Washington Post has a medical malpractice article: What Crisis? GAO: Malpractice Premium Spikes Don't Force Out Docs . The last two paragraphs state:

"Nationally, studies have found that doctors and hospitals win about 70 percent of cases that make it to a courtroom. Multimillion-dollar awards by juries are often bigger than the amount actually paid by an insurance company or doctor; these awards can be reduced by a judge, overturned on appeal or, more commonly, are the subject of negotiations between lawyers for both sides that dramatically reduce the amount a victim receives.

"What's often lost in this discussion is that there is much more malpractice than there are malpractice suits," Napoli noted. A 1991 study by Harvard University researchers, still regarded as the most influential of its kind, found that acts of medical negligence are eight to 10 times more common than malpractice lawsuits."