[HN Gopher] When they warn of rare disorders, these prenatal tes...
___________________________________________________________________
When they warn of rare disorders, these prenatal tests are usually
wrong
Author : phsource
Score : 85 points
Date : 2022-01-02 17:49 UTC (5 hours ago)
(HTM) web link (www.nytimes.com)
(TXT) w3m dump (www.nytimes.com)
| gwern wrote:
| This article is a confused mess. It's something of a Gish gallop
| in conflating all the different issues they could come up with,
| while leaving out all the necessary vocabulary (C-f "Bayes"
| "posterior" "decision theory" [Phrase not found]) making it
| almost impossible to consider each issue in adequate detail.
|
| It mixes up poor communication (reporting false-positive/negative
| rates as if posterior probabilities, & exaggerated confidence
| thereof), arbitrary-seeming decision thresholds (but their
| hyperventilating over '85% wrong' notwithstanding, many are
| probably too conservative, if anything, given how devastating
| many of these problems are, there should be _more_ false
| positives to trigger additional testing, not less), costs of
| testing (sure why not but little is presented), tests which they
| claim just bad and uninformative (developed based on far too
| little _n_, certainly possible), implicit calls for the FDA to Do
| Something and ban the tests (not an iota of cost-benefit
| considered nor any self-reflection about whether we want the FDA
| involved in anything at all these days)... Sometimes in the same
| paragraph.
|
| Plenty of valid stuff could be written about each issue, but
| they'd have to be at least 4 different articles of equivalent
| length to shed more light than heat.
| creata wrote:
| > implicit calls for the FDA to Do Something and ban the tests
|
| Not that you're necessarily wrong, but how did you get that
| from the article? It didn't seem to me like they wanted a ban.
| mcguire wrote:
| So you are saying the testing companies in the article _aren
| 't_ fraudulently claiming much more effective tests than they
| are providing?
| jrockway wrote:
| Specificity and sensitivity are two dimensions that you can
| measure tests in. You can claim your test is 99% accurate if
| you mean that "if the test says you don't have the disease,
| there is a 99% chance that you don't have the disease". That
| same test can still be 85% wrong if it says you DO have the
| disease, though.
|
| I doubt that hyping one side of this equation is fraud.
| Pushing the error in this direction seems like a good idea,
| anyway. If you have some weird illness, and the test comes
| back as a false positive, at least you'll continue to explore
| that possibility for a while. If it comes back as a false
| negative, then you'll spend a ton of time exploring
| alternatives which will be true negatives. Probably
| infuriating.
|
| https://en.wikipedia.org/wiki/Sensitivity_and_specificity
| bscphil wrote:
| They even missed "base rate", which is the way I usually see
| this explained to ordinary people without stats backgrounds.
| Really disappointing.
| SpicyLemonZest wrote:
| They don't use that specific term, but the Down syndrome
| infographic does a pretty solid job at explaining the base
| rate issue.
| hn_throwaway_99 wrote:
| > implicit calls for the FDA to Do Something and ban the tests
| (not an iota of cost-benefit considered nor any self-reflection
| about whether we want the FDA involved in anything at all these
| days)...
|
| This is true in so many areas of journalism but lately seems
| especially egregious in the NYT. And I don't really blame them,
| as the incentives for any individual reporter are just too
| great - having the government make a major policy change based
| on your article is basically the brass ring for an
| investigative reporter.
|
| I basically can only use these types of articles as a jumping
| off point for my own research, as I usually find the moralizing
| conclusion the article comes to as unsupported.
| nohuck13 wrote:
| "the incentives for any individual reporter are just too
| great - having the government make a major policy change
| based on your article is basically the brass ring for an
| investigative reporter"
|
| Yep, this is the framing I came here looking for.
|
| Investigative journalists live in the same asymmetrically-
| incentivized world as social science researchers. If the
| reporter had looked into the phenomenon and concluded "yeah,
| boring technical logic pretty much works as expected here"
| then there's no story.
| csee wrote:
| > "The chance of breast cancer is so low, so why are you doing
| it? I think it's purely a marketing thing."
|
| This mindset is ingrained in every doctor I speak to, but I think
| it's just so wrong.
