Here’s why it’s a good idea for everyone to understand a little basic statistics.
Stacie Chapman’s heart skipped when she answered the phone at home and her doctor — rather than a nurse — was on the line. More worrisome was the doctor’s gentle tone as she asked, “Where are you?”
On that spring day in 2013, Dr. Jayme Sloan had bad news for Chapman, who was nearly three months pregnant. Her unborn child had tested positive for Edwards syndrome, a genetic condition associated with severe birth defects. If her baby — a boy, the screening test had shown — was born alive, he probably would not live long.
Sloan explained that the test — MaterniT21 PLUS — has a 99 percent detection rate. Though Sloan offered additional testing to confirm the result, a distraught Chapman said she wanted to terminate the pregnancy immediately.
The test may have a 99% detection rate — if the fetus has a trisomy, there’s a 99% chance it will be picked up by the test — but what also matters here is the false positive rate. How often does the test say the fetus is trisomic when it’s normal and healthy? They don’t say.
The companies marketing these tests are overselling their virtues, and some of the medical professionals recommending abortions after positive results don’t seem to understand the concept of false positives, which is shocking.
Another standard example of a test made useless by a high false positive rate is the Prostate-Specific Antigen (PSA) test, which isn’t even recommended for routine screening any more — too many healthy men were getting flagged by the test as potentially carrying prostate cancer, and were then given biopsies or even surgery.
The PSA test may give false-positive or false-negative results. A false-positive test result occurs when a man’s PSA level is elevated but no cancer is actually present. A false-positive test result may create anxiety for a man and his family and lead to additional medical procedures, such as a prostate biopsy, that can be harmful. Possible side effects of biopsies include serious infections, pain, and bleeding.
Most men with an elevated PSA level turn out not to have prostate cancer; only about 25 percent of men who have a prostate biopsy due to an elevated PSA level actually have prostate cancer.
Only 25%! That means that if you get a positive PSA test, odds are better that you don’t have prostate cancer than that you do.
That’s bad enough that you’d suffer through a biopsy because of a sloppy test…but imagine if you’d aborted a healthy and wanted fetus because a test was that useless.
A wonderful illustration of Bayes’ Theorem at work!
They claim a specificity between 99.9% for trisomy 21 and 99.6% for trisomy 18 :
information for providers
No idea how realistic that is, I didn’t have time to look at the studies.
Everyone involved in screening should read this brilliant blog post by David Colquhoun: On the hazards of significance testing. Part 1: the screening problem. There’s no complicated maths, but there are some basic concepts about screening tests that should really be more widely understood:
@originalantigenicsin
But even this number does not tell you enough because you also need to know the prevalence of the disease to get the correct result.
Assume 1 fetus in 1000 has trisomy and the false positive rate is 99.9%.
Out of 1000 fetuses, 1 will have trisomy (and this will be detected with 99% accuracy) and one is false positive. So the actual numbers are 50:50.
According to the 100% reliable wikipedia, the incidence is 1 in 6000. This means that the actual likelihood was about 16.5% that the child had the disease. I feel so sorry for her.
My primary care physician and I had a good discussion about PSA tests, and other tests for major illnesses in general. The takeaway was that any time you get a result that indicates a serious problem, you should immediately re-test with a new sample and preferably with a different testing methodology (if it’s available). Only after receiving a confirming indication should you take steps.
@originalantigenicsin The prevalance of Trisomy 21 is ~1 in 1000 . So that would mean if you screen 10,000 women there would be 10 cases. With a 99% sensitivity you would pick up 9.9 cases. With a 99.9% sensitivity you would get 9.99 false positives – so there’s a roughly 50% chance that a positive result is wrong. Presumably an amniocentesis would be done as a follow up.
Chapman’s reaction surprises me. Call me an optimist or call me delusional, but faced with news like that, I would probably go into heavy denial at least long enough to get the call back. Even if I hadn’t considered false positives, the samples could have been switched. The labels could have been misread. Who knows? I would come up with a long list of reasons why this cannot possibly be happening to me before considering any course of action.
Of course, people have different reactions, and the false positive rate should be presented and explained for any screening test. This is true for the Down syndrome screening tests that can be used to decide whether to go forward with amniocentesis.
On topic for false positives, but not for medicine: Drug-sniffing dogs. I’m sure they’re quite good at detecting drugs, but only if those drugs are actually present. Otherwise, they give a lot of false positives because they like to please their handlers who happen to want excuses to search people they don’t like.
I’m not like that, frankly.
See also racial profiling.
I like to think my denial is mitigated by a large amount of self-awareness that it is happening. I never suggested that everyone reacts the same way.
It seems like it’s also important to know if the false positives are random or systematic. If the false positives are random, then taking the test again and getting 2 positives in a row would be fairly strong evidence for having the disease. But if the false positives are systematic (for instance maybe I just naturally have high PSA levels but am perfectly healthy) than I can take multiple tests and all of them will give a false positive, making multiple tests not useful.
Bayesian statistics can be very nonintuitive. I read a book about it many years ago and it was eye-opening how many seemingly important things could be explained as random variation in a huge population. A tiny fraction of a huge population can still be a large number of people.
I have always assumed that the false positive rate of screening tests is systematic. Otherwise, these would be much more powerful tests than they are usually made out to be. I.e., just take several blood samples at different times and only report the combined results. Surely, it cannot be that easy.
In Chapman’s case (BTW, she did not follow through with the abortion, and the baby was born healthy) I would think the next step would be a more definitive test. I am not sure what the screening test looked like, but couldn’t they have followed up with amnio? Couldn’t that detect Edward’s syndrome? Normally, you avoid amnio unless indicated, because it increases the risk of miscarriage, but it is less drastic than terminating a pregnancy based on a screening test.
