Most doctors in specialties prone to malpractice lawsuits order unnecessary tests and practice other forms of defensive medicine in seeking to avoid litigation, a survey in the Journal of the American Medical Association found.

Responses from 824 doctors in Pennsylvania, most of them surgeons, emergency-room physicians or obstetricians and gynecologists, showed that 93 percent provided excessive treatment or avoided patients and procedures they thought could lead to lawsuits. The survey, funded by the Pew Charitable Trusts, was sent via mail to 1,888 Pennsylvania doctors in May 2003.

The rate of doctors practicing defensive medicine was higher than in previous studies of broader groups or physicians who have fewer legal risks, said researchers led by David Studdert, associate professor at Harvard School of Public Health in Boston. The precautions create difficulties in finding doctors for some cases and exposes patients to extra medication, side effects and needless and painful procedures such as biopsies, the report said.

"In a state that is very heavily involved in the current malpractice crisis, the practice of defensive medicine was extremely high among physicians who paid the most for liability insurance and were at the highest risk of being sued," Studdert said. "That has implications for the way physicians practice medicine, and it's not very good for patients."

The results probably reflect the situation in states similar to Pennsylvania, where malpractice insurance for a general surgeon in Philadelphia more than doubled to $72,518 in 2003 from $33,684 three years earlier, the researchers said.

The cost of defensive medicine tops $100 billion annually, according to a widely cited 1996 study on the topic by Daniel Kessler, a professor at Stanford University in California, with his colleague at the time, Mark McClellan, who now heads the U.S. Medicare and Medicaid health insurance programs.

Malpractice costs topped $24 billion in 2002, a Congressional Budget Office report found. President Bush is asking Congress to pass legislation capping non-economic damages in malpractice cases.

New rules governing insurance coverage and costs, not caps on damages or other medical malpractice proposals, are needed, said Todd Smith, president of the Association of Trial Lawyers of America, in a statement.

"If our goal is to make health care safer and more affordable, then we need insurance reform to help doctors with their premiums, and patient safety reform to help reduce the 100,000 Americans killed each year by medical errors and negligence," Smith said.