Monday, July 19, 2010
1. The test is accurate.
2. The result has meaningful predictive value.
3. There is something meaningful to be done if the test is positive.
The amazing thing is that so many extremely common medical treatments, particularly expensive and dangerous treatments, have tests that simply fail these very simple rules. I fully expected that all kinds of alternative medicine like homeopathy, naturopathy, aromatherapy, acupuncture and others would completely fail to measure up but I didn't anticipate how incredibly weak the reasons for more mainstream treatments like angioplasty, stents, prostate exams and mammography would be. It seems to be largely true that doctors want to treat patients who come to them with problems even when the problems are insoluble and that the desire to do *something* overrules the desire to do the right thing.
The best two examples in my opinion are prostate cancer and angioplasties done for heart concerns. Even if you can easily figure out if someone has prostate cancer you are faced with the problem that removing the prostate has an unimpressive rate of preventing death by prostate cancer and it causes huge numbers of problems including impotence and urinary leakage in many of those who undergo surgery. The other problem is that prostate cancer usuall takes a long time to kill people so many older patients who undergo treatment have no reason to think they will live long enough for prostate cancer to kill them. Even trying to prevent heart attack by angioplasty is noted to cause cognitive problems (due to breaking up plaques that then cause mini strokes) and is wretched to useless at saving lives since so many people die during the operation itself.
I have real first hand experience with excessive medical testing from my work. In a job I had last year I was working for a private clinic that got CEOs, VPs and the super rich to come in for massive batteries of tests each year. They were tested far more often than makes any sense even if you assume that the treatments would be helpful... and in many cases it seems that isn't true. I figured at the time that if rich people want to blow money being pandered to and tested excessively it wasn't any problem of mine since otherwise they would be buying status symbols with that cash but the fact that this was supported by doctors and was only unavailable to the public due to funding constraints is a sad state of affairs.
Just because a doctor can cut you open and make an effort to fix things inside you is no guarantee that doing so is a good idea. Testing itself costs the patient in time, stress and life disruption and invasive surgery is much worse. Although we might wish that modern medicine could solve all our health problems that is not the way things are. We would all be much better off if our doctors could tell us that there is nothing they can do but wait and see and if we were willing to accept that as the best science has to offer.