In telephone interviews with 527 African American and 382 white people, researchers found that while 41.7 percent of whites said they trust their physician to fully explain the risks and benefits of research study participation, only 23.4 percent of African Americans trust their doctors to do the same.

More than 45 percent of African Americans said that their physicians exposed them to unnecessary risks compared with 34.8 percent of whites. African Americans had a significantly higher mean distrust index score than white respondents (3.1 versus 1.8). Race remained strongly associated with a greater distrust of physicians even after researchers controlled for other sociodemographic factors.

"Even after controlling for markers of social class, African Americans were less trusting than white Americans," the study authors wrote. "Racial differences in distrust have important implications for investigators as they engage African Americans in research."

Findings from the study, conducted in part to understand why it is more difficult to recruit and enroll African Americans in research studies, was published in the November 25th issue of the Archives of Internal Medicine.

"Ongoing community involvement is not only important in building trust but also allows the investigator an opportunity to better understand the barriers and challenges that are specific to that community," the study authors wrote.

In a study published in the same journal in December of 2000, researchers wrote that, "While pervasive racial and ethnic inequalities in access to care and health status have been documented, potential underlying causes, such as patients' perceptions of their physicians, have not been explored as thoroughly."

After adjusting for other socioeconomic factors, in this particular study, researchers also found that minority groups reported less positive perceptions of physicians than whites.