Quite frankly, knowing nothing else but that the fetus has an approximately 1/4 or 1/6 chance of having the disease, I would probably abort and try again. It’s not worth the risk.
Of course I never have to actually make that choice, so it’s rather easy for me to speak.
Jacob Schmidt #15
This is a false dichotomy. The screening test mentioned in the article is MaterniT21 PLUS, and if you look it up, you see it is a non-invasive blood test with limited diagnostic power. You can follow up with a more invasive, more powerful test such as amnio. From the website itself:
So the next step after a positive test result is to get actual fetal cells from CVS or amnio. This will provide a definitive result (well, honestly I do not know the false positive rate from amnio, but I think it is pretty low).
While it is certainly ideal for patients to understand the concept of a false positive, I would place the failure on the health care provider in this case. They should be able to provide care to any patient regardless of the patient’s grasp of statistics. Probably it is best to keep it simple and follow a flow chart: This is a screening test. We don’t make any decisions about treatment based on the screening test, but we may decide to follow up with a more invasive test.
Now if the doctor doesn’t understand the concept of a false positive or the purpose of a screening test, that is a real problem.
These tests are incredibly useful in the right hands. I suppose that it the advantage of a public system (Canada)- I counsel everyone that the screening test is a “hey, look over here”, and that a positive result can happen with a healthy fetus. Followup testing for positives includes a meeting with a doctor specializing in medical genetics, a detailed ultrasound at a tertiary care centre, and only occasionally amniocentesis.
I can see a young family with lousy medical insurance weighing the cost of all of that with the cost of aborting and trying again. I can also see aborting because the worry is making you crazy. Or because the followup testing will put you over an arbitrary line wherein you can no longer get an abortion because oops viability. Or whatever. It’s personal, and important.
I saw that, although Ms. Chapman was hysterical, the doctor had her immediately contact another one who scheduled the termination for *the next morning*.
OK, the doctor did call back and strenuously recommend more testing, but whatever happened to “Take a day to think about it. Sleep on it. Wait until your husband gets home (he was out of town) so you can talk it over.”
Time to get a new doctor.
It seems like health care providers really need to understand the false positive rates of the tests they’re using and to properly convey them to patients. A while back my infant son tested positive for pertussis. Not that big a deal, we got a prescription for antibiotics and gave them to him. Meanwhile, I can always attribute this to some unvaccinated yahoo out there spreading it around and my son having only had his first shot for it and not having a strong enough immunity. Maybe that first shot is why his symptoms weren’t very severe. But given that his only symptom was an ordinary cough that lasted a bit longer than seemed normal, and a positive test, I’ve always wondered if it was a false positive, if he never had it at all and the antibiotics were unnecessary. In this case, that’s mostly a matter of my own curiosity, a handful of antibiotic prescriptions for non-existent cases of pertussis aren’t the end of the world. Unless the child has a hitherto unknown allergy to the antibiotic. But in trying to satisfy my curiosity I found that I could not find any information on the false positive rate of tests for pertussis. So I wondered if most doctors know, or even think about it. I can’t imagine what it would be like to get a false positive for something where the intervention had more serious consequences. Oh, and just for kicks I went and looked now to find the information and what’s the first result that pops up? What appears to be an antivax website. So apparently anti-vaxxers are using the existence of false positives to promote their agenda. But that’s just another reason people need to have a good understanding of the statistics.
Ooh, should have read the article in full before commenting, naughty me. We don’t have private companies doing screening, ours is standardised. This looks exceedingly sketchy.
it likely would have created a bit less confusion if PZ included this bit from the article:
so, they kinda DID say what the rate of false positives were. 50%.
it’s poor journalism though, to loosely cite a study and not put the actual numbers in there, so I don’t really blame anyone for missing it.
There was a nice Healthcare Triage video a while ago on Bayes Theorem. It does seem like some practicing physicians could use a review.
Pertussis has an exceedingly low false positive rate as it’s PCR.
agree 100%.
I’ve experienced something like this myself. I was once diagnosed as being Hepatitis C positive. I know how someone ‘gets’ Hepatitis C and unless my dentist was sloppy (always possible) it just didn’t seem to make sense. This is how I actually learnt about Baye’s theorem and the problems of false positives.
The false positive rate for the Hep C antibody test is about 1% (and at the level I tested it is closer to 0.1%). The probability that I had not been exposed to Hep C in my life, more like 99.999%. Further testing for direct presence of virus showed I was negative. But my stupid doctors at the time (general and specialist) insisted that I must have “cleared” the infection (possible but very very unlikely) because they just didn’t understand what the false positive rate means and assumed I lied about not being an IV drug user. It was as if the positive test for Hep C _meant_ I was an IV drug user to them. What does this matter? Well it meant I had a very bad relationship with my physicians which had an impact on trust in both directions. I know, in the end this is really a privileged problem to have; I really did use a plural (physicians) in that last sentence.
I continued to test positive for antibody and negative for RNA for 18 months afterwards. 8 years later I test positive for neither. I feel vindicated and learnt a lot about probability and medical testing which has made for a good teaching example when explaining the concept of Baye’s theorem and false positives. None of this is to say people should ignore test results. But from personal experience I can say some doctors (not my current who are excellent) really have trouble understanding what results can mean or fail to communicate what they really mean to patients. The impact on me in my case was a few months of distress, but for medical misinformation to impact parents wanting children is deplorable.
