6 ms·

Have heard your argument on the false positives and unnecessary interventions many times. It is not a good argument. In fact, it makes no sense. If you get a p

Have heard your argument on the false positives and unnecessary interventions many times. It is not a good argument. In fact, it makes no sense. If you get a positive with an uncertainty in its accuracy, at the very least, the test is repeated. But even more, you can use the information from the investigation of the reason for the false positive to improve the tests in the first place. If we weren't humans and the uncertainty of the test is known then at the very very very least you could throw a dice to decide whether you discard or not the test result. If more information leads to worse decisions it just means that the noise level introduced by the test is just too high. A way to reduce the noise is two amplify the signal, and a way to amplify the signal is to look for more information (other tests, other indirect measurements: i.e., look for B if A was positive, etc.).

ggrrhh_ta 5y ago
BTW... years ago I was rather supportive (albeit not having voiced it) of the argument that false positives lead to unnecessary interventions and thus screening should be itself gated.
- jacquesm 5y ago
  Your understanding as evinced by the comment above leaves me to wonder if you actually get that this is not about individual outcomes but about the overall statistics. Even if more accurate tests would turn up more true positives that still would not necessarily result in increased patient outcomes. That is why absent symptoms testing makes sense for only a very low number of cancers where early detection does improve patient outcomes significantly, typically this is vastly improved if there is knowledge about the genetical make-up of the individuals.
  - nybble41 5y ago
    > absent symptoms A positive blood test is a symptom. One which you'll miss if you don't do the blood test regularly. And looking for symptoms (other than a blood test) is a form of testing... one with much worse accuracy (both positive and negative) than the blood test, especially in the early stages.
    - jacquesm 5y ago
      Just so we are using the same definitions for the words we write, here is the definition of 'symptom' in a medical context: https://www.cancer.gov/publications/dictionaries/cancer-terms/def/symptom https://www.cancer.gov/publications/dictionaries/cancer-term... "A physical or mental problem that a person experiences that may indicate a disease or condition. Symptoms cannot be seen and do not show up on medical tests. Some examples of symptoms are headache, fatigue, nausea, and pain."
      - nybble41 5y ago
        That still sounds like a subset of medical testing to me, where you're using the patient as your test equipment and ignoring anything the patient cannot sense directly (or fails to report). Perhaps you don't call the results of medical tests "symptoms", but to me this is an insignificant distinction. Either way we're talking about an observable result of some underlying condition; only the means of observation varies. Jargon aside, this approach still means waiting until after the condition has already affected the patient's quality of life, and perhaps beyond the point where it can be treated effectively, when it could have been treated and perhaps even cured before any symptoms manifested.
    - rocho 5y ago
      That's not what symptoms are.
jacquesm 5y ago
Your belief has no representation in medical science, which is mostly evidence based. A lot of data has been collected on this, studies (many) have been conducted and the general consensus is that more testing absent symptoms does not lead to improved patient outcomes. That you want to have some kind of theoretical argument in the face of this evidence might be interesting to you but it isn't to me.
- dmitryminkovsky 5y ago
  Not just that, but neither GP nor anyone else in this thread seems to be mentioning the mental health implications of constantly screening for life threatening diseases. For me, and many others I am sure, this would be bad. My quality of life would suffer tremendously, to the point of likely substantial loss of mental function. And I am definitely not one of these “we all die someday” types. Far from it. It’s just that if you’re prone to anxiety, especially the hypochondriasis variety, the picture is much more complex than thinking of yourself as a server hooked up to monitoring.
  - jacquesm 5y ago
    Yes, that's a very important point. Even regular checks for cervical cancer or breast cancer can be a huge stress factor, especially in the period just prior to the test and in the waiting period until the results are in, and even more so if the test yields a false positive.
    - mrtnmcc 5y ago
      Is the problem not so much the testing, but that most current treatments for cancers are so crude? If you have a relatively asymptomatic cancer, the treatments (chemo, surgery, proton beams) and psychological stress of discovery could be worse (statistically) than letting the body naturally take care of it. This probably depends very much on the cancer ( e.g., some Thyroid cancers might be better left alone). If our best treatment for fixing a harddrive was to hit it with a hammer, then maybe we'd also conclude monitoring for minor bit errors in data centers is unwise too.
fabian2k 5y ago
This is a very well known problem for many kinds of screenings, and the solution is not as simple as you claim. You can't just repeat the test, that is generally not where the problem lies. You'll get a second positive result and still don't know if it's a false positive or not. And in many cases there aren't other non-invasive test you can perform. If you can't actually determine reliably if some anomaly will cause trouble before removing it, whole population screening will cause unnecessary operations.
- deleted 5y ago
  [deleted]
dxyms 5y ago
>If you get a positive with an uncertainty in its accuracy, at the very least, the test is repeated. But even more, you can use the information from the investigation of the reason for the false positive to improve the tests in the first place. This assumes that the false positive is caused randomly. That's not the case. False positive tests are usually followed by false positive tests. Then it will take years to find out if it was a false positive or not.
- ggrrhh_ta 5y ago
  That is very interesting. I assumed that false positives is generally a testing error (testing with another method or from another company would not lead to the same result). If the false positive is a result of a non-dangerous anomaly of the person being tested, then, I see how testing without symptoms can be worse.
  - jghn 5y ago
    Herein lies the real issue. Biology is a very, very messy science. So yes it could just be a testing error. But it might not be. It might be that something in your body behaves in a way that's unexpected. It might be some other non-dangerous anomaly as you cite. We understand far more than we did say 20 years ago. But the problems are non-trivial on a scale most people don't appreciate.

