Wednesday, October 12, 2011

Health Confusion -- or Consistency?

Two contrasting and interesting issues in health care arose in the last week.

First, we have the US Preventive Services Task Force recommending that men not get routine PSA tests to screen for prostate cancer. See here for one of the thousands of articles reporting the recommendation. Without going into too much detail, I would summarize the recommendation as being based on the test being relatively uninformative, especially in regard to distinguishing between cancers that will progress dangerously versus those that will remain contained. Further tests beyond the PSA -- biopsy -- run risks themselves, and are also unable to finely distinguish cancer types.

The recommendation runs afoul of a core principle in information economics, which is that more information is at worst valueless (and the recommendation is not based on cost of the test).

There are subsidiary assumptions that can make a test be of negative value, but I would like to see them laid out (for example, reliance on an expert for further actions, with that expert biased by an agency problem).

I continue to be bothered by this idea of not having a test. As one of my colleagues put it: Suppose a doctor did a PSA test on you and emailed you the results. You are saying that you would pay for a spam filter to keep from knowing the result? I think it is possible to set up an optimal decision rule based on test results, which given a noisy test, will often lead to no action. But in some extreme cases, it will lead to a biopsy, identification of a severe grade tumor, and surgery that is valuable. The key is to not taking action for many outcomes.

Second, we have a bill in California, passed by the CA legislature, that would REQUIRE doctors to inform women that their mammogram revealed they have "dense" breast tissue. Now I am really venturing outside of my area of even limited expertise, but the idea here seems to be that dense breast tissue can prevent a mammogram from revealing small tumors. So if women have dense breast tissue, their mammogram might not be as accurate, and they might want to have a different screening test.

Governor Jerry Brown vetoed this bill by the way.

So on the one hand, we have a recommendation that men NOT be given a test for cancer, partly on the grounds that it would lead to more testing, while on the other hand we have a law saying that women MUST be given information that will cause those women to have more tests.

While there might be some inconsistency here, the consistent theme is that consumer/patients are not good at making health care decisions.

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