Blog | Monday, April 9, 2012

Your doctor is there for you, even when you aren't sick

A long-held precept of public health has been that prevention and early detection are "good things." We've always known that early detection (screening) is a tough nut to crack. Some conditions yield easily to our screening practices, some do not. Some diseases, when detected early, behave no better than when detected late. The course of hypertension, for example, is much more likely to be benign when detected early. Screening for lung cancer is much less satisfying. If X-rays or CT scans are used in a general population, they are not effective at discriminating sick people from well.

However, like most screening problems, the higher-risk the population, the more useful the testing. We still haven't found a good answer to lung cancer screening, but we do know that screening people already at higher risk is more likely to be helpful. The problem here, as with prostate cancer, is when we find a problem in otherwise healthy people, we may do more harm poking around than if we had just waited for the disease to pop up on its own. Many men with abnormal prostate tests go through painful and potentially dangerous testing that doesn't help extend their lives. But for other men it does. The trick is figuring out which men really do benefit from early detection.

An op-ed in the New York Times gives a distorted view of what we primary care physicians do, especially when it comes to screening. If he is trying to help us see the need for a revolution in medical care, he has failed and failed dangerously.

"The basic strategy behind early diagnosis is to encourage the well to get examined--to determine if they are not, in fact, sick. But is looking hard for things to be wrong a good way to promote health? The truth is, the fastest way to get heart disease, autism, glaucoma, diabetes, vascular problems, osteoporosis or cancer ... is to be screened for it. In other words, the problem is overdiagnosis and overtreatment."

Um, well, yeah but ... something is wrong with this statement. It is a statement that sort of re-states something called "lead-time bias," that is a disease seems more prevalent if we work hard to find all the people with the disease as early as possible. If you don't know about your diabetes, then as far as statistics are concerned, you don't have it and the number of diabetics is one fewer. Does this mean that "the problem is overdiagnosis and overtreatment?" In this case, the problem is over-generalization and over-simplification.

Early detection of many diseases is in fact a good thing, although the author argues that early detection "doesn't promote health but promotes disease." This is, in a word, insane.

He states that "there is a concern about too much detection and treatment of early diabetes," an incorrect, or at least simplistic reading of the evidence he cites. There is not yet a randomized controlled trial showing that population-wide screening and early treatment for diabetes is cost-effective and whether it reduces the well-known and devastating complications of the disease. It is known, however, that once it is detected, treatment significantly decreases the risk of heart attack, stroke, blindness, kidney failure, amputation ... you know, important stuff.

When populations are studied to assess the effects of high blood sugars, a continuum is found between people with normal sugars and those with higher and higher sugars. Diabetes begins its destruction early. Is stopping it earlier better? Is it ethical to do a randomized controlled trial to see, given the clinical plausibility of earliest intervention? Especially when that intervention is often exercise and dietary modification?

The author, Dr. Gilbert Welch, is selling a book called Overdiagnosis, but he makes a poor case for his thesis:

"For years now, people have been encouraged to look to medical care as the way to make them healthy. But that's your job--you can't contract that out. Doctors might be able to help, but so might an author of a good cookbook, a personal trainer, a cleric or a good friend. We would all be better off if the medical system got a little closer to its original mission of helping sick patients, and let the healthy be."

It may be "your job" to keep yourself healthy, but you aren't always good at it and neither am I when it comes to my own health. Studies show that being counseled by your doctor to quit smoking helps. Public health campaigns help too, but it's not the same as a face-to-face encounter. Reading a cookbook or listening to a cleric is not the same is a comprehensive visit to a doctor who can lay out what you need to do to stay healthy and who can help stop diseases before they claim you. This is both obvious and supported by the evidence.

Peter A. Lipson, ACP Member, is a practicing internist and teaching physician in Southeast Michigan. After graduating from Rush Medical College in Chicago, he completed his internal medicine residency at Northwestern Memorial Hospital. This post first appeared at his blog, White Coat Underground. The blog, which has been around in various forms since 2007, offers "musings on the intersection of science, medicine, and culture." His writing focuses on the difference between science-based medicine and "everything else," but also speaks to the day-to-day practice of medicine, fatherhood, and whatever else migrates from his head to his keyboard.