Fishing expeditions: how our zeal to explain everything can harm children

January 17, 2017  |  General

A fairly recent article in the journal Pediatrics is both intriguing and sobering. It is intriguing because it lays bare something we don’t talk much about or teach our students about; it is sobering because it describes the potential harm that can come from it, harm I have personally witnessed. The issue is overdiagnosis, and it’s related to our relentless quest to explain everything.

Overdiagnosis is the term the authors use to describe a situation in which a true abnormality is discovered, but detection of that abnormality does not benefit the patient. It is not the same as misdiagnosis, meaning the diagnosis is inaccurate. It is also distinct from overtreatment or overuse, in which excessive treatment is given to patients for both correct and incorrect diagnoses. Overdiagnosis means finding something which, although abnormal, doesn’t help the patient in any way.

Some of the most controversial and compelling examples of overdiagnosis come from cancer research. Two of the most common cancers, prostate cancer for men and breast cancer for women, run smack into the issue. It is certainly generally true early diagnosis and treatment of cancer is better than late diagnosis and treatment . . . usually, not always. A problem can arise when we use screening tests for early cancer as a mandate to treat them aggressively when we find them. The PSA (prostate-specific antigen) blood test was developed when researchers noticed it went up in men with prostate cancer. From that observation it was a short but significant leap to use the test in men who were not known to have cancer to screen for its presence. The problem is at least two-fold. There is overlap between cancer and normal, and many small prostate cancers do not progress quickly. Since the treatment for prostate cancer is seriously invasive and has several bad side effects, the therapy may be worse than the disease, especially in older men. You can read more about the PSA controversy here. There are similar questions about screening for breast cancer; you can read a nice summary here. The controversy has caused fierce debates.

Children don’t get cancer very often, but there are plenty of examples of overdiagnosis causing mischief with them, too. The linked article above describes several common ones. A usual scenario is getting a test that, even if abnormal, will not lead to any meaningful effect on the child’s health. Additionally, an abnormal test then typically leads to getting other tests, which can lead to other tests, and so on down the rabbit hole. I have seen that many times. As the authors state:

Medical tests are more accessible, rapid, and frequently consumed than ever before. Discussions between patients [or their parents] and providers tend to focus on the potential benefits of testing, with less regard for the potential harms. Yet a single test can give rise to a cascade of events, many of which have the potential to harm.

This is kind of a new frontier in medicine, and the issue grows larger as the huge number of diagnostic tests we have mushrooms every year. For a parent, a good rule of thumb is to ask the doctor not just what the benefits of a proposed test are, but also the risks. Importantly, ask what the doctor will actually do with the result. We are prone to think more information is always a good thing, but that clearly is not the case. And never, ever get a test just because you (or your doctor) are merely curious.

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