Health Affairs, a health policy journal, published the two studies by researchers at Dartmouth College and the Agency for Healthcare Research and Quality.

Nevada health professionals say malpractice payments were a direct contributor to rising premiums. They also say they are happy to hear that physicians are lured to states with malpractice award caps since Nevada set $350,000 caps per case on pain and suffering jury awards in a voter ballot initiative passed in November. (The bill also limited attorneys' fees, established periodic payments for doctors, and limited physicians' liability to the portion they were responsible for.)

In 2004, the American Medical Association listed Nevada as one of 20 states in a medical malpractice crisis because the threat of malpractice litigation was great and many doctors left the state to practice.

The American Medical Association and physicians have long said that malpractice premiums are on the rise because of massive jury awards, but Amitabh Chandra, an associate professor of economics at Dartmouth and a senior research associate for Dartmouth's Medical School, said that is not the case.

Chandra and two co-authors reviewed publicly available data from the National Practitioner Data Bank, which is where physicians are required under federal law to report malpractice payments within 30 days or incur fines.

The study reported that malpractice payments -- including jury awards and settlements -- increased an average of 4 percent per year from 1991 to 2003, which is consistent with the increase in health care costs. The study was based on 184,506 malpractice payments made between January 1991 and December 2003 in the 50 states and excluded payments made by hospitals. Doctors with medical degrees made about 94 percent of those payments and the remainder were by doctors with osteopathic degrees.

While malpractice payments increased in line with medical costs, malpractice premiums rose an average of between 20 percent and 25 percent in 2002 for internists, general surgeons and obstetricians. Specialists in some states saw one-year increases of 75 percent, the study said.

Those premiums have led doctors and President Bush to call for a national $250,000 limit on noneconomic damages, or pain and suffering awards.

Dr. Rudy Mathei, an ophthalmologist and leader of Nevada's malpractice reform initiative, said the study is not an accurate depiction of what happened in Nevada.

"That's not true in Nevada," he said of the study. "The issue occurred in 2001 in which the awards for that year were $21 million."

In the prior five years, Nevada's malpractice payouts totaled $22 million, he said, adding that the frequency of payouts and significance of them increased Nevada premiums. Nevada doctors paid out $355 million from 1991 to 2000 that resulted from 1,971 cases during that period.

"Nevada data have shown that the premiums for physicians in certain areas of health care have tripled and quadrupled and were keeping pace with frequency and malpractice payouts," Manthei said. Those most affected included doctors specializing in obstetrics, cardiac surgery, emergency medicine, orthopedics and neurosurgery.

For example, an obstetrician with no malpractice claims could have premiums of between $90,000 and $150,000, which "precluded a lot of doctors that wanted to come to Nevada," he said.

"The bottom line is that those large awards add to the system and once you start that cascade you can't stop it," he said, adding that is why doctors pushed for malpractice caps.

The study said that 96 percent of malpractice cases are settled outside of court and that news reports about large jury awards can be misleading because the final amounts are often significantly reduced.

It also found that the largest payments grew less than the overall number of payments and cases involving operation of the wrong body part or foreign objects being left inside the body are involved in less than 2 percent of all malpractice payments.

"The large jury awards that attract so much public attention actually are rare events and comprise a very small portion of all malpractice payments," Chandra said in a statement. "They're certainly not key drivers of malpractice insurance increases."

He contends that the increase in malpractice premiums is attributed to a combination of state regulation of malpractice insurers, changes in their investment income and local competition among insurers.

Nevada has six malpractice insurance carriers that actively write policies for physicians. A few other insurers write a limited number through alternative plans and purchasing groups.

After the malpractice ballot initiative passed in November, some insurance carriers said they would reduce malpractice premiums in Nevada after ensuring that the caps would not be overturned by the courts.

The Nevada Division of Insurance said Nevada Mutual Insurance Co. was approved for a net 2 percent reduction in its premiums rates since the ballot initiative, while the Medical Liability Association of Nevada has filed for a nearly 15 percent rate increase that is pending with the division. Those two carriers represent 67 percent of the 3,315 doctors insured with the major malpractice carriers.

Chip Wallace, a director with Nevada Mutual Insurance Co., said his company intended to raise premiums because the cost of doing business was rising from the malpractice payouts but applied for a rate reduction after the ballot initiative passed.

"We're sitting here with crossed fingers waiting to see what happens with any Supreme Court challenges," he said.

Wallace questioned the validity of the Dartmouth study, saying that malpractice payouts increased the cost of operating.

"The cost of doing business is obviously directly attributed to the cost of goods," he said.

The second Health Affairs study, conducted by William Encinosa and Fred Hellinger of the Agency for Healthcare Research and Quality, said there is a link between high malpractice jury awards and where physicians practice.

The researchers found that the median number of physicians per 100,000 people grew 83 percent from 1970 to 2000 in states without a malpractice cap, while physician growth was 102 percent in states that established malpractice payment caps in the 1980s.

Malpractice caps were linked with five additional physicians per 100,000 people within three years of establishing the caps. States with caps of $250,000 experienced a greater increase in surgeons and obstetricians, which are at higher risk of malpractice claims.

From 1975 to 2000, OB/GYNs per 100,000 females ages 15 to 44 increased 40 percent in states that had a malpractice cap in the 1980s, compared with an 8 percent increase in states without a cap, the study said. There are 27 states including Nevada that now have caps on damages.

Michelle Swafford covers health care and small business for In Business Las Vegas and its sister publication, the Las Vegas Sun. She can be reached by e-mail at swafford@lasvegassun.com or at (702) 259-2326.