(Reuters Health) - A growing number of nurse practitioners are providing primary care in rural and low-income U.S. communities where the physician workforce is shrinking, a new study suggests.

Nationwide, primary care doctors outnumber nurse practitioners (NPs) by a wide margin, with almost 244,000 physicians in this field as of 2016 compared with about 123,000 NPs in primary care. That’s up from about 226,000 doctors and 59,000 NPs providing primary care in 2010.

But the primary care physician workforce is flatlining. From 2010 to 2016, the number of available doctors declined by 0.02 for every 100,000 people in the U.S. population while the number of working nurse practitioners increased by three for every 100,000 people.

On average, the nation’s largest metropolitan areas added 2.9 more nurse practitioners than doctors for every 100,000 residents and rural communities added 4.3 more nurses than physicians.

Rural and poor communities have long suffered from a lack of access to primary care providers as well as specialists, shortages that have been tied to a variety of health disparities, researchers note in JAMA.

“The growing NP supply in these areas is offsetting low physician supply and thus may increase primary care capacity in underserved communities,” said lead study author Ying Xue of the University of Rochester School of Nursing in New York, in an email.

To assess the primary care workforce, researchers examined U.S. census data as well as data on the physician workforce from the American Medical Association, plus Medicare billing records on doctors and nurses providing primary care.

During the study period, the average number of nurse practitioners in communities with the most low-income residents rose from 19.8 to 41.1 for every 100,000 people, while the average number of physicians dipped from 52.9 to 52 for every 100,000 people.

Over that same time, the average number of nurse practitioners serving rural communities rose from 25.2 to 41.3 for every 100,000 people, while the average number of physicians dropped from 59.5 to 47.8 for every 100,000 people.

The study doesn’t show whether or how shifts in the primary care workforce might directly impact the accessibility, affordability or quality of care. And it wasn’t designed to explain why the proportion of doctors and nurses working in primary care is changing.

“This study doesn’t answer whether or not an NP is a good substitute for a physician in the population overall and for any given patient,” said Dr. Anupam Jena of Harvard Medical School and Massachusetts General Hospital in Boston, in an email.

Some previous research suggests that doctors and nurse practitioners can provide similar quality primary care, said Jena, who wasn’t involved in the study. Some patients with complicated medical issues that are difficult to diagnose may want to see physicians, but research to date hasn’t offered a clear picture of whether doctors are better than NPs for these individuals, Jena added.

“Ultimately, if patients feel that their care needs aren’t being met, it’s time to switch providers, whether that be from or to a doctor or NP,” Jena said.

SOURCE: bit.ly/2CYakDA JAMA, online January 8, 2019.