Amazingly enough, researchers have yet to measure a significant aggregate effect of medicine (doctors, etc.) on health.
Sure there are lots of clinical studies purporting to show the benefits of various treatments. But clinical trials tend to study best practice on patients mostly likely to benefit. Negative results tend not to be published, and the vast majority of medical practice has yet to be studied with clinical trials.
The studies that have looked at the aggregate health effect of medicine as typically practiced, averaging over all the things doctors do, have no found a significant effect. Two decades ago ~$50 million was spent on a randomized trial among 5000 people over 2-3 years, some of which got 1/3 more medical care than the rest. The only differences found were corrected vision via glasses, more filled teeth cavities, and lowered blood pressure among the poor (which may be a placebo effect). A recent analysis of 5 million Medicare patients, using regional spending variations of a factor of two (controlling for lots of stuff), found that any mortality benefit of spending in the last six months of life is less than a one part in a thousand.
Is this all from anal statisticians imposing too high a standard of evidence? Consider that by these same standards we *have* seen significant robust effects of age, exercise, fat, smoking, and social status on health. (Exercise and social status reduce mortality by roughly a factor of three each.)
How could medicine not be healthy? Surgery clearly has negative effects on the body, drugs upset evolved balances, and hospitals are clearly great places to spread contagious diseases. It is widely accepted that centuries ago doctors did many harmful things like bleeding folks along with a few useful things they did, and that the net effect may not have been positive. The same may be true today.
Of course most of this data is about the "second half" of the money we spend on medical care. Maybe we get more health value for the first half of spending. Or maybe not.
The apparent low health value of medical care is all the more striking given that we spend 14% of GDP on it in the U.S. And it must surely give pause to those who hope that medicine will soon give us dramatically expanded life spans.
Robin Hanson
hanson@econ.berkeley.edu http://hanson.berkeley.edu/ RWJF Health Policy Scholar FAX: 510-643-8614140 Warren Hall, UC Berkeley, CA 94720-7360 510-643-1884 after 8/99: Assist. Prof. Economics, George Mason Univ.