|
| Take DiGeorge syndrome. You have a 1/4000 chance of having it,
| and the test carries an 81% chance of a false positive. The above
| doctor calls this "marketing"? Foolishness. That's an incredibly
| useful test. The downside is small, and the upside is
| asymmetrically large.
|
| We need far, far better screening for all sorts of things. Adult
| cancer and heart screens once a year, prenatal screening, and on.
| We do a good job with breast and prostate screens, but for rarer
| conditions our current approach of waiting for the disease to be
| symptomatic makes no sense. Part of that will be driving the cost
| down. There is so much market need for a legitimate version of
| Theranos and I'm glad there are some companies working on these
| things.
| lostlogin wrote:
| > We do a good job with breast and prostate screens
|
| Do we? Unless I'm missing something, breast cancer is a huge
| killer and PSA tests are deeply imperfect. I am very much not
| expert in these areas.
| [deleted]
| dougmwne wrote:
| Wow, what an embarrassing mess. Front page feature of bad
| statistics and bad medicine.
| sklargh wrote:
| I recall a period in the early 2000s when unindicated whole-body
| CAT-scans were being advertised on television.
|
| That got knocked down pretty quickly but wow a lot of folks
| picked up a big chunk of their lifetime radiation allowance
| because of that.
|
| These tests seem to operate under a similar model, disregard the
| risks of unnecessary testing in return for information of limited
| utility that may cause material harm.
| bdzr wrote:
| I think you're conflating "these tests cause harm" e.g.
| radiation and "the information gleaned from these tests could
| cause the patient to make poor decisions". Having a regulatory
| body make this value judgement for people has quite a bit of
| disadvantages. See "DON'T TRY THIS AT HOME: THE FDA'S
| RESTRICTIVE REGULATION OF HOME-TESTING DEVICES" https://scholar
| ship.law.duke.edu/cgi/viewcontent.cgi?article....
| Enginerrrd wrote:
| This isn't really a fair criticism. I could be wrong, but I
| believe your comment reflects a bit of naivete about the
| current state of evidence-based medicine.
|
| To evaluate the value of performing a diagnostic test as an
| intervention, you DO have to look at final actual patient
| outcomes at an appropriate end target which includes sending
| people unnecessarily down different treatment paths,
| including additional testing with additional risks. And most
| importantly is that, in fact, mere knowledge of diagnostic
| results has been PROVEN to cause harm in many scenarios.
|
| Now... if a patient WANTS that test, I think it should be
| available. But whether or not it should be performed
| routinely without prompting is an appropriate question for
| regulatory bodies.
| sjckciodjcr wrote:
| This article seems a bit deceptive. We are going through NIPT
| soon and our doctor went over false positive and false negative
| rates for the common screens. Our doctor has pointed out some of
| the screens (esp for rare conditions) are not that accurate. The
| only procedure with high accuracy, amniocentesis, has a slight
| risk of miscarriage (our provider quoted 0.3% ) so its still
| statistically better to take NIPT and then only consider
| amniocentesis with a positive result since there is no risk from
| NIPT.
|
| You are supposed to treat a positive on NIPT as "there's a chance
| your baby has this, need a more accurate procedure to confirm".
|
| It sounds like their ob gyn wasn't able to explain results to
| them or they didn't understand the probabilities. To be fair our
| provider didn't even suggest tests for the disorders in the
| article, probably because of the false positive rates and rarity.
| Sounds like these extra screens shouldn't be offered.
| SpicyLemonZest wrote:
| "These extra screens shouldn't be offered" seems like exactly
| the point the article is trying to make.
| [deleted]
| tmnstr85 wrote:
| My 2nd daughter was flagged during our 20 week for something
| having to do with the way her skull was forming and they wanted
| to do a series of genetic test. They charged us through the wazoo
| and everything came back negative. She arrived 3.5 weeks early
| and contracted bacterial meningitis shortly after birth. We found
| her code blue in the crib. She ended up having a bilateral
| craniotomy to relieve the empyema that had formed. CP, CVI,
| global TBI - every day is hell on earth. This was 2019, so the
| nightmare of the last few years started early for our family.
