Map of life expectancy at birth from Global Education Project.

Friday, August 17, 2018

More on overdiagnosis

Kale and Korenstein in BMJ give a good overview of the subject. There is a cognitive bias, not just in medicine but in people in general, I think, in favor of "doing something." We like to feel as though we're in control. We don't want to get cancer, or diabetes, or heart disease, so if we think there might be something we can do to improve our odds, we're likely to go for it.

Often, however, we can do more harm than good by our actions. But other cognitive biases make that hard to notice. Obviously, if we don't get cancer, we won't know that we wouldn't have gotten it anyway. We're likely to believe that the prostatectomy or whatever we went through saved our life because we don't like to think that all the suffering and damage we endured was unnecessary and that we made a mistake.

Another source of bias that promotes overdiagnosis is that doctors and drug companies and device manufacturers are paid for their services and goods. So naturally they tend to think that intervening is a good idea, and they'll advocate for it in general and do it for individual patients when they are parties to the decision.

K&K make a few recommendations to reduce overdiagnosis but the first issue they consider is the present topic of controversy, broadening of disease definitions. As I have tried patiently to explain, diseases are not generally entities "out there" in the world like apricots and camels that we just have to name. Rather, people decide that a test result above some threshold or a set of clinical observations qualifies you for a disease label. There are pressures to set those thresholds lower than cost-benefit analysis justifies. These thresholds are human constructions, decisions that people have made -- rather like the issue of brain death that we recently discussed. And those decisions can be changed.

And then, maybe, you don't have the disease after all. And nobody is lying to you. And you ought to be relieved.


Mark P said...

I remember a documentary some time ago that said that the manufacturers of drugs used to treat depression essentially created that diagnosis for the Japanese. Before the drug companies started pushing their treatments for depression, depression was very seldom diagnosed as such in Japan.

Anonymous said...

About every three years I get a high-speed electron beam tomographic full body scan without contrasting dye. This revolutionary machine uses about a tenth of the radiation that is normally used in these scans. My goal is early detection of problems that have few symptoms until they're almost untreatable such as pancreatic or liver cancer. I believe it's worth the risk.

I don't look to others to pay for my healthcare. I private pay for this service.

There's the view you're promoting of what's good for the masses and then there's *my* ass and what's good for me. I'm thankful that I currently have the option to direct my own healthcare and don't have my medical betters either financially or legally restricting my healthcare choices.

Don Quixote said...

Really unpleasant graphic.