Black people who live in counties with more Black primary care doctors tend to have a higher life expectancy, a new study from American Medical Association finds. It also shines a spotlight on the need for more Black physicians in the U.S. health care system.

The report, published in JAMA Network Open on April 14, was based on a cohort study of 1,618 counties across the nation with at least one Black primary care doctor. Researchers took a snapshot at five-year intervals, in 2009, 2014 and 2019, and found that Black residents’ life expectancy increased with the number of Black primary care physicians in the county.

Interestingly, the Black residents had lower mortality rates whether or not they were patients of the Black doctors. The finding of longer life expectancy persisted even in counties with only one Black physician.

Life expectancy increased slightly more than a month (30.61 days) for every 10 percent increase in Black primary care physicians. Researchers also found that the racial disparity in mortality rate between Black and White Americans decreased by 1.2 percent with every 10 percent increase in the presence of Black primary care doctors.

This study is the first to link increasing the number of Black physicians to the life expectancy of Black Americans, according to STAT, a health and medicine news site.

Researchers didn’t prove a cause-and-effect relationship or shed light on exactly why the presence of a Black doctor in a county impacts life expectancy of Black residents.

Other studies that explain the benefits of having a Black doctor, STAT notes, have found that communication is better between doctors and patients of the same race, Black doctors tend not to hold stereotypes and implicit bias about their Black patients, and they also offer preventive care to Black patients compared to White doctors.

But what explains this new finding that life expectancy increases whether or not Black residents are treated by a Black primary care doctor in their county?

The presence of a Black doctor in a county “may be a marker for living in a community that better supports Black lives,” Dr. John Snyder, one of the study’s lead authors said, according to STAT.

Dr. Monica E. Peek, a primary care physician and health equity researcher at University of Chicago Medicine, offers additional insight.

“There is also evidence that Black physicians are more likely than physicians from other racial or ethnic groups to engage in health-related work outside the health care system—that is, Black physicians are more likely to provide health-related expertise to local community organizations (eg, school boards, local media),” Peek wrote about the study’s finding, adding that Black doctors are likely politically involved in public health issues that affect their community.

The study also revealed that just over half of the counties across the nation don’t have a Black primary care physician.

Only about 5.7 percent of doctors in the United States identify as Black, compared to 6.9 percent Hispanic, 20.6 percent Asian and 63.9 percent White, according to data from the Association of American Medical Colleges published in January.

“This study has brought to light the importance of Black PCP (primary care physician) representation to public health outcomes among Black populations across the US,” Peek wrote. “Increasing this representation must become a multifaceted national strategy to improve health and increase equity among Black populations in the US.”