| We've had a number of medical professionals drop hints at the
| fact there might be something wrong from a rare disorder
| perspective but we're in a league of our own and that is
| hindsight - the damage and trauma are non-stop. Anyone trying to
| shickle a few dollars from the medical system to provide "pre-
| natal diagnosis" without sound science - they can come burn in
| the same hell I live in every day.
| jasonhansel wrote:
| IMHO, some of those criticizing the article for failing to
| understand statistics are missing the point.
|
| The point is that people who get a "positive" result on these
| tests are often put through terrifying levels of anxiety when
| there is no actual problem; this anxiety is often exacerbated
| because they aren't informed of the false positive rate. This
| clearly has a harmful emotional effect on people, and explaining
| the false positives in Bayesian terms, or reframing it in terms
| of sensitivity and specificity, doesn't undo that damage.
|
| That potential harm needs to be explained to patients, and it
| needs to be weighed carefully against the potential benefits of
| the test (as is done for PSA tests for prostate cancer, which
| also have a high false positive rate). Given that potential for
| harm, it's not unreasonable to ask that these tests be more
| tightly regulated.
|
| To quote the OP:
|
| > In interviews, 14 patients who got false positives said the
| experience was agonizing. They recalled frantically researching
| conditions they'd never heard of, followed by sleepless nights
| and days hiding their bulging bellies from friends. Eight said
| they never received any information about the possibility of a
| false positive, and five recalled that their doctor treated the
| test results as definitive.
|
| (Edit: clarified)
| midjji wrote:
| If you get a positive for a horrid cancer with a 90 percent
| false positives you should be afraid. Its lunacy for tests to
| be regulated beyond requiring rough false positive false
| negative rates, and if anything smacks of "I dont understand
| statistics and therefore have to protect my children from
| understanding statistics." The article is most likely written
| by some anti abortion idiot.
| don-code wrote:
| I am not a parent, but the criticism of the article appears to be
| around a misunderstanding of statistics, or at least how to apply
| them. While I agree that criticism is completely correct, it
| overlooks the human nature of the people receiving the tests. At
| an already-stressful point in someone's life, it seems almost
| like bad bedside manner for the medical community, even if in an
| automated fashion, to tell people that there might be a
| complication looming.
|
| This _does_, however, seem like a framing issue, more than a
| utility issue. If the tests are 100% accurate at detecting true
| positives, they're a great aid. But rather than framing the tests
| as a be-all, end-all source for information, why not frame them
| as "a test that suggests whether or not you should get other
| tests"? That simple wording change would save a great deal of
| added stress on someone starting or growing a family.
| isoprophlex wrote:
| I totally agree with this. Managing perceptions and
| expectations is super important here.
|
| Having been on the receiving end of a false positive, I'd still
| do the test again for a hypothetical future pregnancy. Even
| though it was hell for a couple of days.
| divbzero wrote:
| Isn't that often true with screens in general? The threshold
| often allows a good number of false positives in order to
| minimize false negatives. The goal is to know when to seek
| further diagnostics. Communicating that to patients can be a
| challenge but it doesn't mean the screens were designed
| incorrectly.
| halpert wrote:
| How did this article, written by someone who clearly lacks an
| understanding of basic statistics, make it into the Upshot? They
| try to make it seem like the test is wrong 85% of the time, but
| that's not necessarily the case. All we know from the article is
| that 85 / 100 positive results are false positives, which means
| the test could actually be quite accurate. If the test correctly
| identifies 100% of real cases, then that sounds like an excellent
| test. Just as an example, if 1/4000 people have the disease, and
| the test identifies 100% of these cases, then around 0.14% of
| test takers will get a false positive.
| mcguire wrote:
| Would a test that reported 100% positive similarly be "quite
| accurate"? It would catch _all_ true positives, right?
| ellisv wrote:
| I disagree. It is clear from the title, "When They Warn of Rare
| Disorders, These Prenatal Tests Are Usually Wrong", and the
| lead that they're focusing on false positives.