Also with agree with Ichthyic and PaulBC. And I don’t think it’s that difficult to do. This from NHS Scotland’s bowel screening program:
Jacob Schmidt
Yes, we notice that. Because you’re really quite ignorant about the realities of being pregnant and also getting pregnant. You don’t know if there’s another chance. You don’t know how much emotional attachment she has for this fetus. You don’t fucking know and you never will unless you have been in that situation and that will never happen.
granetstar
Personally, I find a doctor who gives me the facts and then lets me decide myself quite a good choice. Because women really neither need their husbands to tell us what to do with our bodies nor do we need artificially imposed waiting periods because we really can’t be trusted with making the decision to have an abortion.*
*Funny how nobody ever tells you that you shoudl think about an abortion and then come back for counselling a week later to justify your decision to go through with the pregnancy…
+++
IMO, most pregnancy testing is backwards anyway. Instead of starting with a conversation about what a diagnosis would mean and what you’d do in that case, they start with testing. Of course with the low invasive, high false positive tests. And when they get back with a positive result (or a high probability), you get ushered into more invasive testing with a high risk of miscarriage, all this without ever talking about probabilities and disabilities and so on.
Back in my pregnant days the “Tripple T” test was very popular. It took some measurings and bloodworks and statistical values like age of the mother and calculated a probability. At a probabilty of 1:2000 for Trisomie 21 they would recommend more invasive testing, only that those cause a miscarriage in 1-2% of the cases. Which means that if they tested 2000 women, 1 would get a diagnosis of Trisomie 21, which might mean that she would choose an abortion, and 20-40 women would miscarry a perfectly healthy fetus.
When I was having testing done during my pregnancy, the docs explained the specificity and false positive rates to me before even having the test. For my age (35) they recommended the blood test, but clearly stated ahead of time that any positive results would mean more testing was indicated. Since everything turned out normal, I did not do an amnio. The failure here is with this woman’s doc, not the test. The test is just one tool.
This is a timely post for me. I am scheduled to go in tomorrow for a yearly mammogram. Lots of false positives result from that screening test.
still, way too many men get treated for prostate “cancer”. some 90% of men who could qualify for surveillance choose treatment instead and some 80% have sexual dysfunction side effects and some 50% have incontinence side effects. i believe a large part of this is the doctors who have a particular tool (davinci robot, cyberknife, etc) that they have a financial incentive to use. there should be some different name for low-risk prostate cancer to more clearly indicate the likelihood of dying from something else entirely.
@16 PaulBC
I would say the health care provider did her job in this case. She persuaded the woman to undergo a diagnostic test before making any irrevocable decision.
Wow.
I’ve been on both sides of this. With my second child I chose not to have the triple screen, as it had a high rate of false positives, particularly the 20 years ago when I was pregnant. I was 23 and had a healthy child already. As it turns out, despite being in the lowest risk group for having a baby with Trisomy 21 (1-1250) my daughter has Down syndrome.
Because of the unusual type of karyotype my daughter has, I was told my risk was not 1-100 with a subsequent pregnancy like most people, but no more than the general population. I was 26 when I had my son and we watched the pregnancy closely, though I decided against a CVS test since the chances of miscarriage from the test was higher than the risk of a genetic issue. My 18 week ultrasound showed chorionic plexus cysts however, which could be nothing, or could be a sign of Trisomy 18. I had an amniocentesis that day and thankfully all came back well with 46, XY.
I’m not sure what my ramble means just that they need to not oversell these kinds of tests, so much can happen and you need the definitive answers. What may seem to be a normal pregnancy might be something else, what may seem to be an issue may be nothing. Always, always err on the side of caution and encourage second opinions.
Regarding the PSA test and what happens next. This could soon be changing for the better, thanks to recent research
http://www.abc.net.au/radionational/programs/healthreport/prostate-mri—a-game-changer3f/5967568
People are also convicted based on the trust of juries in DNA evidence. There was a recent Australian case where a guy was wrongly convicted. Police had taken a mandatory DNA sample after they charged him with a trivial offense which he actually did not commit and was not convicted for. However his sample was processed at the same time as samples from a rape scene. He was falsely convicted and served substantial jail time when sloppy lab procedures contaminated the samples with his DNA. Can’t find a link to the Australian example but here is a similar incident from the UK.
http://www.bbc.com/news/uk-england-manchester-17460661
Uh, it’s just a fetus, what’s the big deal?
—-Uh, it’s just a fetus, what’s the big deal?—
Why are you so concerned I ran over your pet? It’s just a cat. What’s the big deal?
“Why are you so concerned I ran over your pet? It’s just a cat. What’s the big deal?”
You really can’t see the difference?
A cat is a living, independent being that brings love and light into the lives of its humans, and even contributes to the household via pest control.
A fetus is a parasitic entity that damages its host and contributes nothing to the household.
The cat has more inherent value than a clump of tissue.
WMDKitty @ 35
@ 37
If a fetus is wanted, it’s invested with a great deal of emotion and potentiality. It’s something in someone’s body that they don’t want to lose. Even if it’s not yet an independent person, plans and hopes and dreams are already being made. This is why losing a wanted pregnancy is deeply traumatic for many people.
If you don’t want a pregnancy, obviously it’s completely difference. But being mislead into making a choice about your own bodily autonomy and future that you did not want to make is a big, emotional deal.
You don’t get to make judgment calls on how other people should feel about their own reproductive choices.
WMDKitty,
You are aware that people have different feelings and desires than you? And that different things hurt them?
Think. What are you telling women devastated over losing what would become a wanted and loved child? What are you telling those who can’t even get pregnant but want to? You can be sure it’s not ‘just a fetus’ to them.
Every now and then, when this topic cpmes up, you turn into a raging asshole. You kinda appologize later and do it all over again. Those apologies seem worth less and less as time goess on
WMD Kitty
What beatrice said. Believe me, if you’d told me “it’s just a fetus, what’s the big deal” after I miscarried a wanted pregnancy, I would probably have turned violent. Actually, I almost ruined my aunt’s birthday over some guest making such a remark.
