By Kara Miller

What are the fastest-growing occupations in the United States? No surprise, there are a lot of tech jobs: Data scientist and information security analyst, for example, both rank in the top five and pay a median salary in the low six figures.

But neither career is as fast-growing or as high-paying as nurse practitioner, an occupation that’s rapidly reshaping American health care. The number of nurse practitioners has nearly quadrupled since 2010, and the profession’s meteoric rise will likely continue. The Bureau of Labor Statistics projects the number of nurse practitioners will grow 40 percent between 2023 and 2033.

Increasingly, though, nurse practitioners are doing work that doctors have historically done, leading to tension between the groups over training, experience, and pay. “One of the most intense and acrimonious, nonpartisan policy debates right now is between MDs and NPs,” notes Michael Barnett, a primary care physician and associate professor of health policy and management at Harvard T.H. Chan School of Public Health.

He says that association which represent doctors, have pushed back hard against the scope of nurse practitioners’ ability to practice because, in part, “there are a lot of MDs that resent the authority that NPs get with a fraction of the training that they have.” And there is a wide range in the quality of nurse practitioner programs, he says. (Nurse practitioners are registered nurses who also complete a master’s of science in nursing or a doctor of nursing practice, which can take from 18 months to four years.)

“You can walk one block in Brookline and find a doc who’s worried,” says Ateev Mehrotra, chair of the department of health services, policy, and practice at the Brown University School of Public Health. And they’ll cite specific incidents in which they feel like NPs didn’t handle something correctly, he says.

A few years ago, Mehrotra sensed that there were more and more nurse practitioners and physician assistants working alongside him in the hospital. But he wanted to try to understand the big picture. So he coauthored a paper looking at 276 million health care visits between 2013 and 2019. He found that by 2019, 42 percent of patients with at least one visit to a health care provider saw a nurse practitioner or a physician assistant.

Mehrotra, who has worked as both a primary care physician and a pediatrician, believes that it’s hard to draw a clear dividing line between the duties of MDs and NPs. He notes that there have been randomized control trials in which some patients were sent to nurse practitioners and some to MDs, and the health outcomes were similar.

David Auerbach, the Massachusetts Health Policy Commission’s senior director for research and cost trends, agrees that when you look at the research around quality of care, most people don’t see a big difference. But he emphasizes that providers are not interchangeable; doctors, for example, often handle more complicated cases.

What nurse practitioners are allowed to do varies from state to state and can come as the result of hard-fought battles. Massachusetts is a “full practice” state — which means NPs can prescribe medications, diagnose, order tests, and oversee treatments — while California and Michigan, for example, are classified as “restricted practice” states.

In some rural areas, nurse practitioners now practice on their own, because doctors are scarce. Per capita, the number of psychiatric nurse practitioners has eclipsed the number of psychiatrists in parts of rural America.

Massachusetts restricted the work of nurse practitioners for a long time, according to Karen Donelan, a professor of US health policy at Brandeis’s Heller School for Social Policy and Management. “They fought full scope of practice for years and years and years,” Donelan says. And she points out that it wasn’t until the pandemic that the state relaxed those restrictions. Massachusetts General Hospital, the largest hospital in the state, now has approximately 800 nurse practitioners and 2,400 physicians.

In the United States, the average annual wage of nurse practitioners is about $130,000, while the average salary for doctors in pediatrics and family medicine is between $200,000 and $250,000. For hospitals looking to save money, hiring more NPs to see patients can serve as a cost-saving measure. (MGH’s nurse practitioners and physician assistants were told in September that they’d receive a 10 percent raise, after the hospital’s nurses received a 13 percent raise.)

Now, lots of patients see nurse practitioners for their annual checkups. In part, this is because the number of physicians in America is not growing quickly enough to meet demand. But it’s also because physicians have eschewed primary care, which doesn’t tend to pay as well as specialties, like cardiology and dermatology. Cardiologists make more than $400,000 a year, on average.

Maggie Sullivan, a lecturer at the Chan School of Public Health who has worked as a nurse practitioner for two decades, says that doctors and nurse practitioners can collaborate effectively. But there are times that doctors — especially those who have never worked alongside nurse practitioners — underestimate what NPs are capable of.

“As a nurse practitioner who’s experienced, it is really frustrating to be working side-by-side with a physician fresh out of residency, who is very much thinking that their training and practice is superior to yours,” she says.

Donelan says that she has seen teams of MDs and NPs work well together — and almost everyone I spoke with echoed that. But she believes the United States has “suppressed the number of physicians that are being produced,” and she argues that there simply aren’t enough of them “to deal with an aging population, mental health issues, substance abuse problems.”

In part, doctors’ concern about the rising number of nurse practitioners may boil down to how different training is for the two professions. “It’s a real pain to get into medical school,” Mehrotra says. “Then you do three years of residency at least. Most are doing more than that. So let’s say you do a total of five years of residency. That’s nine years of your life. And this nurse practitioner, who may have had a much lower number of years — let’s say three years — is working side-by-side with you.” He says doctors want to believe that “those extra six years, and all that pain” are worth it.

Sullivan believes that young doctors do tend to have more experience than young nurse practitioners, because doctors have been through residency. And she says physicians’ salaries reflect more years of education, along with (often) a heavier workload and more responsibility for patient outcomes. But, she says, after some number of years, “you’re going to reach a comparably competent level.”

Certainly, the cost of that additional education may help explain why the number of nurse practitioners has exploded, especially in specialties and areas of the country that pay less for doctors. “If you graduate from medical school,” Sullivan says, “and after residency you have $350,000 in debt, you’re going to go for what pays the best.”

No matter how the turf battles unfold, argues Harvard’s Barnett, the future will inevitably be shaped by “extreme need.” We have a growing number of older Americans, he says, but “the supply of physicians has not kept up and has barely kept up with population growth in the US.”

He believes the rise of NPs is a complicated, nuanced issue, but he predicts that their numbers will likely equal the number of physicians in the next 20 years.

“Nurse practitioners are clearly ascendant in the market,” Barnett says. “And MDs are not doing anything to slow down that enormous economic trend.”