| halpert wrote:
| It's true they are focusing on false positives, but the
| authors are using the ratio of false positives to true
| positives to paint a picture that the tests are inaccurate,
| when in reality the tests are accurate. What this article is
| looking at is called the "sensitivity" of a test:
| https://en.wikipedia.org/wiki/Sensitivity_and_specificity
| adjkant wrote:
| While the author may not be well versed or focusing on the
| stats side, you're missing the human side here I think.
|
| > the tests are inaccurate, when in reality the tests are
| accurate
|
| If the test make someone consider terminating a pregnancy
| or even considering it, that's a lot of pain. So for that
| human, the test is failing its purpose potentially,
| depending on the value calculation of terminating a viable
| pregnancy vs the severity of the issue if it comes to term.
|
| For a human, accuracy as you defined it means little to
| nothing. Usefulness and helpfulness are far better metrics,
| and such a high false positive rate is clearly causing
| issues in respect to those, which is what the article is
| highlighting.
| halpert wrote:
| Or maybe you're missing the human side of having a child
| born with a serious genetic defect?
| mcguire wrote:
| Is it better to terminate 85 pregnancies which do not
| have a serious defect in order to catch 15 which do? At
| what point is it not better to terminate 100% of
| pregnancies?
| loeg wrote:
| > Is it better to terminate 85 pregnancies which do not
| have a serious defect in order to catch 15 which do?
|
| Yes, it's absolutely better to do that. Of course, the
| actual ratio is much better than that because we do
| follow-up tests after the screen.
| paulryanrogers wrote:
| > At what point is it not better to terminate 100% of
| pregnancies?
|
| Everyone should decide for themselves. Having seen the
| long term consequences I would rather err on the side of
| caution, even if it were difficult to become pregnant.
|
| Such diseases are often incurable and significantly
| degrade the quality of life of not only the person to be
| born but the whole immediate family. At least in the US
| the there isn't enough social safety net or support too
| offset the crushing costs.
| andreilys wrote:
| _Usefulness and helpfulness are far better metrics, and
| such a high false positive rate is clearly causing issues
| in respect to those_
|
| How exactly do you plan on codifying usefulness and
| helpfulness?
|
| A high false positive rate is not necessarily a bad thing
| and may instead be the catalyst for additional tests to
| confirm the first one. The tests accuracy may actually be
| 100%, which is great because it avoids a child being born
| with a fatal genetic disease. Would you prefer a high
| false negative rate that misses these diseases instead?
| mnw21cam wrote:
| No, the article isn't talking about sensitivity. We don't
| actually know what the sensitivity is from the data the
| article gives us. We are told that lots of people were
| screened and a small number had a positive result, of which
| a proportion were actually positive. You can't calculate
| sensitivity from that because you don't know how many
| actually positive cases were missed.
|
| This article is talking about precision, which is the
| proportion of positive results that are true. And it's okay
| for precision to be awful, especially when the condition is
| so rare. But it's only okay if the result is communicated
| alongside a statement saying what the precision is, which
| it seems these were not.
| halpert wrote:
| Yes you are correct.
| wizee wrote:
| The issue is that the tests portray themselves as being
| accurate (in the sense of low false positive rates), and
| portray the result as "your baby has XYZ rare syndrome"
| instead of "your baby has a 15% change of having XYZ rare
| syndrome". If the test providers stated the false positive
| rate for their results more clearly, parents would be in a
| better position to make informed decisions.
| rflrob wrote:
| The larger issue as I see it is that the medical system
| around these screenings are not well versed in the
| statistics and able to communicate that to patients.
| "Eight [patients] said they never received any
| information about the possibility of a false positive,
| and five recalled that their doctor treated the test
| results as definitive." It's hard to know what happened
| in the room when the doctor spoke with them or what was
| on those particular patients tests, and that's (one
| hopes) the worst medical news those people will receive
| for a long time so listening comprehension is
| understandably impaired, but there needs to someone
| available who can help them interpret, even days or weeks
| later, and these people were let down by the entire
| system, not just the test manufacturers.
| ramraj07 wrote:
| Did they use the word accurate? You used the word accurate
| and then you yourself are going on a tirade about how
| that's not correct?