This is completely independent of the fact that I’m adamantly pro-choice and would abort any subsequent fetuses without much of a second thought.
Beatrice
Sure, people have different feelings and desires. Sure, different things hurt them. I’ve never denied this.
As for your other questions:
1 Try again — She didn’t lose an actual child, just the potential of one. Lost potential is sad, yes, but not the horrible tragedy that some are acting like it is.
2 ADOPTION. There are hundreds of thousands of children in America alone who are waiting for a forever family. Any one of them would love to be chosen.
Additionally, I strongly object to the deliberate abortion of disabled fetuses when the disability or defect is not so severe as to be incompatible with life. Ms. Chapman is no better than the Nazis, who made a point of exterminating the disabled. We condemned it when they did it, why should we praise her for doing the same thing on a smaller scale?
Don’t get me wrong here, I’m pro-choice, I support abortion on demand, but I draw the line at the deliberate abortion of a disabled fetus for the parents’ convenience and comfort because it is a form of genocide.
Ms. Chapman is free to wail and moan and cry all she wants over the fetus she deliberately threw away because it “wasn’t good enough”, but she gets no pity from me because she chose to be an ableist bigot.
Just shut the fuck up once in a while, would ya WMDKitty?
NO. I will not shut up, because you guys are essentially supporting the deliberate genocide of the disabled.
WMDKitty,
No time right now for much more than a fucj you and fuck off and why whine about a fetusthat might become a disabled child.. it’s just a fetus you shitty hypocrite.
I’lllink to the (couple of) last times human emotions that differ from yours were expla8ined to you when I get home.
Fuck you too, Beatrice.
According to you, I guess it’s okay to kill when the victim isn’t really a person, just a worthless cripple…
WMDKitty — Survivor #45:
The ‘victim’ is not a person at all. The ‘victim’ is a foetus.
Really? How about if the couple don’t want to make the financial commitment which raising a child involves, or simply don’t want to have a child? Those reasons are just as much ‘for the parents’ convenience and comfort.’ Just how many restrictions are you willing to put on this putatively free choice which you claim to support?
WMDKitty,
Nope, it’s just a worthless fetus. So no killing, just eliminatipn of parasite tissue.
It’s funny how fetus is suddenly a victim once the issue is something you care about.
WMD Kitty
You can’t have it both ways. Oh, I forgot, you’re you, so I guess you can.
+++
To all further assholes who want to claim “it’s just a fetus”:
Congratulations, you’ve joined rank with “pro-lifers” in vanishing the pregnant person from the equation. They go on “it’s a baby!!111!!” and ignore that person, their lives, their health, wishes, desires, existing children and responsibilities, you scream “it’s just a fetus!!!111!!!! and go on and ignore that person, their lives, health, wishes, desires and responsibilities. What if this person tried for 2 years to get pregnant? What if they’re a transman who needs to abstain from HRT for the duration of a pregnancy? What if they carefully timed the pregnancy to suit their careers ad education? What about the fact that second trimester abortions aren’t as easy as pie? What about the psycholgical implication? Nonono, you don’t care as long as YOU can tell this person who is most likely a woman what she should do and how she should feel.
I hope you’re proud of yourselves.
Daz, let’s say there was a genetic test for homosexuality or transgenderism. I’m sure you and many others here (myself included) would loudly object to someone choosing to abort a fetus just because it had that particular genetic combination.
This is no different. It was the deliberate termination of a fetus that was determined to be “less than” because of a particular genetic combination that made it different.
Legally, of course she should have the choice. I don’t want to take that away from anyone, ever.
I think her choice was bigoted and ableist, and is too close to eugenics for comfort.
Try to think about it from a disabled person’s POV for a second — it’s fucking scary to see people go, “oh, my kid might have a disability? Abortion!” because it’s a direct statement that the disabled are less worthy and less than human.
WMDKitty — Survivor #49:
I shall state this very simply.
Someone’s reason for getting an abortion is none of my business. I do not have the right to make the choice for them or to argue that they should not abort. It’s their body, and it’s their life which will be affected by the responsibility toward a child, should they bring one into the world—so it’s their choice whether to do so.
As soon as I say ‘I support free choice except…,’ then I no longer support free choice, do I?
Yeah, because we would all be very happy about forcing a woman to go through with a pregnancy she doesn’t want and then having a child born to parents who obviously hate that child or who would dump that child into the oh so effective foster system (hey, I have a gay black trans child, who’s going to adopt them?). That would truely make the world a better place for gay people or trans people.
You really are like a “pro-lifer”: Instead of focussing on social situations and improving conditions, you focus on the pregnant person and on what they are and aren’t allowed to do and how they are basically evil.
Giliell — Well, of course those things need to be taken into account, but it must also be acknowledged that pregnancies almost never go exactly as planned. Problems conceiving, complications, preterm labor, premature birth, stillbirth, miscarriage… it makes no sense to plan out a pregnancy like you’d plan out a vacation.
“What if this person tried for 2 years to get pregnant?”
Why would anyone keep trying for two years if it obviously isn’t working? Is passing on your specific DNA really that important? Why not adopt? Or just, you know, accept that you can’t have a baby and deal with it?
“What if they’re a transman who needs to abstain from HRT for the duration of a pregnancy?”
Why would a transman ever want to get pregnant anyway? Not that it can’t happen (it has), but I don’t see this being a very common choice. Regardless, you’re still acting like every aspect of pregnancy, from conception to birth, can be planned out in advance.
“What if they carefully timed the pregnancy to suit their careers ad education?”
