NP & PA vs MD & DO | Midlevel Encroachment [Research Explained]


In the world of medicine, nothing is as hotly debated as the issue of the scope of practice for nurse practitioners and physician assistants, also referred to as advanced practice providers or mid-levels. Here’s what the scientific literature has to say about independent practice for nurse practitioners and physician assistants, and how their care compares to that of physicians.


Arguments Supporting Independent Practice

There are several arguments in support of independent practice for midlevel providers.

The first is that PAs and NPs have sufficient training to treat patients independently and without the need for a supervising physician. To become an NP, one must hold a bachelor’s degree in nursing, be licensed as a registered nurse, graduate from a nationally accredited graduate NP program and pass a national NP board certification exam.

Similarly, physician assistants must complete a bachelor’s degree, complete a nationally accredited physician assistant program, meet national standards, and pass a board certification exam.

In addition, many states that currently allow for independent practice require a certain number of hours or number of years working underneath a supervising physician before APPs can practice independently.

The American Association of Nurse Practitioners argues that “a head-to-head comparison of educational models is not the appropriate measure of clinical success or patient safety.” Nurse Practitioner education is competency-based, not time-based, meaning that NP students don’t progress or graduate based on the number of hours spent in a rotation or by the number of times they’ve seen a particular ailment, rather they do so when knowledge and skill competency are achieved.

Some argue that mid-levels also have experience before graduate level training as a PA or NP which often includes physical assessment skills, interpreting diagnostic test results, evaluating the appropriateness of medications, and evaluating patients’ response to treatments.

There are also a number of studies comparing outcomes between physicians and midlevel providers in support of independent practice.

A 2018 study examined the relationship between primary care provider type and diabetes outcomes among patients and found no clinically significant differences between the three provider types in terms of diabetes outcomes. The authors suggest that similar chronic illness outcomes may be achieved by physicians, NPs, and PAs.

In addition, a 2021 meta-analysis of 39 different studies found that the quality of care delivered by the PA was comparable to a physician’s in 15 studies and exceeded that of a physician in 18 studies.

Another argument in favor of independent practice is that it improves access to care. As it stands in the United States, we have a shortage of physicians – specifically in primary care specialties. According to the AAMC, we can expect shortages of between approximately 38,000 and 124,000 physicians by the year 2034.

By granting independent practice to PAs and NPs, some argue that we can help offset the growing demand for physicians, especially in underserved areas.

A 2016 study compared the geographic accessibility of primary care clinicians between states with more restrictive and less restrictive scope-of-practice laws. They found that access to primary care nurse practitioners was highest in rural areas and that less-restrictive scope-of-practice states had as much as 40% more primary care nurse practitioners compared to more restrictive states. They concluded that removing restrictive scope-of-practice laws may help to expand the overall capacity of the primary care workforce.

Lastly, proponents of independent practice argue that PAs and NPs can help decrease healthcare costs.

In the same 2021 meta-analysis, the authors found that in 29 out of 39 studies, the labor and resource costs were lower when the PA delivered care compared to when the physician delivered care.

This makes sense as PAs and NPs make substantially less than physicians. According to the Bureau of Labor Statistics, the average PA makes approximately $122,000 per year and the average NP makes approximately $118,000 per year. The average physician, by comparison, makes around $208,000 per year according to the BLS. As a result, it costs hospitals far less to employ APPs than it does to employ physicians.

In addition, a 2021 study found that the average primary care physician’s cost of care is 34% higher than primary care nurse practitioners in low-risk patients, 28% higher in medium-risk patients, and 21% higher in high-risk patients. They conclude that these differences mostly reflect the lower quantity of services provided by primary care NPs relative to primary care MDs which is reflected most in low-risk populations.


Arguments Against Independent Practice

Now let’s talk about the arguments against independent practice.

The primary argument against independent practice is that mid-level providers do not have sufficient training to see patients without a supervising physician.

The average family medicine physician fresh out of residency will have over 20,000 hours of graduate-level training including over 15,000 hours of clinical experience. If we compare this to the average nurse practitioner at the point of certification, they will have received anywhere from 3,000 to 5,500 hours of graduate-level training and only 500 to 1,500 hours of clinical experience.

If we factor in the 2,000-4,000 hours of practice underneath a supervising physician that many states require for independent practice, NPs still have less than half of the clinical hours of a newly-licensed physician. This is also assuming that clinical practice as an NP under the supervision of a physician is equal to that of a resident physician being trained to practice independently.

Physicians are trained with the goal of independent practice from day one. They go into their training knowing that they’ll be on their own one day and won’t be able to rely on anyone else for guidance. They need to be confident in their knowledge and skills in order to make the right decision as they’ll ultimately have to live with the consequences of those decisions.

In contrast, PAs and NPs are not typically trained to practice independently. Although they still treat patients and make decisions on a daily basis, they are doing so with the knowledge that they have a supervising physician to fall back on for guidance. As such, there’s a different level of responsibility and accountability that is put on doctors during their training that you don’t get with PAs or NPs who are trained to work in a more collaborative manner.

There is also a great deal of variability in the training of midlevel providers, especially among nurse practitioners.

There have been dramatic increases in the number of nurse practitioner programs over the last decade with many programs promising quick certification and high acceptance rates. The average acceptance rate for NP programs is estimated to be around 66%.

However, there are multiple NP programs in the US with 100% acceptance rates. By comparison, the acceptance rate for the average medical school is only around 6.5%. These high acceptance rates have brought into question whether the goal of these NP programs is to produce high-quality providers or to make money.