|
| It's clear the article is talking about why sensitivity is
| important in layman's terms and while it could use better
| writing it's a real problem in diagnostics. This is why you
| don't ask men to take a pregnancy test to check for
| prostrate cancer. It is accurate but not sensitive.
| halpert wrote:
| They used the word "wrong". Whether or not they used
| wrong to mean inaccurate, or wrong to mean not sensitive
| is up to the reader.
| SpicyLemonZest wrote:
| Their infographics convince me that they understand the
| statistics. But one of the key issues here is that the
| statistics are radically counterintuitive in a way that most
| people _don 't_ understand - the patients, the testing
| companies, and even some medical staff all incorrectly believe
| that a positive test for a rare condition means you probably
| have the condition.
| halpert wrote:
| Their graphics say the tests are "84% wrong." Do you really
| feel that's an accurate description? That doesn't feel like
| an accurate description to me, and their usage of "wrong" in
| this context highlights that they don't understand the
| distinction and importance of true positives, false
| positives, true negatives, and false negatives when measuring
| accuracy.
| isoprophlex wrote:
| Going through something like this is very VERY stressful.
| When you get a negative you immediately forget about it.
| When you get a positive you die inside. Speaking from
| experience here.
|
| 84% wrong sounds, to me, as an accurate description.
| Experiencing this from the inside out, only the false/true
| positive ratio matters. (Given sufficiently low false
| negative rates, of course)
|
| 84% of people whose world is turned upside down are
| actually getting a wrong diagnosis.
| [deleted]
| andreilys wrote:
| You're talking about precision (true positive / true
| positive + false negative) but that's only one part of
| the story.
|
| There is a real human cost to having a child born with a
| rare genetic disease (and I would argue is immensely more
| stressful). You can easily adjust the sensitivity to the
| test but at the cost of detecting actual true positive
| cases. The correct response to receiving a positive is to
| do another test to ensure it's not a false positive.
|
| To say 84% wrong is clickbait and used to elicit a
| legislative response (FDA regulation), which will help
| the reporters career.
|
| The actual ratio to tell if something is "wrong" is
| accuracy (True positive + true negative) / (true positive
| + true negative + false positive + false negative)
| mnw21cam wrote:
| No, precision is true positive / (true positive + false
| positive).
|
| Your first equation is sensitivity.
| fshbbdssbbgdd wrote:
| If you get a negative result and then your child is born
| with the condition, you won't forget quickly either.
| SpicyLemonZest wrote:
| I really feel it's an accurate description. If you get a
| positive result on the test, there's a 16% chance your
| fetus has a 1p36 deletion and an 84% chance they don't.
| halpert wrote:
| As you said "if you get a positive result". It's true, if
| you ignore the 99.9% of the time the test is correct
| (true negative result), then you can say the test is 84%
| wrong.
| SpicyLemonZest wrote:
| 84% of people who got a positive test result will end up
| telling their family "it's OK, the first test was wrong,
| my baby doesn't have a 1p36 deletion after all". The
| 99.9% of other people who got true negatives are
| important from a test design perspective, because
| specificity is closer to the actual levers you can pull
| on, but it's not super relevant to the decisionmaking
| process of someone who gets a positive result.
| andreilys wrote:
| Ignoring all the true and false negatives which
| themselves are markers of how accurate the test is.
|
| 16% precision is the correct statement, saying the test
| is wrong 84% of the time implies that those getting
| negative results might actually have positive results.
| robbedpeter wrote:
| He framed his statement correctly, limiting his
| observation to the condition that the test returned a
| positive result. Saying that 84% of positive results are
| false is correct if only 16% are true. You'd need to know
| false negative rates and base occurrence rates (modified
| by whatever other factors are unique to your situation)
| to inform the nature of information you get by performing
| the test.
| treis wrote:
| This seems to miss the point entirely. Even for their worst
| example the odds of the fetus having it go from 0.005% to 7%.
| That's valuable information even if it's not perfect or somewhat
| hard to understand.
| inglor_cz wrote:
| This would be valuable for running some extra tests (possibly
| more expensive, but more accurate), but not for, say, decision
| to abort the kid, which is what usually "hangs in the air"
| after such a test result.
