CHA Family Medicine Residency

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UberDx Chapter 4

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So now you know about Overdiagnosis Bias. The answer to Question 1 in Chapter 3 is “False”. In this scenario, screening does not diagnose more cancers, but the numerator and denominator are inflated because of all the false positives and “pseudodisease” screening creates. So it looks like the 10 year survival is better. Have you had to deal with this recently, as CHA has embarked on screening smokers for lung cancer? I certainly have. I really try to engage patients in shared decision-making about that and I basically try to talk them out of it. We know how to prevent lung cancer.

Ok, so take a look at this:

Cancer incidence

 

Can you think if some cancers that fit the A graph: we pick up more aggressive cancers by screening? How about the B graph: we seem to diagnose more, but there is no corresponding increase in number of people dying from the diagnosis? In B we are: 1. Picking up more benign cancers, 2. Simultaneously improving treatment while picking up more cancers, 3. Diagnosing more, maybe earlier, but having no effect on survival.

There aren’t too many good examples of “A”, at least for cancer. Alzheimer’s disease fits the graph pretty well, though. Cervical cancer is actually a good example, but the death rate begins to fall off after time, because we have good interventions.

There are a lot of examples that fit “B”. Prostate cancer. Thyroid cancer. Can you think of any others?

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Author: gemaxted

Associate Program Director Tufts University Family Medicine Residency at Cambridge Health Alliance

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