Friday, July 8, 2011

Noisy/Bad Information and Health Care Decisions

There was an interesting post on the Wall Street Journal's Health Blog about medical professionals and the use of social networks a few days ago. Much of it dealt with issues related to privacy (don't tweet about interesting cases in a manner that might identify patients, etc). However, I thought the most interesting part came at the end:

Montori says institutions and practitioners can raise awareness about conditions or available treatments, and also to counteract misinformation floating around online [using social networks]. “A lot of my colleagues say they don’t have time for distractions” like social media, he says. “But if folks who are really on the front lines of care cannot engage in this space, their thoughts, insights and experience will not be flowing through the network.”

And meantime, Montori says, “the thoughts of those who aren’t that busy, or who are paid to be in that space” will dominate. “Patients are receiving what they think is a signal but in fact it’s noise,” he says.


That last bit, about noisy signals, is an important one. It turns out that when health care professionals provide incorrect information, people learn from it in a way that is counterproductive. One of the most poignant illustrations of this comes from my friend and colleage Achyuta Adhvaryu, an economist who works on global health issues at Yale University. Adhvaryu was struck by how slowly people adopted new, highly effective anti-malarials in Tanzania after a brisk rate of uptake in the first year they were available. This is all the more weird given what we know about what malaria does to economic productivity.

Using an elegant and convincing set of theoretical and empirical techniques, he uncovers an interesting phenomenon: adoption rates are far lower in areas where the rate of misdiagnosis is higher. The story goes something like this: you have a fever, and go seek treatment. You get diagnosed with malaria and handed antimalarials. Now, if you actually have malaria, the treatment will make you feel better and you'll learn from that experience. If you don't have malaria, the treatment won't really help you and you'll lose belief in the new therapy. Adhvaryu's estimates suggests that this misdiagnosis effect is quite large and important.

We remain very interested in why people in developing countries don't adopt things like better vaccinations, malarial bednets, circumcision, etc. At a first glance, failure to adopt these cheap but potentially life-saving/enhancing interventions seem irrational. However, in a world where people respond to information, good or bad, accuracy in education and diagnosis can go a long way in encouraging socially optimal behaviors.

By the way, this is not just a developing country issue. When the medical journal Lancet published a startlingly dubious study linking measles vaccines to autism, a non-trivial number of people stopped vaccinating their kids. It all seems silly, but it emphasizes greatly the role of information, good or bad, in the decision making process.

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