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Pulse oximeters give biased results for people with darker skin

bostonreview.net

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Re: Pulse oximeters give biased results for people with darker skin

#61

Post by prvc »

jrajav wrote: post #26
treis wrote: post #13

This really isn't a big deal. Doctors know that these pulse ox meters aren't very accurate and use them accordingly. 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. In other words, they're looking for patients going from 98 to 75, not 98 to 95.

What's the point of casually dismissing this article's premise? Whether the conclusions are fully sound or not isn't the goal of this article, this is journalistic not academic. The goal is to raise awareness of a potential bias, and I think it achieves that (assuming the facts all check out). For one, according to the article the discrepancy was found to be up to 8 points in some cases, not 3. And it seems reasonabl…

>why don't we assume it does? Then the knowledge and awareness might spread a little bit more

If the assumption is incorrect, then it would be misinformation that we would be spreading.

Re: Pulse oximeters give biased results for people with darker skin

#62

Post by oneplane »

function_seven wrote: post #39
oneplane wrote: post #22

And darker coloured textiles are less visible on people with darker skin. Grass is green and bananas tend to be curved. I get that it is interesting to research optically measuring systems to 'search for bias' and I'm sure there are going to be biases in varying degrees, but that doesn't mean it's always for the same reason or with the same result. There are very real problems of course, take the example with the pho…

> Both of those are mostly examples of errors made during engineering (apply Hanlon's razor when in doubt - it's not always malice like people often assume), and might be preventable if there were more different samples and interactions available during development. When I see these types of examples brought up, I don't see malice being assumed. Rather, these are good illustrations of structural bias. "Structural" (o…

The issue is that we assume that there was a building somewhere, where a group of people sat down and designed and produced a device. (the soap dispenser) But we don't actually know that. If there is a single spot where this was done, and also where the testing was done, and there was an abundance of skin tones available, then this was caught. But that's a lot of ifs.

It could be that the device as designed and completed for manufacturing 15 years ago, the manufacturing was shifted around between 2 companies and the supply chain has 10 levels deep of participants that all did their own tests on their part in their own company in their own country on their own continent. And between that and the consumer it turned out there were 4 companies that just trade and don't actually look at, touch or use the product.

This is probably not what happened at Nikon, I'd guess that they have a few departments that may not work together as well as they could. Would be interesting to see how this actually came to be, I imagine there are many ways to create a (partially (bad)) product, and equally many ways to try to prevent that.

Re: Pulse oximeters give biased results for people with darker skin

#63

Post by dragonwriter »

treis wrote: post #13

This really isn't a big deal. Doctors know that these pulse ox meters aren't very accurate and use them accordingly. 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. In other words, they're looking for patients going from 98 to 75, not 98 to 95.

> Nobody's changing their plan because you have a pulse ox of 93 instead of 95.

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.

Re: Pulse oximeters give biased results for people with darker skin

#64

Post by krapp »

jeffreyrogers wrote: post #46
krapp wrote: post #43

Earlier quoted context omitted.

Seeking evidence of problematic issues is how society identifies and eventually addresses such issues. Do you believe society would benefit from ignoring evidence or pretending those issues didn't exist?

I agree that seeking evidence is how issues are addressed. The problem is that evidence is being sought in a particular way, which systematically biases which evidence is available for consideration. Edit: there is a further problem that because many interpretations of the same facts are possible if you go looking for certain things you will very likely find them. While someone with different initial beliefs will fin…

But you seem to be suggesting that we ignore skin color as a relevant factor, despite the data, out of a belief that any correlations drawn from that data must be distorted to further a political agenda.

The article presents what appears to be a plausible, evidence-based hypothesis as to why skin color in particular (not exclusive of other factors) might lead to inaccurate results for dark-skinned people. It then mentions studies done to either confirm or reject this hypothesis, and that the results seemed to confirm it. They link to a follow-up study done here[0].

You're only giving vague, general dismissals. If you believe the conclusions reached are in error, what evidence do you have that pulse oximeters are not affected by skin color?

[0]https://journals.lww.com/anesthesia-analgesia/fulltext/2007/...