ggrrhh_ta 5y ago

BTW... years ago I was rather supportive (albeit not having voiced it) of the argument that false positives lead to unnecessary interventions and thus screening should be itself gated.

jacquesm 5y ago
Your understanding as evinced by the comment above leaves me to wonder if you actually get that this is not about individual outcomes but about the overall statistics. Even if more accurate tests would turn up more true positives that still would not necessarily result in increased patient outcomes. That is why absent symptoms testing makes sense for only a very low number of cancers where early detection does improve patient outcomes significantly, typically this is vastly improved if there is knowledge about the genetical make-up of the individuals.
- nybble41 5y ago
  > absent symptoms A positive blood test is a symptom. One which you'll miss if you don't do the blood test regularly. And looking for symptoms (other than a blood test) is a form of testing... one with much worse accuracy (both positive and negative) than the blood test, especially in the early stages.
  - jacquesm 5y ago
    Just so we are using the same definitions for the words we write, here is the definition of 'symptom' in a medical context: https://www.cancer.gov/publications/dictionaries/cancer-terms/def/symptom https://www.cancer.gov/publications/dictionaries/cancer-term... "A physical or mental problem that a person experiences that may indicate a disease or condition. Symptoms cannot be seen and do not show up on medical tests. Some examples of symptoms are headache, fatigue, nausea, and pain."
    - nybble41 5y ago
      That still sounds like a subset of medical testing to me, where you're using the patient as your test equipment and ignoring anything the patient cannot sense directly (or fails to report). Perhaps you don't call the results of medical tests "symptoms", but to me this is an insignificant distinction. Either way we're talking about an observable result of some underlying condition; only the means of observation varies. Jargon aside, this approach still means waiting until after the condition has already affected the patient's quality of life, and perhaps beyond the point where it can be treated effectively, when it could have been treated and perhaps even cured before any symptoms manifested.
  - rocho 5y ago
    That's not what symptoms are.

jacquesm 5y ago

Your belief has no representation in medical science, which is mostly evidence based. A lot of data has been collected on this, studies (many) have been conducted and the general consensus is that more testing absent symptoms does not lead to improved patient outcomes. That you want to have some kind of theoretical argument in the face of this evidence might be interesting to you but it isn't to me.

dmitryminkovsky 5y ago
Not just that, but neither GP nor anyone else in this thread seems to be mentioning the mental health implications of constantly screening for life threatening diseases. For me, and many others I am sure, this would be bad. My quality of life would suffer tremendously, to the point of likely substantial loss of mental function. And I am definitely not one of these “we all die someday” types. Far from it. It’s just that if you’re prone to anxiety, especially the hypochondriasis variety, the picture is much more complex than thinking of yourself as a server hooked up to monitoring.
- jacquesm 5y ago
  Yes, that's a very important point. Even regular checks for cervical cancer or breast cancer can be a huge stress factor, especially in the period just prior to the test and in the waiting period until the results are in, and even more so if the test yields a false positive.
  - mrtnmcc 5y ago
    Is the problem not so much the testing, but that most current treatments for cancers are so crude? If you have a relatively asymptomatic cancer, the treatments (chemo, surgery, proton beams) and psychological stress of discovery could be worse (statistically) than letting the body naturally take care of it. This probably depends very much on the cancer ( e.g., some Thyroid cancers might be better left alone). If our best treatment for fixing a harddrive was to hit it with a hammer, then maybe we'd also conclude monitoring for minor bit errors in data centers is unwise too.

fabian2k 5y ago

This is a very well known problem for many kinds of screenings, and the solution is not as simple as you claim. You can't just repeat the test, that is generally not where the problem lies. You'll get a second positive result and still don't know if it's a false positive or not. And in many cases there aren't other non-invasive test you can perform. If you can't actually determine reliably if some anomaly will cause trouble before removing it, whole population screening will cause unnecessary operations.

deleted 5y ago
[deleted]

dxyms 5y ago

>If you get a positive with an uncertainty in its accuracy, at the very least, the test is repeated. But even more, you can use the information from the investigation of the reason for the false positive to improve the tests in the first place. This assumes that the false positive is caused randomly. That's not the case. False positive tests are usually followed by false positive tests. Then it will take years to find out if it was a false positive or not.

ggrrhh_ta 5y ago
That is very interesting. I assumed that false positives is generally a testing error (testing with another method or from another company would not lead to the same result). If the false positive is a result of a non-dangerous anomaly of the person being tested, then, I see how testing without symptoms can be worse.
- jghn 5y ago
  Herein lies the real issue. Biology is a very, very messy science. So yes it could just be a testing error. But it might not be. It might be that something in your body behaves in a way that's unexpected. It might be some other non-dangerous anomaly as you cite. We understand far more than we did say 20 years ago. But the problems are non-trivial on a scale most people don't appreciate.