ago

To provide a counterpoint, I've seen a number of situations where doctors simply refused to investigate properly, instead assuming that symptoms were the result of the most common disorder capable of causing them. I'm firmly on the side of patients having access to whatever sort of tests they want without the aid of a doctor. Should they draw the wrong conclusions from those tests, well, you already said it: caveat emptor. I am not, however opposed to some restrictions on what labs can claim about their tests.

phren0logy 17y ago
There's a saying we learned in medical school: "When you hear hoof-beats, think horses not zebras." Ordering tests for every possible condition that could cause presenting symptoms is usually not the right idea. It's a difficult problem, because sometimes it really is a zebra. That's part of the art of medicine. But not every child with a bloody nose needs a bone-marrow biopsy. That means that a child with serious blood coagulation problem may not get one with the first nose bleed. Is that a bad call? If you are that kid, you might think so. There's no easy answer, only thoughtful trade-offs.
- Zak 17y ago
  I'm not saying you're wrong. What I am saying is that putting more power in the hands of patients is a good thing. I'm also saying that in my experience, there seems to be a tendency for doctors to ignore the patient saying "but it has stripes". For a case in point, see http://news.ycombinator.com/item?id=668195 http://news.ycombinator.com/item?id=668195
  - carbocation 17y ago
    I disagree that letting people order lab tests for themselves is, on balance, a good thing for the population's health. I agree that it is something that should nevertheless be allowed, in many cases, under the aegis of individual freedom.
  - carbocation 17y ago
    As an aside, in the heavy bleeding described in the post that you linked to sounds like classical endometriosis, particularly since it was resolved by GnRH. If so, it is rather surprising that your doctors did not figure this out; most medical students could.

deleted 17y ago

[deleted]

deleted 17y ago
[deleted]

rms 17y ago

Hey there. I have a personal interest in genetic testing for mental health, the goal being to help psychiatrists make the decision about which anti-depressant to try first. The conclusion was the 5-HTT gene was the only one mutation where the research was verified enough to have a chance of being used right now, and that gene doesn't help make any treatment decisions. I think it'll be at least 10 years before mental health genetic testing becomes mandated by insurance, though maybe faster if improve outcomes can be readily demonstrated. I think one of the main consequences is that NRIs are going to be more widely prescribed than they are right now, because of mutated BDNF genes. http://jama.ama-assn.org/cgi/content/full/296/13/1609?maxtoshow=&HITS=10&hits=10&RESULTFORMAT=&fulltext=Hyeran+Kim&searchid=1&FIRSTINDEX=0&resourcetype=HWCIT http://jama.ama-assn.org/cgi/content/full/296/13/1609?maxtos... I of course agree with you about the presence of doctors in these processes. Genetic testing is only really meaningful when interpreted by the doctors in the context of all of the other important information.

phren0logy 17y ago
Awesome. I don't mean to imply that I'm not excited about the promise of genetic testing for mental health. I'm just frustrated about the direct marketing of tests with dubious value to make a fast buck off of vulnerable patients.
- rms 17y ago
  Can you send me an email or post your email address in the profile? I'd like to know what demonstrated validity you would need before using a genetic test to help make medication decisions. Right now I could bundle and sell a panel of genetic tests (Costing somewhere between $199 and $499 based on market research) to help psychiatrists make a decision about the first medication to try, but most of the research is one-off studies in limited populations. The 5-HTT one is the only one that's been well replicated; people with the right 5-HTT polymorphism respond to SSRIs.
  - phren0logy 17y ago
    I'd need Positive and Negative Likelihood Ratios published in a peer-reviewed publication gathered from a population similar to the one I was treating. Preferably multi-site, and with replication of results by another independent research group.

yummyfajitas 17y ago

In all fairness, plenty of doctors also don't understand Bayes theorem and conditional probability. I've had to explain to two doctors on separate occasions that P(A | B) ~ 0 does not imply that P(B | A) ~ 0.