Then you have to decide what’s more important, and quite frankly I’d come down on the side of careers and education. And again with the “let’s plan this pregnancy like we plan a vacation.” It simply can’t be done.
“What about the fact that second trimester abortions aren’t as easy as pie?”
Nobody said they were, and I certainly wouldn’t expect it to be a walk in the park. BTW, mid-pregnancy, how would they do this? Induce labor? Surgical removal? Then there’s the issue of potential complications from anything from the anaesthesia to the procedure itself to the pain pills you get after…
“What about the psychological implication?”
I’m assuming it’s little different to losing any other loved one, and yes, that’s always a tough thing to go through. Quite possibly more so if you felt “responsible” for their death. I’d say it would be perfectly fair to allow someone who’s had to abort a wanted pregnancy ALL the time and space to grieve their loss.
BUT
None of that changes the fact that Ms. Chapman’s choice was inherently bigoted and ableist.
Daz, I shall state this equally simply.
Try to think about it from a disabled person’s POV for a second — it’s fucking scary to see people go, “oh, my kid might have a disability? Abortion!” because it’s a direct statement that the disabled are less worthy and less than human.
I do believe she should have every right to do whatever she damn well pleases with her body. (Until she’s causing harm to others.)
But I also believe that it is wrong to treat the disabled as anything less than fully human. (Something our society desperately needs to work on.)
Unfortunately, Ms. Chapman’s choice — hers to make, legally — has some really nasty implications for the disabled, and from my wheels, looks an awful lot like eugenics. And honestly, I can see America going down that slippery slope to full on extermination of the disabled. (Especially under Republican rule…)
WMD Kitty
All your arguments are “suck it up and do as I tell you because I know better”
I mean, why would a trans* man want to become pregnant? Gosh, it’s not like you could ask them?
Why would you keep trying and not just adopt?
Well, maybe becaue adoptions are fucking expensive and maybe because you’re not elegible for an adoption and maybe for a dozen other reasons that are none of your business.
And gosh, you can’t plan every aspect of pregnancy and childbirth so how dare you to want control over any aspect.
And behold the horrible crime of a woman wanting to have a career AND children!
Oh, wait, we’ve gone from “just abort it” to “oh, look, mid pregnancy abortions are complicated!”. You’re completely ignorant on the suject, but you also think to know much better than those women who actually are in the situation.
You are, in short, a misogynist.
Well, maybe you could read this
So, a woman not wanting to go through with a pregnancy that would result in a baby who would be doomed to a short and painful life in a NICU is a bigoted ableist. Because NOT wanting to inflict a short existence of nothing but pain on your child is apparently a horrible thing to do. Yeah, that’s compassionate. *spit*
“The companies marketing these tests are overselling their virtues, and some of the medical professionals recommending abortions after positive results don’t seem to understand the concept of false positives, which is shocking.”
Overselling their virtues? No I think they are straight about the limits of their screening test.
I work in the field here in the UK and I have never dealt with any health professional working in PND who doesn’t understand false positives.
In the case above, the woman was offered further testing, probably amniocentesis so the clinician did understand false positives or she would not have recommended further testing.
In the case of chorionic villus testing you are testing the placenta and not the fetus so you do also get false positives due to confined placental mosaicism. So most people now prefer amniocentesis.
What Daz and Giliell said. The fact that sex-selective abortion is a massive issue in some parts of the world reflects the fucked-up low status of women; the direction to strive to go in is to change that fucked-up status imbalance, NOT to restrict women’s choices even further and criticise them self-righteously the while. Exactly the same goes for a hypothetical test for sexuality or actual tests for disabilities.
WMD Kitty you are being stunningly self-contradictory – and fundamentally anti-choice. Women don’t have to choose whether or not to abort for reasons anybody else approves of; I might loathe somebody’s reasons but it’s her choice not mine.
The only person whose feelings and decisions matter here is the pregnant adult; if she doesn’t want to have a daughter/child with a disability/child who is gay or trans* in this or any other shitty and prejudiced society, I hate that the society is shitty and prejudiced but that is her choice – to seek to limit that is to say ‘well, sometimes it’s ok to be a forced-birther really’. No, it’s not ok.
And yes of course it’s a blob of cells, so what? That is not in contention here. What matters is the distress of a formerly-pregnant adult who wanted that pregnancy, if they did want it; your comment is open to criticism not on grounds of factual accuracy but on grounds of being an arsehole move.
“If her baby — a boy, the screening test had shown — was born alive, he probably would not live long.”
See, now THAT changes things. If he had a condition that was incompatible with life, OF COURSE the kind thing to do is abort! Think you could have mentioned that earlier instead of waiting until now? Or hey, maybe even just pointed me to the relevant passage, instead of attacking me? Or are you getting your jollies attacking someone who you know FULL WELL is on YOUR SIDE?
Asking questions out of genuine curiosity is not misogynist. I’m familiar with early abortions (usu. chemical or suction) and extremely late term abortions (usu. induction of labor), and am not sure what they would do for an in-between abortion, SO I ASKED. I’m not sure why a transman would want to go through the hell of pregnancy and childbirth, SO I ASKED. (And if he does want to go through it, more power to him.)
Why?
BECAUSE THAT’S HOW PEOPLE LEARN NEW THINGS. BY ASKING QUESTIONS.
So please, take your outrage and anger out on someone else instead of the person who is actually trying to figure shit out.
WMDKitty — Survivor #53:
Or it could be that raising a disabled child requires heaps more commitment of time and money and could quite possibly be much more of an emotional roller-coaster, than rearing a child who isn’t disabled; any or all of which the woman/couple might not feel themselves able or willing to cope with. Or, as in this case, it could be that the child would face a short and painful life which they do not wish to inflict upon a child.
