Repeal of Pennsylvania's motorcycle helmet law has led to a big increase in serious head injuries, according to a University of Pittsburgh study made public yesterday.

In September 2003, Pennsylvania largely repealed its law requiring motorcycle riders to wear helmets. Under current law, the only riders required to wear them are those under 21, and those who have less than two years of experience and who have not taken a safety course.

Researchers from several of Pitt's Schools of Health Sciences examined discharge data from all acute care hospitals in the state for the two years preceding and the two years following repeal. They found a 32 percent increase in head injury deaths, and a 42 percent increase in head injury hospitalizations. The non-head-injury death rate did not change.

There were 1.3 head injury deaths per 10,000 motorcycle registrations in 2001 and 1.9 in 2002. In 2004 and 2005, those jumped to 2.8 and 3.0, respectively.

The number of head-injured, hospitalized motorcyclists requiring further care at facilities specializing in rehabilitation and long-term care increased 87 percent after repeal of the helmet law, the researchers found. Total acute care hospital charges stemming from motorcycle-related head injuries rose 132 percent.

In dollars, for 2001 and 2002 together, acute care hospital charges totaled $53.5 million. They rose to $124.2 million for the years 2004 and 2005.

Helmet use by motorcycle riders involved in reported crashes declined from 82 percent in the two years before repeal of the law to 58 percent afterward, the Pitt researchers said.

In 2006, the state Legislative Budget and Finance Committee reported a 33 percent increase in trauma center admission rates for motorcycle-related head injuries for the years 2004-2005 from the years 2001-2002, but only an 11 percent increase in motorcycle-related deaths. That study didn't distinguish between head injury deaths and all motorcycle injury deaths. The Pitt study did.

"Our findings strengthen the argument for more comprehensive helmet laws that help protect riders and lower the cost of health care," said study co-author Hank Weiss, an associate professor in Pitt's Department of Neurological Surgery in the Center for Injury Research and Control.

Motorcycle helmet laws have weakened nationwide since 1975, when the federal government stopped withholding highway money from states that did not have them. Only 20 states currently require all motorcycle riders to wear helmets.

"You can make a study say almost anything you want," said Lynn Wesley, legislative coordinator for ABATE (Alliance of Bikers Aimed Toward Education) of Pennsylvania, a group that lobbied for the 2003 relaxation of the helmet law. "Medical mistakes are the third leading cause of deaths. Maybe the doctors should clean their own closet before they throw stones at others."

The best way to reduce motorcycle accidents is to focus on avoiding collisions, not on surviving them, said Steve Zurl, public relations director for ABATE of Pennsylvania. Louisiana recently passed a stricter helmet law, he said, but fatalities went up.

"A very high percentage of fatalities involve untrained, unlicensed riders," he said.

Another reason there are more fatalities in Pennsylvania, Mr. Zurl said, is that motorcyclists from Maryland, New Jersey and New York, which have strict helmet laws, come to Pennsylvania so they can ride without helmets.

"They're attracted by freedom of choice," he said.

The study, which was led by Dr. Kristen Mertz, an assistant professor in the Department of Epidemiology in the Graduate School of Public Health, will be published in the August issue of the American Journal of Public Health.