Re: Pulse oximeters give biased results for people with darker skin

#65

Post by oneplane »

newacct583 wrote: post #59
oneplane wrote: post #22

And darker coloured textiles are less visible on people with darker skin. Grass is green and bananas tend to be curved. I get that it is interesting to research optically measuring systems to 'search for bias' and I'm sure there are going to be biases in varying degrees, but that doesn't mean it's always for the same reason or with the same result. There are very real problems of course, take the example with the pho…

> And darker coloured textiles are less visible on people with darker skin. Grass is green and bananas tend to be curved. The point isn't that people have different skin. It's not even that this one common device works better for some people than others. It's that the practice of medicine , having grown up around this cheap and effective device, turns out to be discriminatory in ways that we wouldn't naively expect.…

My point wasn't to suggest that skin tones are the only thing in the world that aren't considered by all the people during all product design phases. It was more that we know that this is a problem in our bubble of communication, we know it just as much that we know that grass tends to be green (or yellow-ish when it doesn't rain for a while and the sun is out).

It's more that having a higher quantity of a known problem doesn't make the problem go away, and neither does trying to find a single source or single instigator of a systemic problem. It's not a new problem either.

If we take skin color and replace it with finger length for devices that require you to grip it, or with distance between the eyes for things that you look through, we have the same issue. In that regard this is just another facet of ergonomics in design. Even if we were to test for a lot of things in a lot of places in the supply chain you still can't catch everything.

Re: Pulse oximeters give biased results for people with darker skin

#66

Post by rscho »

treis wrote: post #13

This really isn't a big deal. Doctors know that these pulse ox meters aren't very accurate and use them accordingly. 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. In other words, they're looking for patients going from 98 to 75, not 98 to 95.

We are looking for people to make 90+, 92+ if reasonably healthy. 75 is super low, and apart from exceptions is a _very_ concerning value. See the dissociation curve of hemoglobin/O2 to know why.

However yes, in my experience I never had enough difference in dark-skinned individuals to be clinically meaningful.

Re: Pulse oximeters give biased results for people with darker skin

#67

Post by function_seven »

oneplane wrote: post #48
vmception wrote: post #44

Earlier quoted context omitted.

The product just wouldn't have shipped with a product manager who also experienced it not working. Thats the point of inclusion. Although the soap dispenser example feels like one of those problems, it is just wear and tear of the sensor and they work properly when cleaned. In this case, pulseox failures, can have effects on when people are admitted for treatment.

It would probably not have shipped in that case, but the amount of product managers actually using their own products sadly isn't at the saturation you'd expect. Same with all the white labeling and supply chain and integrators in between; the disconnect between all of the stages and the contracts that can bind a bad product to be delivered and sold anyway can't be fixed on just one end of the process.

I'm going to challenge you on "...can't be fixed on just one end of the process"

Why not? That seems like the appropriate place to reject the inferior components arriving from that long and deep supply chain. You're creating a soap dispenser for sale in North America. It does not work on 15% of the population. That's a fail. You can't just throw your hands up and say, "Well, those photoreceptors were designed in Taiwan, and they didn't account for dark skin". If that's the case then you don't source those, or you request a different calibration profile, or you add a lens filter that compensate. You engineer the solution for your target market.

The same company using global components took the time to print logos in English and the user manual in English. They made sure the power circuitry matched North America's system. They set up a domestic phone number for support. Established payment systems to accept USD for their product.

They do all these things to sell better into a particular market, but they don't bother with the actual people who will be using it?

Don't get me wrong. You are accurately explaining the how of the failure. But that's exactly why the last step in the supply-chain exists. To make the actual finished product. That's where you catch deficiencies like this.

Re: Pulse oximeters give biased results for people with darker skin

#68

Post by jfengel »

oneplane wrote: post #50
jfengel wrote: post #47

Earlier quoted context omitted.