I agree. Two things. One: that feotus is not a disabled person, or a person at all. More importantly, two: If we stipulate that it is, it still doesn’t have the right to demand the use of another person’s body.
See my first paragraph.
opposablethumbs
For the last fucking time, I AM NOT TRYING TO RESTRICT HER CHOICES. I am trying to point out that her choice — HERS, LEGALLY AND MORALLY — has unfortunate implications for the disabled.
OF COURSE we need to change society! No argument here!
But can you able-bodied people please stop judging me for pointing out a VALID ISSUE?
PS I take you point wrt abelist prejudice in society, WMD Kitty, but criticising a woman for choosing abortion – for whatever her reasons may be – is not the way to go.
K, guys, last post for the night, then I’m out.
“Or it could be that raising a disabled child requires heaps more commitment of time and money and could quite possibly be much more of an emotional roller-coaster, than rearing a child who isn’t disabled;”
Yes, and a parent should be willing to make those sacrifices for their child.
“any or all of which the woman/couple might not feel themselves able or willing to cope with.”
Help is available for parents of disabled children. Everything from support groups, to counseling, to respite care to give the parents a break. And having seen what some parents have had to deal with (from my own family and others), no, it’s not “easy”, but it’s not the end of the world, and it’s not going to kill them to care for a disabled child.
“Or, as in this case, it could be that the child would face a short and painful life which they do not wish to inflict upon a child.”
The phrase “incompatible with life” comes to mind.
Now, seriously, I’m out for the night.
Uh, it’s an unreliable medical test. What’s the big deal?
Whether or not it’s an actual or potential anything, that has fuck all to do with her autonomy. And the latter is why abortion is acceptable, as well as actually being coherent and making some principled distinction about reality instead of “potentiality.” If you’re not clear about that, I’m not sure we can have a coherent conversation about this at all.
This kind of misleading test has the effect of taking away her autonomy, which she should always have, independently of whatever the fuck there is inside her body or what there may or may be in the future. You cannot make a reasonable and responsible choice (whether to keep it or not to keep it) on the basis of such unreliable and misleading information. This is not something which women should have to face, certainly not because of your confused paranoia about its supposed connection to bigotry or ableism. It is the responsibility of the medical establishment to do better.
Edwards syndrome, via wiki:
You seriously believe someone is a “bigot” or an “ableist” with regard to people who don’t even survive, or who have problems like these? It’s much more reasonable to think they’re concerned about reducing (or altogether preventing) the suffering their child would experience (and perhaps reducing the mother herself). I cannot see how it could have a fucking thing to do with being prejudiced or discriminatory toward people who experience such problems, especially when they can’t know what the fuck is actually going on in the first place.
WMD Kitty
We’re judging you for being an asshole.
So far you have co-opted LGBTQ people for your argument and you have not given one shred of thought about the person who is pregnant and want her to have to think about you first and herself last, even though going through with the pregnancy (had the diagnosis been correct) would not have resulted in the birth of a person with a disability, but in a stillbirth or the birth of a baby who’d have died shortly afterwards, suffering.
You’re argument is basically “what if your mum had aborted you?!?”
BTW, I would have been one of those horrible people. When I was pregnant with the little one we found out that something was wrong with her kidneys and for some time the jury was out between “she’ll have one functioning kidney and this will hardly impact her life” and “she’ll have Potter’s Syndrome. Should she survive birth she’ll suffocate”.
Fortunately, it was the former, but had it been the latter I would have chosen an abortion, a choice that although I would be unfortunately still entitled to make would also make me a horrible ableist bigot according to you.
You’re not trying to restrict her choices, yet you said..
Mayhaps you incorrectly used the phrase, but when someone draws a line, that typically means that they will support something up to that point, but NOT support it after… which means that you think her choice should be restricted.
If a person in unable financially or emotionally to deal with a disabled child they should not be forced to, nor should they be looked down upon. Do you look down on me because I choose to have *no* children? I would abort if I got pregnant, whether it was healthy or not, because I am NOT good parenting material on pretty much every front.
Does this make me a Nazi, like you claimed for the poor woman who you “just a fetus’d” but then said is committing genocide? You can’t have that both ways, you know. Is it just a fetus, or is it genocide?
Sorry: “perhaps reducing the risk to the mother herself.”
But now, amidst the all-caps nonsense, I’m gathering that some facts weren’t understood and have maybe been sorted out. Maybe. A little.
WMDKitty — Survivor #61:
I completely agree. If one decides to bring a child into the world, one is tacitly accepting certain responsibilities. And one reason for making abortion freely available is so that those who feel unable to take such responsibilities may avoid bringing a child into the world.
WMD Kitty
In short, you are a forced birther.
Because you want to draw the line where it is morally acceptable for a pregnant person to abort. Their reasons have to pass your judgement, you deem yourself fit to evaluate their lives, resources, emotional states and know them better than they do. And lastly you give a fuck about those children. Because if you did you would understand that it is not good for them to be born to parents who do not believe that they can raise and support them. You think that they should be able to do so, that there is enough support and that those are sacrifices they have to make, whether they like it or not. In other words, you sound exactly like the Republican party and all the people who picket abortion clinics.
WMDKitty, #59
Which disabled? The ones that exist as living, breathing humans? In what way does her choice have an unfortunate implication for them? You need to expound on that to get your point across.
PS: Giliell — you were right to call me out. Still don’t much appreciate being called a misogynist, though.
WMD kitty:
“It’s just a fetus, so just grow the fuck up and get over your emotional response to losing it, who cares.”
Meanwhile, you are making a huge stink about YOUR emotional response to what it turns out were not the actual reasons why somebody else chose to terminate her own pregnancy. Hmmm…..
