"Medical doctors prescribed drugs of which they know little, for the human body of which they know less, for dis-eases of which they know NOTHING at all" Virchow - We could accurately say, "Half of what physicians do is wrong," or "Less than 20 percent of what physicians do has solid research to support it."
Read the article below from Scientific American which supports this conclusion.
http://www.scientificamerican.com/article.cfm?id=demand-better-health-care-book