Someone with a PhD in microbiology explained to me (a layman) why what Theranos was claiming to do was impossible. She said you cannot test only a single drop of blood for certain things because what you are looking for literally may not be there. You need a full vial of blood to have a reliable chance of finding many things.
1. Is this simple but clear explanation basically correct?
2. If so, how could Theranos hoodwink investors for so long when possibly *millions* of well-educated people around the world knew that what they were claiming to do made no sense?
In: Biology
>Is this simple but clear explanation basically correct?
Yes, but that was not the only problem.
This is a political year, so I will use a political metaphor. Imagine if someone told you that they had developed an “accurate” presidential election poll which sampled only 10 Americans, selected at random. Even with a rudimentary understanding of statistics you’d recognize that this is ridiculous – the error margins for such a small sample would be so large they render the result useless. Further, since the US is a large and diverse country, a sample of 10 might not include any of its subpopulations. You might oversample some states and – at best – you’d completely miss at least 40 others.
Laypeople often think that blood is a homogenous fluid, and its constituent molecules and components are evenly distributed throughout the body. While this might be true of some things (like glucose – a small molecule which is highly soluble in water) it is not true of everything else. So you need a decent volume to get a representative sample.
That was just one of Theranos’ problems though. More concerning was their claim that a battery of home tests would help the patient by giving them more information about their health. This isn’t really true.
Diagnostics is like a game of 20 questions, where individual questions are most helpful in the context of all the questions that came before. (This is Bayesian reasoning, which is also something that laypeople tend not to fully understand.) Asking the wrong question at the wrong time, or considering the questions in isolation, can send you down the wrong road.
This, by the way, is why your doctor doesn’t just order “all the tests” and follow up on the abnormal results. (Patients will occasionally request this, and that’s basically what Theranos was offering.) In medicine any specific blood test (or, for that matter, imaging) should really only be performed in the appropriate clinical context – after a full history, and physical exam, and with a specific question to be answered – because only then is an abnormal result informative. An “high” or “low” number on a blood test might be completely unremarkable, depending on the specific situation. Chasing an isolated “abnormal” test result can lead to misdiagnosis, unnecessary treatment, and potential patient harm. As I recall, there were a few examples of this in the Theranos cohort.
>If so, how could Theranos hoodwink investors for so long when possibly *millions* of well-educated people around the world knew that what they were claiming to do made no sense?
Because well-educated people aren’t experts on every topic and are just as susceptible to clever marketing, unfortunately. People who know how blood is composed would be immediately skeptical of the *feasibility* of Theranos’ product. People who understand diagnostics and Bayesian reasoning would be immediately skeptical of the *utility* of the product. Theranos’ investors understood neither.
Wh.. where are the Thanos jokes?
I am not smart enough to make them myself, see.
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