| sjckciodjcr wrote:
| NIPT is not supposed to be used for termination decisions. A
| positive is meant to be "your baby might have this, test
| further with amniocentesis".
| inglor_cz wrote:
| The article in NYT nevertheless states:
|
| "A 2014 study found that 6 percent of patients who screened
| positive obtained an abortion without getting another test
| to confirm the result."
|
| Maybe people aren't informed enough. It is my experience
| that some doctors tend to cut conversations short and some
| people are shy/insecure enough not to pry answers out of
| them.
|
| In this case, that would be a tragedy, given that
| statistically 5 of those 6 aborted fetuses were healthy.
|
| Edit: I found the following comment in the comment section
| of this article, which appears to address the same issue:
|
| _I am a physician with a PhD in Biomedical Informatics.
| Most patients who receive these tests do not see a maternal
| fetal medicine doctor or genetic counselor, and no one
| actually explains that the tests they are receiving are
| "screening" or "diagnostic." Your opinion that this article
| does a disservice to patients reflects your unrealistic
| assumption that most of the doctors ordering these tests
| are actually communicating effectively with patients (or
| frankly, even understand the tests themselves). In my
| experience, they usually aren't /don't. Articles like this
| "fill the gap" on patient education when doctors are unable
| to explain math and risk (i.e., most of the time)._
| sjckciodjcr wrote:
| That's a tragedy. Maybe there needs to be regulation
| requiring results are delivered by genetic counselors
| rather than physicians. Or maybe this is willful patient
| error.
| treis wrote:
| That depends on the person though doesn't it? I'm not sure
| what I'd do in that situation. But 7% seems awfully bad odds
| for painful and debilitating life.
| giantg2 wrote:
| I guess that depends on the exact scenario. There are
| likely people with a variety of conditions who enjoy their
| lives vs having not been born. It brings up a seemly
| logical contradiction that we terminate fetuses
| (potentially viable in some cases) on the assumption that
| they don't want that life yet we don't allow people who
| want to kill themselves to do so.
| rflrob wrote:
| There's a lot of sibling comments going on about whether the
| value they're looking at is the right one. What the Times is
| showing as their headline number is Positive Predictive Value
| (True positive/(TP+FP)), which depends on the prevalence in the
| population. The "methods section" here is a little vague, but
| given the low prevalence I'm willing to accept on face value that
| it's basically accurate (i.e. that it's not assuming that the
| families getting these tests are not orders of magnitude more
| likely to be positive for these diseases). If the test result
| truly said one patient's 'daughter had a "greater than 99/100"
| probability of being born with Patau syndrome', then that's
| concerning, but given the fairly narrow quotes around the number,
| I'd suspect that what is _actually_ on the test result is not
| inconsistent with the fairly low PPV on these screens.
| hprotagonist wrote:
| Behold, the curse of Reverend Bayes:
|
| https://en.wikipedia.org/wiki/Bayes%27_theorem#Drug_testing
| inglor_cz wrote:
| Interesting.
|
| We have been undergoing IVF with my wife since 2019. (Covid made
| a huge mess of those plans...) One of our embryos tested as a
| possible positive (but only slightly) for aneuploidy of one
| chromosome.
|
| The doctor, a veteran of IVF, looked at the results and said "my
| experience is that this is either a very small mosaic error,
| which tends to be utterly invisible in real life, or a computer
| artifact. I have never seen embryos with those borderline results
| develop any serious problems later. Things would be different if
| the aneuploidy signals were clear, but definitely do not discard
| this embryo".
| isoprophlex wrote:
| Good luck, keep up your hope. I hope things work out for you.
| sterlind wrote:
| I've heard that in the early days of HIV, the tests were (e.g.)
| 95% accurate, and when patients saw their positive results and
| the supposed 5% chance it's wrong they'd sometimes kill
| themselves.
|
| They revised the tests so the first test would say Inconclusive
| rather than Positive, and ask them to repeat it. This saved some
| lives.
|
| Maybe this a UX failure? Shouldn't the test designers present the
| results like this, even to doctors?
| adjkant wrote:
| Absolutely a UX failure here, one that it seems some doctors
| translate for patients while others are left in the dark on.
