For one, according to the article the discrepancy was found to be up to 8 points in some cases, not 3. And it seems reasonable that quick, practical decisions in hospitals are made based on point thresholds, not purely huge point leaps as you suggest.
I haven't dug any further than the article and your comment to verify these facts. But rather than find a way to prove why this doesn't matter, why don't we assume it does? Then the knowledge and awareness might spread a little bit more through us, and if it is an issue, it might be that much more likely to be solved. There's no penalty for being wrong with a weakly held but well-meaning assumption. At the very least, we can be more aware of another possible dimension of bias in technology.
Because it should be casually dismissed. This person doesn't know what they're talking about, refused to listen to the people who told them they didn't know what they are talking about, and wrote an article full of nonsense.
If the assumption is incorrect, then it would be misinformation that we would be spreading.
Also, doctors are already aware about how oximeters may be inaccurate. It doesn't mean that they still can't be useful.
First, let's be clear:
> Doctors know that these pulse ox meters aren't very accurate and use them accordingly
Some doctors know...
> Nobody's changing their plan because you have a pulse ox of 93 instead of 95. They're there to quickly measure big changes that indicate a problem.
Sometimes, perhaps even often, they're used for this. It's one use case of pulse oximetry, and it's an important one.
I read your post as extrapolating general claims from common cases, and erasing the real experiences of people that fall outside of these common cases.
Bias often happens at the margins. That doesn't make it less real for the people who suffer from it, even if most people don't suffer, even if the common cases work well.
It can be hard to see those margins when you aren't in them, but that doesn't mean they don't exist -- they are still worth writing about and trying to fix.
As someone else pointed out, this isn't only about melanin in the skin. Darkened skin for any reason will cause this (burns, smoking, dirt, etc...). Medical personnel are trained to account for this partial accuracy.
The other fact is that there are newer techniques being worked on to improve the technology.
Bias doesn't happen in physics. Bias happens where humans and physics interact.
> Medical personnel are trained to account for this
Medical personnel aren't the only people who use pulse oximeters and need them to read reliably. Beyond that, this thread and the article it discusses are full of examples of why "medical personnel are trained" isn't enough of an answer here.
https://scholar.google.com/scholar?q="bias%20in%20physics"&b...
"Cargo Cult Science" (esp. Millikan). http://calteches.library.caltech.edu/51/2/CargoCult.htm
Einstein to M. Curie: https://www.brainpickings.org/2016/04/19/einstein-curie-lett...
Planck: Science advances one funeral at a time. (See also Kuhn.) https://en.wikiquote.org/wiki/Max_Planck
Yes, the way in which varying wavelengths of light interact with varying configurations of bulk matter is a physical phenomenon, and not subject to bias.
But that isn't the same as saying, as the comment to which I originally replied seemed to do, that no bias can exist in the way in which that phenomenon is interpreted by humans.
You sound pretty emotional, maybe tone it down and try to think objectively.
Just because there's an underlying physical reason for the device to be inaccurate on a subset of the population, doesn't mean that it's fair to use that device on the impacted population. It's been accepted by the medical community, despite the additional training required to correctly use the device -- amounting to guesswork when the medical personnel remember that it's necessary. Accounting for human error, this means that affected populations will receive a lower quality of care.
Just a hypothetical. Would it be accepted if it was accurate for black women, and required guesswork when treating white men? Because there is a long history of significant bias in medical studies. Just because "it's just physics" explains the device's flaw, doesn't mean that acceptance of a flawed device isn't a result of systemic bias.
This is absolutely bias, and it is entirely due to engineering choices made by people, not nature.
The only thing you could claim injustice for would be if there was no other mechanism for measuring blood oxygen other than something that was known to not work properly for people of color.
No one — myself including — is saying that physics is biased, or that this tool is inherently biased. The headline is misleading, it’s really talking about the interpretation of the number that’s biased, not the physics. The number is just a number.
The bias comes through the typical institutional use of this tool, as described in the article: the “normal” regions are based on “normal” for lightly pigmented people, so heavily pigmented people are by default not in the “normal” range. Do some doctors realize this? Of course they do. But as programmers we all know the power of defaults some doctors won’t realize this, or will forget, or will realize it but it will still affect them.
Other policies (like the Medicaid one described in the article) also ignore these differences.
It’s not the physics that’s biased. It’s the institutional and individual assumptions around the tool.
However yes, in my experience I never had enough difference in dark-skinned individuals to be clinically meaningful.
Threshold values are used to.make decisions, dark skin people do read higher (meaning decisions not informed by knowledge of the difference are likely to delay intervention for darker skinned people) and also have worse outcome with otherwise similar presentation for many of the conditions where pulse oximetry would be a factor in decision-making. It's quite possible that the outcome difference is in part because of the measurement difference, even if the likely impact in each individual case is minor.
The problem is that that '95' might really be a '90' - surely a drop from 98 to 90 is a cause for concern. If that information is being hidden, it needs to be fixed, regardless of other, more subjective fallback methods.
For reference I have two pulse oximeters at home and they routinely give me results that differ by 2-3%.
Seems like an issue we should fix, but I don't know what impact this would have in a clinical setting given that they use multiple criteria and the devices are known to be inaccurate.