WASHINGTON -- A new study suggests that doctors are gravitating to states with limits on malpractice awards.

Dartmouth researchers studied growth in the number of physicians compared to residents from 1970 to 2000. They found a slightly higher growth rate -- 86 percent -- in states that had enacted caps in the 1970s.

By the 1980s, that growth rate had jumped to 102 percent in states with award caps, according to the study, which is published on the Web site of the journal Health Affairs.

The researchers said they factored in various items that might account for the increase in physicians, such as income and unemployment rate.

A spokesman for the advocacy group Public Citizen said many of the states with malpractice limits are conservative states in the South -- a region of rapid population growth.

"Doctors are like anybody else; they go where the business is," he said.

But a separate study published in Wednesday's issue of the Journal of the American Medical Association found that caps on malpractice damages and other changes in liability law appear to have less effect on the nation's supply of doctors than supporters of tort reform contend.

But the study, conducted by Stanford University researchers, conceded that states that enacted malpractice reforms had an increase in their overall supply of physicians.

Another survey in Wednesday's JAMA found that the fear of getting sued has led an alarming number of doctors to practice "defensive medicine." They're taking steps such as ordering unnecessary tests and avoiding risky procedures.

Researchers say the practice has been around for decades and is no secret to many patients. But the survey suggests it's surprisingly common. Of nearly 830 Pennsylvania doctors surveyed in 2003, 93 percent said they sometimes or often practiced "defensive medicine" because of malpractice concerns.

Both studies appearing in JAMA were funded by the Pew Charitable Trusts.

Yet another study suggests that the high cost of malpractice insurance for obstetrics and gynecology is limiting not only the number of doctors choosing to enter the field, but also where they choose to practice.

In the study, published in the June issue of the journal Obstetrics & Gynecology, University of Michigan researchers said some of the potential problem areas include states with the highest malpractice premiums. Populous cities in those states are at highest risk of losing doctors, the researchers said.

Malpractice insurance premiums vary widely from state to state, according to the study. Florida is the highest-premium state, with an average 2004 premium of more than $195,000, followed by Nevada, Michigan, the District of Columbia, Ohio, Massachusetts, West Virginia, Connecticut, Illinois and New York.

The 10 lowest-premium states are Oklahoma, at about $17,000 on average, and Nebraska, South Dakota, Minnesota, Indiana, Idaho, North Dakota, Wisconsin, Arkansas and South Carolina, the study says.

"Something has to be done about the skyrocketing cost of malpractice premiums in our field," said Scott Ransom, the paper's senior author. "We are going to lose some of the best and brightest young doctors who otherwise might enter this field, and we are going to face shortages in many areas of the country if something isn't done."

Additional Resources:

• Health Affairs: The Growth Of Physician Medical Malpractice Payments
• JAMA: Defensive medicine study
• JAMA: Impact of Malpractice Reforms on the Supply of Physician Services
• Obstetrics & Gynecology: Obstetrician–Gynecologist Supply