Black, Latino and Asian patients admitted to emergency rooms who are in significant pain are less likely than white patients to be prescribed a narcotic to ease the pain, new research reports.

Researchers at the University of California, San Francisco, examined reports about emergency room visits between 1993 and 2005. They found that while doctors have started prescribing powerful painkillers, such as morphine, codeine, oxcodone and Vicodin more often in recent years, white patients were more likely to receive them than patients of other races. In 2005, for example, white patients who needed painkillers received them 40 percent of the time, versus 32 percent for members of other races.

Researchers say that these discrepancies could be due to a number of factors, including racial bias, language barriers and a lack of empowerment among patients of minority groups to demand painkillers.