Each instance of it isn't necessarily malicious, but the way they all end up causing harm to the same people makes the system as a whole act as if it were malicious. Especially when combined with a proportion of people who are actively malicious, and when any attempts to address the systemic issue are dismissed. When it comes to us in particular, we can each truthfully say "it wasn't my fault and I didn't mean any ha…

The issue with all of this, is that it's not just one company with a group of all the parts that design, create, test and sell this stuff. Most of it was designed somewhere, built somewhere else, integrated yet somewhere else, and then simply bought out of a catalogue bulk, shipped to a warehouse and sold in smaller bulk to stores. The products and people that could have detected a problem are all over the world, and…

The chains do interfere with the problem, and one part of the solution is to have people at every single step who think of it as their problem. What I suspect happens in a case like this is that a white manufacturer asks a bunch of white engineers for a design, who sends it off to a Chinese manufacturing plant, to be shipped to a white buying agent in pharmacies. Nobody in the process is explicitly racist, but neither are there any black people in the process to say, "Hey, would this work on me?"

The problem comes when you say, "Hey, maybe there oughta be some black people involved in some of the processes", and people scream "reverse racism" and "affirmative action" and all the other buzzwords. They assert the harm to themselves, and they get listened to. But when black people say, "Well, I'm also being harmed, and in ways you're not seeing," the response is "well, that specific thing isn't my fault".

The solutions are systemic. As you say, it's a chain: for a black person to get hired into that position everything has to have gone right for them. They didn't get failed by bad schools and they didn't get dismissed by their professors and they didn't get filtered out by a resume screener who didn't like their name and they didn't lose a job to somebody who hires people they know -- which just doesn't happen to include black people.

So it's not easy to solve, and even the good solutions are slow. But one critical step is for each person to recognize that their local optimizations and local considerations contribute to the bigger problem, and think of ways that they can make things better rather than just say "not my problem".

Re: Pulse oximeters give biased results for people with darker skin

#69

Post by rscho »

vmception wrote: post #44
oneplane wrote: post #22

And darker coloured textiles are less visible on people with darker skin. Grass is green and bananas tend to be curved. I get that it is interesting to research optically measuring systems to 'search for bias' and I'm sure there are going to be biases in varying degrees, but that doesn't mean it's always for the same reason or with the same result. There are very real problems of course, take the example with the pho…

The product just wouldn't have shipped with a product manager who also experienced it not working. Thats the point of inclusion. Although the soap dispenser example feels like one of those problems, it is just wear and tear of the sensor and they work properly when cleaned. In this case, pulseox failures, can have effects on when people are admitted for treatment.

> The product just wouldn't have shipped with a product manager who also experienced it not working.

Yes sure, why don't we dispense with our most important and practical monitoring system because it has a racial bias? Pulsoxymetry saves lives every day. Many lives. Just ask old caregivers who were around before them.

Re: Pulse oximeters give biased results for people with darker skin

#70

Post by simion314 »

IndPhysiker wrote: post #51
simion314 wrote: post #12

Earlier quoted context omitted.

They look at a few studies too and asked around companies if they handled the issues mentioned in those studies, the most positive result was that some models from one company are now better)probably some of the others are not). IMO seems that the certifications for this devices, especially for the ones used by medical stuff to decide things need to be better tested. Other interesting point that I did not consider is…

Nonin created the first of these back in the '90s, so I pulled one of their spec sheets from 2016 ( https://www.nonin.com/wp-content/uploads/2018/09/NoninConnec... ) which explicitly mentions the pigmentation issue along with nail polish, poor circulation, and breathing issues. From that, this isn't exactly a new or unknown thing since commercial products have been working around this for some time. I wasn't able to…

> I wasn't able to find an industry standard for testing on these, so maybe the article should cite that as an opportunity to improve a product or add a new method?

It is a long article with many studies cited so I can't check all of those, IMO "the readings can be affected by skin tone" is not something that is sufficient for a medical device , what should a nurse or doctor do? There is no numeric value so what does that mean? is the device useless if you have dark sin or is it 2% wrong or as the article suggests the error is non linear and increases if you are suffering with low oxygen?

What I would do if I would sell this products is test with a few ranges of skin tones, and if needed have a switch on the device that you have to set for a certain level or if that is to expensive print instead of a number an interval and have the user trained to read that.

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