| From the way people are responding on here about the use of
| statistics in the article, it's clear that a big portion of the
| techo community I think is undervaluing that often UX is far
| more important than it is treated.
| tambeb wrote:
| A tweet about this very article caught my eye yesterday, and I'm
| glad HN's taken notice too.
|
| https://twitter.com/JohnFPfaff/status/1477382805583716353?t=...
|
| 'For a disease w a 1-in-20,000 risk, a test w a false positive
| rate of 1% and a false negative rate of 0%--an insanely accurate
| test--would identify 1 correct case and 200 false positives every
| time. Or would be wrong 99.5% of the time.
|
| This isn't "bad tests." This is... baserates.'
| Neil44 wrote:
| Before my daughter was born I sometimes felt like it was the
| doctors job to scare us with every worse case scenario possible.
| It was quite stressful and upsetting.
| middleclick wrote:
| I had rather my doctor be upfront about all possible scenarios
| than to be try and nice about them and save possible
| information.
| kingkawn wrote:
| The point of the profession is to find and address bad outcomes
| before they happen.
| lostlogin wrote:
| I'm not certain that perk of parenthood ends at birth.
| neonate wrote:
| https://archive.is/LEWoE
|
| http://web.archive.org/web/20220102044133/https://www.nytime...
| csours wrote:
| Edit: They kind of do this farther down in the article.
|
| Considering this as a UX challenge - imagine a grid of 10,000
| dots (100x100).
|
| Draw one box around the base rate - the rate at which you expect
| to find the problem in the population. If the base rate is 1%,
| then the box is 10x10 = 100 dots.
|
| Then color in the dots for the test positive rate (not false
| positive, just all positive tests) False positives would be the
| colored dots outside the box.
|
| Next to that, put strikes through the dots corresponding to your
| expected false negative rate.
| taeric wrote:
| This is an example of a problem that is so hard to explain. The
| vast majority of folks getting these tests will get a true
| negative. Such that for most people, this is not an issue. So I
| get that it takes effort to make people care.
|
| That said, I do feel that pulling in abortions to the debate is
| specifically to trigger a set of readers. But to what aim? They
| have not established that the tests could be better. Just that
| when they say yes, they are still not perfect.
| siganakis wrote:
| My wife and I went through this a couple of years ago, with a 10
| week NIPT calling a rare trisomy (chr 9), which is always fatal
| within a few weeks of birth.
|
| It was absolute hell. The key problem here is the waiting and
| uncertainty. You have the NIPT at 10w, but you can't have the
| amniocentesis until several weeks later. When that came back
| fine, there were questions about whether it was a "mosaic"
| meaning only a small proportion of cells are effected. We were
| only really in the clear after the 20 week ultrasound.
|
| That's a lot of weeks to be consumed by wondering about whether
| to terminate the pregnancy, or wait it out for more information.
| I have a masters in bioinformatics (in genomics!) and my
| knowledge of stats and the science was next to useless in the
| face of these decisions.
|
| I know of couples who simply couldn't deal with this uncertainty
| and chose to terminate on the basis of this test alone.
|
| Fortunately for us our child was fine and is a perfectly healthy
| 18 month old now, but I wouldn't do the rare trisomy test again.
| bjt2n3904 wrote:
| So glad to hear that things turned out well for you and your
| family.
| tinbad wrote:
| Having gone through two twin pregnancies (where the odds of
| these tests being correct are especially low) we declined all
| of them. Anecdotally, I know of several parents who had a
| positive test for genetic disorder, went ahead with the
| pregnancy anyway and children were perfectly healthy. Until
| these tests are close to 100% reliable I don't see the point.
| raymondh wrote:
| Thank you for sharing this.
| subpixel wrote:
| Our experience was kicked off by a troublesome ultrasound and
| then confirmed by amniocentesis.
|
| The tragedy of receiving news like this is probably fathomable,
| but I think it may be hard to grasp the emotional and
| intellectual agony of deciding whether to terminate a pregnancy
| based on a set of probabilities.
|
| It breaks my heart to think that parents face this decision
| with erroneous data.
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