By the way, i agree, it’s just a fetus…nobody needs a reason to terminate a pregnancy other than “i don’t want to be pregnant”. Any additional reasons to do so are all valid, because they are built on the grounds of bodily autonomy. If somebody wanted to abort a fetus on the suspicion that it might turn out to be gay, i would think that’s a bloody ridiculous reason to abort, but it’s still that person’s choice and it has fuck all to do with me. Furthermore, personally, there are situations in which i would have no personal objections to that person’s choice. I think not wanting to have a gay child in an intensely homophobic society is actually a kind choice. Again, this is just a personal thing and it’s not because of self-hatred, it’s because if you could prevent suffering before there is any actual person that can suffer, i consider that a good thing. The problem there is the homophobic society, not the loss of a fetus on any grounds. What you need to work on is creating a society in which nobody would face any adversity because of their sexual orientation. That is, however, very different in the case of certain disabilities, as the adversity is a direct, inexcapable result of the disability itself. You can work on society’s attitude towards disabilities, but that won’t make the disability go away.
@62 consciousness razor
At the risk of derailing the conversation which now appears to be going on – it is NOT an unreliable medical test. As screening tests go, it is actually very reliable and represents an advance in prenatal diagnostic tests because it can be carried out early in the pregnancy, has a higher specificity and sensitivity than other such tests and has no risk of miscarriage. There is no evidence that this woman’s doctor didn’t offer the test appropriately nor that she wasn’t counseled appropriately. The folks trying to make a big deal about the so called unreliability of this test are the right to life crowd.
You are right Chris.
Non invasive prenatal testing is superior to other screens in terms of having a very low first positive rates, high positive predictive value, and high sensitivity. But NIPS is still an alternative to other screening tests, not to amniocentesis or CVS.
Screening just gives you a risk 1:2 or 1:1000 or whatever of your fetus having a certain abnormality. Most women appreciate the information and if they don’t agree don’t have to have screening.
—-You really can’t see the difference?
A cat is a living, independent being that brings love and light into the lives of its humans, and even contributes to the household via pest control.—-
The difference is you like cats and hate babies, which is why I used that particular metaphor.
A pregnancy can bring light and love into the lives of the people involved, but you don’t give a shit, because it’s a potential baby, not a cat. And you don’t like babies, so you are unwilling to wrap your mind around the idea that other people may have an emotional attachment even to a child that has not yet fully come into the world.
Losing a wanted pregnancy is devastating. I mean, the physical side effects you go through, even in just the first trimester – going through that to no result fucking sucks. And when you add emotions into it, hopes and dreams, it’s a million times worse. You aren’t ‘losing a pregnancy’, you are losing a dream, having a hope crushed. It can be devastating.
So, to sum up, fuck you and knock off the trolling.
—-But can you able-bodied people please stop judging me for pointing out a VALID ISSUE?—
Oh for fuck’s sake. You got called on your callous remark, and your response is to try to turn it around and make the people calling out the horrific thing you said into the bad guys? Grow up.
You didn’t ‘point out a valid issue’. You scrambled around after making yourself look like an asshole, backtracking until you could invent to try to justify your asinine remark. And now you are making fucking stupid and insulting assumptions rather than just own up to the simple fact that you said something rude, callous, and horrific.
The first rule of holes is this: when you find yourself in one, stop digging. I suggest you follow that advice.
WMD Kitt
Fine, whatever, I don’t care.
Because we’re not the personal “educate WMD Kitty when she’s talking horrible shit again” brigade. It’s not the first time you enter a discussion about pregnancy, reproductive health, childbirth and childcare, insert your foot firmly into your mouth, keep digging digging digging until you notice that you’re wrong, usually after having caused a lot of harm and damage.
Experience alone should have taught you to STFU on those issues. I don’t care about apologies (not that you’d apologised), I care about people not repeating their behaviour. Changing your PoV is a good thing, but if it doesn’t teach you to think for 5 minutes before yu go out hurting people the next time, it isn’t worth shit.
You don’t appreciate being called a misogynist? Well, maybe you stop behaving like one.
Some of the comments make it clear that not everyone has read the whole article. To cut to the chase, she eventually did not terminate her pregnancy (some comments suggest otherwise). However, healthy fetuses have been aborted based on similar tests.
I agree that the doctor made an attempt to offer additional testing from the start (because it says so even in the quoted part). But clearly something didn’t click until the last minute:
There is probably a clinical lesson to be learned here, though I will leave it to the experts. It is not that we can reasonably expect everyone to understand statistics (but wouldn’t that be nice). It is probably a question of communication. Even with the best of intentions, the doctor did not deliver the message effectively. Perhaps the phone call about these test results should come from a genetic counselor trained specifically to help the patient interpret the test appropriately and not panic.
WMDKitty @ 49
Well, we all make decisions about whether or not we’re going to have children and we should make those choices so freely deciding not to have a child can’t be eugenics in your worldview. If that were the case, all of us using birth control or not having reproductive sex to avoid having children would be eugenicists. Since you’re childfree and don’t identify as a “Nazi” as near as I can tell, I assume this isn’t your worldview.
It must be an outside force pushing one to make a decision that makes it eugenics, right? Taking away people’s reproductive choices or pressuring them to make certain choices. “The state compells you to abort, because ew disabled fetus” would fit the bill of negative eugenics.
…oh, shit. But wait. Scroll down a little further on that page and you see a thing called “positive eugenics.” What’s that? Positive eugenics is where instead of trying to prevent people from reproducing you’re encouraging them to do so. So, for example, telling people who are pregnant and suspect disabled fetuses that they must give birth.
