Many of us — including myself — are struggling to find a doctor these days. 

Several of my co-residents and I have opted instead to seek our primary care from nurse practitioners or physician assistants. They seem much more likely than doctors to be accepting new patients, at least in the Boston area where we live.

In today’s Research Corner, a creative new study shows my friends and I aren’t the only ones making this switch.

A Quarter of Clinic Visits are no Longer with Doctors

A new analysis of Medicare data published in The BMJ found that by the end of last decade, 1 out of every 4 clinic patients was getting health care from a nurse practitioner (NP) or physician assistant (PA). That’s significantly up from the share of patients (16%) seen by these types of clinicians in 2014.

The study — authored by Sadiq Patel, Ateev Mehrotra and colleagues — also found this growth was uneven across different groups of patients. For example, people who had lower incomes, disabilities or who lived in rural areas were the ones most likely to get their primary care from NPs or PAs. This type of visit also soared by 200% in nursing homes and other assisted living facilities.

While this study only analyzed Medicare data, at least one other looking at claims from commercial insurers suggests this trend away from doctors is broader. That analysis, conducted by the Health Care Cost Institute, found that from 2012 to 2016, office visits to primary care physicians declined by 18%, while office visits to NPs and PAs ballooned by 129%.

NPs and PAs train for less time than physicians do, but are authorized to diagnose, treat and prescribe medications, with different amounts of supervision from doctors required by different states. (In many states NPs can practice independently.) So their rapidly growing role in health care adds new urgency to researchers’ need to answer a longstanding question: How does the cost and quality of care that these practitioners provide compare to the care delivered by physicians?

In many situations, the quality of care provided seems at least as good, though some studies have found instances of practitioners with less medical training delivering worse outcomes. The relative cost or savings to insurers when NPs and PAs provide care is less clear. 

Research limitations obscure the impact of NPs and PAs across the United States

Policymakers would benefit from having a stronger body of evidence, with larger and more robust studies comparing the care delivered by these different types of providers. That’s a need that MedPAC, a committee that recommends policies to Congress, underscored in a 2019 report on this topic.

One of the biggest barriers to getting better data: Figuring out who is actually delivering the care in a given office visit is surprisingly difficult.

For decades, Medicare and private insurers have allowed NPs and PAs to bill under the label of their supervising physician, making it appear on paper — in most analyses of billing data — as though the doctor delivered the care. This practice, known as indirect billing, can be profitable for health systems, which can make more money when a visit is conducted by a lower-paid clinician but reimbursed at the higher rate a physician commands.

Since health care researchers often use billing data when making comparisons among clinicians, this overlapping billing clouds researchers’ ability to make accurate comparisons around cost and quality among physicians, NPs and PAs.

The authors of this recent study in The BMJ found a creative workaround. Instead of just looking at who billed for a health visit, they looked instead to see who the main prescriber was at every visit — since the clinician prescribing something is usually the person leading the appointment.

“They did as clever a job as I have seen trying to overcome the indirect billing problem, which is why I feel these numbers ended up being bigger than what we’ve seen in previous studies,” said Joanne Spetz, a health policy professor at the University of California San Francisco, who wasn’t involved in the study.

However, even the study’s authors acknowledge their methodological workaround is imperfect. A much simpler solution would be to eliminate the use of indirect billing entirely. “Then we don’t have to play this silly game,” study author Ateev Mehrotra, a health care policy professor at Harvard Medical School, told me.

That’s a policy recommendation that MedPAC has previously made to Congress, warning that if allowed to continue, indirect billing will “increasingly obscure policymakers’ knowledge of who provides care to Medicare beneficiaries.”

This change, of course, would not solve all the shortcomings of this area of research, but it would certainly be a big step forward. As the role of NPs and PAs continues to rapidly expand, researchers need all the help they can get in monitoring this massive shift in who delivers health care in the U.S., and what that means for patients and insurers alike.