A new study has identified blood clots in the lungs as yet another health problem that disproportionately affects blacks in Pennsylvania.

The study, led by researchers at the VA Pittsburgh Healthcare System, concluded that blacks with the clots, known as pulmonary embolisms, were 30 percent more likely to die than whites once the data were adjusted for other health factors that could affect mortality risk.

The findings, released early online, are being published in the December issue of the American Journal of Public Health.

Reasons for the higher death rates among blacks are unclear, but differences in medical treatment may play a role, said Dr. Said Ibrahim, the study's lead author and an associate professor at the University of Pittsburgh School of Medicine.

The study also suggested that blacks may be at greater risk because they may be more likely to develop clots in deep veins. And they may respond differently than whites to standard drugs used to treat pulmonary embolism.

Blacks might need to be treated with higher levels of anticoagulant drugs or treated for longer periods, said Dr. Daniel Shade, a pulmonary critical care specialist at Allegheny General Hospital who was not involved in the study.

He said the findings raise questions about whether differences in treatment exist or if there are other differences, such as the tendency to form clots, that might increase the risk of blacks to have worse outcomes.

More than 600,000 people in the United States have a pulmonary embolism each year and more than 60,000 of them die, according to the National Heart, Lung and Blood Institute.

Pulmonary embolism is one of the most common causes of death in hospitalized people who must remain in bed for a long time.

The embolisms often occur when blood clots traveling from the legs cause sudden blockages in lung arteries. Clots can form when blood flow is restricted during surgery, for example, or by sitting for long periods. Medication is available to treat or prevent the clots, and exercising lower leg muscles may help.

Previous studies have suggested higher mortality rates from pulmonary embolisms among blacks, but they did not adjust for health differences among patients or other factors, said Dr. Ibrahim, who is also an executive committee member for VA Pittsburgh's Center for Health Equity Research and Promotion.

The latest study relied on data obtained from the Pennsylvania Health Care Cost Containment Council for more than 14,000 patients with pulmonary embolisms who were treated in hospitals between January 2000 and November 2002.

Mortality rates included patients who died within 30 days of their first admission to the hospital.

Overall, 30-day mortality rates were 9 percent for whites and 10.3 percent for blacks, but the disparity was greater after certain risk factors, such as whether a patient had heart disease or cancer, were taken into account.

Other possible risk factors include insurance status and hospital size, Dr. Ibrahim said. Whether a patient has good health insurance, for example, could affect access to care, and larger hospitals might be more likely to provide better treatment.

The study also considered those factors, but neither was found to be a significant predictor of mortality.

Other co-authors included D. Scott Obrosky, Jennifer Sartorius and Drs. Roslyn Stone and Michael Fine, all of the VA Pittsburgh Healthcare System, and Dr. Drahomir Aujesky of the University of Lausanne, Switzerland.

Researchers are planning another study to assess care for pulmonary embolisms among blacks and whites, Dr. Ibrahim said.

In Pennsylvania and other states, health disparities among blacks and whites have long been recognized.

Compared to white residents, for example, blacks in Pennsylvania are more likely to die from homicide or certain cancers. They also are more likely to smoke, be overweight, or have asthma, diabetes or high blood pressure.

Experts suggest that health disparities might be reduced by broadening access to health care, increasing the cultural competency of health care providers and improving the environments where minorities reside.