Shaming them and calling them assholes and turning them into birth machines to keep pumping out a specific type of person? That’s far more like eugenics than them making a private choice with their doctor’s input. ‘Cause eugenics is about controlling other people’s choices.
No one is required to give birth for your benefit, WMDKitty.
WMDKitty #41
It certainly isn’t anything like genocide. WTF… how did you even arrive at that? Are they going around killing disabled people in their country?
Secondly, a person owes nothing at all to any group (disabled, homosexual, black, etc) no matter how bad they have it in life solely because they have a fetus inside them that would develop to become a member of that group. Nothing at all. There simply is no connection there.
Just what is the terrible implication such an abortion will have for disabled people? Just what harm is done to disabled person A if a person B somewhere aborts a pregnancy because they would have had a baby with a disability?
I’m taking anything more I have to say to WMDKitty on this topic to the Thunderdome.
Your own previous comments explicitly criticize abortion of fetuses diagnosed with “disabilities not incompatible with life.” The disability for which Ms. Chapman received a false positive result from blood testing is, as noted in the OP, incompatible with life.
Try it.
I myself discovered that if you show up to an ER complaining of itching and jaundice, they will also use that to automatically assume you are an IV drug user.
profiling in the medical industry is a BIG problem that doesn’t get nearly as much media attention as it should.
then you don’t support abortion on demand. simple as that.
you’re obviously conflicted. suggest you resolve to clarify for yourself.
There is a legitimate anti-eugenics argument to be made, and an important concept to keep in mind with topics like this. That is: given that there is a limited amount of resources in the world at any one time, said resources should be spent first on making society/life easier for people with disabilities, and only then spending resources on identifying/curing/eradicating said disabilities. There’s then another argument about what happens when getting rid of a disability is the most common route – let’s say that early identification is easy, and most people then abort. What happens to someone who then is born with that disability? Are their parents considered monsters? Are they considered pariahs? Are we then headed to the Twilight Zone episode “Number 12 looks just like you”? Does society then turn on them for daring to be alive, and refuse to offer them any help at all? But that’s a larger cultural argument, not one that works when scaled down to an individual woman making that individual choice.
WMDKitty
Really? It’s someone else’s responsibility to make sense of the article for you? You didn’t know what Trisomy 18 was and it didn’t occur to you to maybe look it up before you assumed it was just like a hangnail, and that’s someone else’s fault? Before calling the mother an ableist bigot with NO information on the actual choice she had to make? Yeah, what a bunch of assholes everyone else is……
exactly.
PSA is still a good test, when it’s negative. The false positives will be curbed in the future because MRI is becoming the gold standard before any invasive procedure gets done.
Also, ignore the base rates and pre-test probabilities at your peril. Biochem results always have to be seen in a context with base rates, family history(genetic risk), clinical picture and degree of positivity of a test(say, marginal raise vs through the roof level).
I heard a vaguely related programme on Radio 4 the other day. People with genetic disabilities were debating the issue of whether they would use the (available on the NHS and perfectly legal for those with such disabilities) tests to detect whether their fetuses would share their disability. The gist of what one woman (who had such a test and IIRC aborted one fetus and later carried one which tested negative for the specific disability concerned) said was that although she didn’t think her disability made her any less valuable, she’d rather its line in her family (her father and grandfather shared it) ended with her. The presenter said that although she wouldn’t choose to have such a test for her genetic disability, that was her choice and she was glad the option was there for those who chose otherwise.
Embryos aren’t children. If you’re in a position where pregnancy is relatively easy to achieve, then, IMO, screening an embryo and electing to abort and try again is equivalent to deciding whether your child should have the quality screened for. Whether or not you have a disability yourself, if you could choose (by magic) whether or not your child would have a disability, I’d guess most people would opt for “not”, since life with a (severe) disability is undoubtedly more difficult. This is a different question from asking whether a person wishes they had been born without their disability: although many will say yes, others will say their disability is part of what has made them the person they are, and they wouldn’t want to change that.
Here’s a comparison. Many people were severely affected by polio, to the extent of having serious disabilities if they survived. Was the eradication of polio wrong because it devalued those people whose disabilities stemmed from it? If we accept the proposition that fetuses are not people (and I think that’s an uncontroversial assumption round these parts), how is reducing the incidence of a genetically transmitted condition by electing to carry fetuses to birth selectively any different from this? How does ensuring fewer people have to live with a debilitating condition make any judgement on the worth as people of those who already live with it?
People with disabilities are just people. Some are admirable, others are arseholes. Just because I’d rather my kids didn’t have to live with disabilities doesn’t mean I don’t want them to be just like some people in all respects other than sharing their disability. I’m genuinely interested (as a non-disabled parent with another on the way) to know if those of you with disabilities think this attitude is ableist – am I disparaging your worth as a person by saying that you’re fantastic, and I want my next kid to be just like you in every respect bar sharing your disability? Is this going into the defecit model of disability?
Been hesitating to weigh in here for reasons that will become clear, but, anyway.
One of the reasons that I’m certain I will not go through with any further pregnancies is the very high probability of another child being like the two we already have: that is, high-functioning autistic. I cannot do it again.
Those who remember other posts of mine will know that I don’t see those with autism as lesser; I’ve been known to say that it’s a good thing both my boys are on the spectrum, since I understand them better than I would understand children who weren’t. But when they were younger – how do you explain social interaction if you have never been entirely solid on it yourself? How do you encourage socialization when the prospect of casual conversation with another adult makes you want to hide in the bedroom and lock the door?
With all the best will in the world a parent is still a person with their own limitations. Some of them don’t start from a place of infinite resources.
Likelihood ratio’s and predictive values for the win. Sensitivity and specificity are cool and important, but I’m inclined to think they are of very little use to patients and give rise to a boatload of misconceptions.