In 2003 researchers surveyed Pennsylvania doctors in six specialties with a high risk of malpractice lawsuits, among them emergency medicine, general surgery and obstetrics. Of the 824 who answered, 93% said they practiced defensive medicine. They ordered extra tests, sent patients to other specialists without need, and avoided high-risk patients. The study appeared in the Journal of the American Medical Association in 2005.
In 2010 a study in Health Affairs estimated the cost of defensive medicine in the United States at $45.6 billion a year.