There is also a great deal of variability in the clinical experience between different NP schools. Many schools are 100% online and do not organize the clinical hours required as a part of their curriculum. Instead, it is up to the student to arrange for their own clinical experiences. As a result, it is difficult to ensure consistent, high-quality training among NPs in these programs.

Those that oppose independent practice argue that his disparity in training leads to issues of patient safety, especially in primary care – the field with the biggest push for independent practice for mid-level providers.

Contrary to popular belief, primary care is one of the medical specialties that requires the broadest knowledge. Whereas in other specialties your knowledge becomes increasingly specialized as you progress through training, primary care physicians continue to use and develop the vast information they learned during medical school.

There are a number of research papers supporting this difference in the quality of care between physicians and midlevel providers as well.

A 2018 study found that “compared to dermatologists, PAs performed more skin biopsies per case of skin cancer and they diagnosed fewer melanomas in situ, suggesting the diagnostic accuracy of PAs may be lower than that of dermatologists.”

Studies from 2005 and 2016 also demonstrated that NPs and PAs were more likely to inappropriately prescribe antibiotics than residents and attending physicians, which can contribute to population-level issues such as antibiotic resistance and the creation of superbugs.

In addition, many of the studies that show that NPs and PAs deliver a similar quality of care as physicians do not assess PAs and NPs working independently, but rather those working as part of a healthcare team. As such, it’s a big stretch to draw conclusions about independent practice when you’re looking at studies with non-independently practicing mid-levels.

Another argument is that independent practice increases healthcare costs despite APPs lower cost for services. Many physicians argue that mid-level providers order more unnecessary tests and have to refer patients out to other physicians more frequently. An issue that may have been handled by a primary care physician may now have to be referred out leading to two separate visits instead of just one.

A 2013 article found that the “quality of referrals to an academic medical center was higher for physicians than for mid-level providers regarding the clarity of the referral question, understanding of the pathophysiology, and adequate pre-referral evaluation and documentation.” Referrals from physicians were also less likely to be evaluated as “unnecessary.”

In terms of cost, a 2015 study also showed that mid-levels are associated with ordering more imaging services than PCPs for similar patients. While these increases were modest for individual patients, the authors conclude that these increases may be problematic for patient care and overall costs at the population level.

What Does Scientific Literature Say in 2022?

A recent study published in 2022 in the Journal of the Mississippi State Medical Association summarizes all of these points nicely. The study compared physicians and independently practicing mid-levels in terms of healthcare costs, patient outcomes, and patient satisfaction. They collected data over 10 years from over 300 physicians, 150 APPs, 200,000 patient surveys, and 33,000 unique Medicare beneficiaries. Here’s what they found.

To start, healthcare costs for Medicare patients were $43 higher per month for patients whose primary care provider was a mid-level instead of a doctor. They estimated that this would equate to roughly 10.3 million dollars per year in increased spending if all patients in their clinic were seen by APPs instead of physicians.

When they adjusted these findings for patient complexity, the difference was $119 per patient or 28.5 million dollars annually. They found that these additional costs had to do with several factors, including increased ordering of tests and images, more referrals to specialists, and higher emergency department utilization compared to patients under the care of a physician.

In terms of patient outcomes, physicians outperformed mid-levels on nine out of ten quality metrics including cancer screenings and management of chronic diseases such as high blood pressure and diabetes. Physicians were also found to have higher patient satisfaction scores compared to mid-levels.

The authors also tracked outcomes and cost data from patients who were co-managed by a physician and an APP and found that patients who alternated visits with the physician and the APP had the best quality and cost outcomes of all.

They concluded that, although APPs are an invaluable part of the healthcare team, they are best utilized when they are co-managing patients alongside physicians as opposed to practicing independently. The Hattiesburg Clinic has since redesigned its care model so that a doctor is the primary care physician for all patients and no one sees a nonphysician exclusively.

Although this is just one clinic, in one state, this is one of the first studies that has collected robust data comparing healthcare costs, patient outcomes, and other metrics between physicians and independently practicing mid-level providers. Many previous studies have only compared outcomes between physicians and APPs when functioning in a collaborative role with physicians.

Although NPs and PAs are important members of the healthcare team, the solution to the physician shortage is not to expand their scope and grant them independent practice. The bigger issues that need to be addressed are the limitations preventing us from training more doctors.

There is no shortage of people interested in becoming physicians. We can see this in the record number of applicants applying to medical schools this past cycle. The issue is that there is a bottleneck in the number of residency spots due to the lack of Medicare funding for new residency programs.

According to the NBME, in 2022 there were approximately 43,000 medical students that applied for first-year resident positions, out of which only 34,000 matched. That means that approximately 9,000 medical students will either have to apply for the Supplemental Offer and Acceptance Program and compete for one of the roughly 2,000 residency spots that went unfilled or spend a year strengthening their application so they can reapply next year.

Regardless, roughly 7,000 students who have completed medical school will not be able to progress to the next step of physician training. As such, medical schools cannot continue to expand class sizes as there aren’t enough residency spots to accommodate their graduating students.

This is the real problem and what we need to focus on to address the physician shortage.

At the end of the day, when discussing the issue of mid-level encroachment and independent practice, you should not adopt an us versus them mentality. Physician assistants and nurse practitioners are valuable members of the healthcare team. That being said, they are at their best when functioning how their positions were intended – in a collaborative role, managing patients alongside physicians, not instead of them.

If you enjoyed this article, be sure to check out So You Want to Be a Nurse Practitioner or So You Want to Be a Physician Assistant.

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