When the information from medical tests can be harmful

We live in an age of technological medicine in which we have diagnostic testing available to us that would have seemed unbelievable 50 years ago. Much of that testing is beneficial. Some of the testing has a risk of physical harm and must be used only when justified by the situation. Much of it is very expensive and we need to avoid the cost of unnecessary use. Because of its many benefits we generally consider the information we obtain by doing medical testing to be a positive thing and sometimes assume it is always beneficial. We have a sense that we can never have too much information on which to make decisions about our health.

However, there are times when the information that we get from doing medical tests may be harmful. We need to realize that the potential harm from the information provided by the test is one of the risks of testing that we need to consider before doing a test. This was pointed out recently in a study done by Barbara Bernhardt et. al. about the experiences of women who received abnormal results of prenatal chromosomal microarray testing in an experimental study. The study was recently prepublished online by Genetics in Medicine and referenced in a recent article in U.S. News and World Report. The women agreed to the testing because it was being provided free to patients in a research study, but those who were found to have abnormal results found themselves in a position of having information that the fetus they were carrying had a chromosomal abnormality that was potentially serious, but how much their baby would be affected by that was not known. That left some of them wishing they had not had the testing done. The researchers labeled this situation “toxic knowledge” in which the information from the testing turned out to be seen by the women as more harmful than helpful.

This issue was also a part of the recent decision by the U.S. Preventive Services Task Force to recommend against screening for prostate cancer with PSA testing. Part of the decision was due to a lack of evidence of benefit from PSA testing, but it was significantly influenced by their understanding that the information that a screening test for cancer is abnormal leads to further testing and a confirmation of cancer leads to treatment even if there is no evidence that the treatment is helpful. Therefore the information that a screening test is abnormal can lead to more harm from further testing and the adverse effects of possibly unnecessary treatment than the questionable benefit of the testing.

While the medical tests that are available to us can provide very important information for our health, we need to remember that even the information we obtain from testing can be harmful and make wise decisions about the tests we do as well as the treatments we consider. We most commonly think of informed consent being needed when decisions are made about treatment that entails significant risk, but it can also be needed in the decision to do medical tests.

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Jon Holmlund, M.D.
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Jon Holmlund, M.D.

Absolutely. I think the core issue here is considering, in advance, what one will do with the information. In the prenatal testing example, one hopes that the consent form and consent process (the broader conversation between the subject and the researchers, prior to the subject’s providing consent) addressed not only that the results could or would be provided to the subject, but what, in broad brush, the implications of that might be. The benefits and, indeed, harms of knowing are important elements of informed consent that the researchers and the IRB reviewing their proposal and consent form must be sure… Read more »