I'm not sure if you can read this -- I have a cookie that gives me access, but the URL doesn't include the proxy server and it appears to be accessible. Let me know. Anyway, it's a discussion in NEJM of the U.S. Preventive Services Task Force. The USPSTF is a panel of clinical experts convened by the Agency for Healthcare Research and Quality, AHRQ, which is usually pronounced like ark. It draws on available research to evaluate screening tests and preventive interventions. An A or B grade means they recommend it. A C grade means it might be worthwhile for some people, but you should discuss it with your doctor and make your own decision.
Under current law, anything with an A or B grade has to be covered by insurance, but a recent court decision, based on a fairly arcane technicality about the legal authority of the Task Force, has that in limbo. Basically, conservative judges don't like any form of regulation and they are using ridiculous constitutional theories to try to eliminate the powers of the federal government. That's kind of disturbing, but it's not what I want to focus on right now.
The Task Force members are all generalist clinicians, by design. The main reason has to do with screening tests. If you've been here recently you've come across the Bayes theorem. Without rehashing all that the essential point is that even a very accurate screening test will produce false positives, maybe even most of the time, depending on the underlying rate in the population of whatever you are screening for. False positives can result in a lot of harm. That has to be weighed against whatever good results from early detection. Both of those considerations are usually difficult to measure and weigh accurately, and in fact have a lot of subjective components.
Specialists in a relevant field have both a financial incentive and a psychological bias to favor screening tests. For example, oncologists like screening tests for cancer because they bring in more business, and because oncologists tend to have an elevated conception of their own importance and powers. The paradigmatic examples are screening for breast cancer and prostate cancer, which is handy because it means equal opportunity for benefit and harm for either sex. In both cases, many of the lesions detected by screening would, if left alone, never go on to cause any problems. The problem is you can't tell for sure, and if you say the word "cancer" to a patient, they'll probably get scared and want to so something about it, and your oncologists is very likely to agree. But there are possible, even likely harms to surgery and chemotherapy.
The case for breast cancer screening -- mammography -- is better than the case for prostate cancer screening, at least in women age 50 and older and especially between ages 60 and 70. It's even stronger for women with known risk factors, such as family history. But there's still controversy about it. The case for prostate cancer screening is really not good for anybody, but right now it has a recommendation to discuss it with your physician and make your own decision. The main point I want to make is that it's natural just to assume that early detection has to be good and what's the harm in checking? But it's actually not that simple at all. Too much medicine can be just as bad as too little.
Note: I got a flood of disinformation in comments on my last post about the Covid-19 vaccine. No, the incidence of cardiac arrest in young athletes has not increased. That's a pure fabrication. I think I will discuss the issue, since obviously it's on people's minds.
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