Saturday, April 4, 2015

Why not test your blood every quarter?

Lenny just pointed me to a little internet kerfuffle emerging because of Mark Cuban’s twittering about saying it would be a good thing to run blood tests all the time. Here's what Cuban said:

Essentially, his point is that by using the much larger and more well-controlled dataset that you could get from regular blood testing, you would be able to get a lot more information about your health and thus perhaps be able to earlier action on emerging health issues. Sounds pretty reasonable to me. So I was surprised to see such a strong backlash from the medical community. The counter-argument seems to have a couple of main points:
  1. Mark Cuban is a loudmouth who somehow made billions of dollars and now talks about stuff he doesn’t know anything about.
  2. Just as whole body scans can lead to tons of unnecessary interventions for abnormalities that are ultimately benign, regular blood testing would lead to tons of additional tests and treatments that would be injurious to people.
  3. Performing blood tests on everyone is prohibitively expensive, so we’d end up with “elite” patients and non-elite patients.
I have to say that I find these counterarguments to be essentially anti-scientific. On the face of it, of course Cuban is right. I’ve always been struck by how unscientific medical measurements are. If we wanted to measure something in the lab, we would never be as haphazard and uncontrolled as people are in the clinic. There are of course good reasons why it’s more difficult to do in the clinic, but just because something is hard does not mean that it is fundamentally bad or useless.

I think this feeds into the most interesting aspect of the argument, namely whether it would lead to a huge increase in false positives and thus unnecessary treatment. Well, first off, doing a single measurement is hardly a good way to avoid false positives and negatives. Secondly, yes, in our current medical system, you might end up with more unnecessary treatment–with many noting that getting into the system is the surest way to end up less healthy. That is more of an indictment of the medical system than of Cuban’s suggestion. Sure, it would require a lot more research to fully understand what to do with this data. But without the data, that research cannot happen. And having more information is practically by definition a better way to make decisions than less information, end of story. To argue otherwise sounds a lot like sticking your head in the sand. I'm also not so sure that doctors wouldn't be able to make wise judgements based on even n=1 data without extensive background work. Take a look at Mike Snyder's Narcissome paper (little Nature feature as well). He was able to see the early onset of Type II diabetes and make changes to stave off its effects. Of course, he had a big team of talented people combing over his data. But with time and computational power, I think everyone would have access to the interpretation. What's sad is for people to not have the data.

Leading to another interesting point from the medical research standpoint. If it were really rich people making up the primary dataset, I don’t think that’s a bad thing. Medicine has a pretty long history of doing testing primarily on non-elite patients, after all.


  1. Being in the hospital setting every day made my knee-jerk reaction the doctor-y one. I appreciate the contrarian view and it made me think twice about Cuban's claim.

    I think the valid criticism is #2 in your list. And yes, it *is* partly an indictment of how medicine is practiced. The elements that play into an errant sequence of events leading to unneeded treatment are essentially two-fold (also poetically named Ulysses syndrome!
    1. Fear of malpractice / defensive medicine. It's mindboggling how many people come in with low back pain (the run-of-the-mill, can't do anything about, old-age kind) who get troponin checks, a test for an acute heart attack. This is simply because no physician wants to miss an unusual presentation of a heart attack. We could indict the lawyers for defensive medicine... but I think the underlying issue is an immutable cultural belief rooted in American exceptionalism that even if a test/treatment will fail in 99.9% of cases, we should do it anyway.
    2. Lack of knowledge. If we had all patients' data in the world in a database, tracked their entire lifetime, we'd know a lot more than we know now. Maybe this is an argument siding with Cuban for more extensive/frequent testing! On the other hand, the combinatorics of normal/abnormal lab tests + presentation + variation in each patients history + exposures + medicines + genetics are so large, I think even if we had all patient data, there's not enough brainpower in the world to deduce every possible scenario and determine its significance.

    Instead, medicine is predicated and (should be) practiced on priors. Given the patient has no chest pain and is in fact complaining of left elbow pain, the chance they're having a heart attack is low--and no test is required. If we want to argue that quarterly blood draws are able to move up detection of type II diabetes, and that such detection improves patients' diet, and ultimately decreases adverse health outcomes, then someone should do a study to prove it!

  2. Agree! Checkout my similar blog post, with more of a focus on tech importance for personalized medicine to work..

  3. Regular Blood testing is good for everyone. It will help you to get information about your health and if there is health issue then you can treat it immediately.
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