Secondary Logo

Journal Logo


Pathways to Independent Primary Care Clinical Practice: How Tall Is the Shortest Giant?

Dewan, Mantosh J. MD; Norcini, John J. PhD

Author Information
doi: 10.1097/ACM.0000000000002764
  • Free


Historically, physicians were playfully considered “giants” because of the extensive education and training required to practice medicine. A broader range of primary care practitioners now loom large in their patients’ lives. These giants offer treatment including evaluation, ordering and reviewing tests, procedures, and writing prescriptions. Today, a patient seeking primary care can be seen by one of three types of practitioners in a primary care practice: a physician, a nurse practitioner (NP), or a physician assistant (PA, who may discuss care plans with a “supervising physician”). Each duly licensed provider has arrived at this point of practice via different paths, creating a natural experiment that allows us to focus on an infrequently asked but critical question: What is the minimum education and training required to practice primary care clinical medicine?

Comparing the Shortest Paths to Independent Practice

Training paths vary widely even within disciplines. Here we distill the minimum requirements to become a physician, a nurse practitioner, and a physician assistant, by which we mean the total number of training years, including required supervised clinical experiences (SCEs) collated in weeks (Table 1).

Table 1:
Minimum Training Requirements for Licensure for Primary Care Physicians, Nurse Practitioners, and Physician Assistants


License to practice as a physician requires a bachelor’s degree, a medical degree, and residency training. The bachelor’s degree takes four years and requires no SCE. Although the vast majority of medical schools are four-year programs, we accept three years as the minimum duration of the medical degree requirement for a physician, since there are some accredited three-year schools. A three-year medical school must have the minimum Liaison Committee on Medical Education–required 130 contact weeks.1 Curricula reflect the time-honored Flexnerian formula (half basic sciences, half clinical),2 so we accept 65 weeks of SCE. Finally, one year of residency is the least that is required for licensure; some states require more.3 For this year we accept a conservative minimum of 45 weeks, with each week being 40 hours, and ignore the fact that most residents work long hours and do night call. We recognize that the Accreditation Council for Graduate Medical Education requires the average to be less than 80 hours per week.4 Eighty hours per week would make the one-year residency worth 90 weeks, but we intentionally reduce it to 45 weeks of 40 hours because we are estimating minimums. Therefore, to be licensed and practice independently as a physician takes a minimum of 8 years, which includes 110 weeks of SCE (Table 1).


License to practice as an NP requires an associate’s degree in nursing (ADN), a registered nurse (RN) license, a bachelor of science degree in nursing (BSN), and a master’s degree in nursing. The ADN takes two years, but accrediting bodies do not set a minimum number of clinical hours. We queried several programs in different states and found that the minimum SCE was about 15 weeks.5,6 A rigorous search may turn up a program with even lower requirements, but 15 weeks was consistent across the few we interrogated. Passing an examination bestows an RN license. Numerous entirely online courses upgrade the ADN to a BSN; these take two years, and no SCE is required or often even offered.7 Nurses commonly work in a clinical setting while obtaining their BSN; however, we disregard this because you can complete a BSN full-time without any SCE. Finally, the master’s-level NP program is two years and requires “at least 500 hours” (or 12.5 weeks) of SCE.8 NP programs typically prefer two years of clinical experience, but this is not required. Therefore, to be licensed and practice independently as an NP takes a minimum of six years, which includes 27.5 weeks of SCE (Table 1).


PAs practice not independently but autonomously (i.e., with physician supervision, which could be minimal). License to practice as a PA requires a bachelor’s degree and a master’s degree in a PA program. As with premedical students, the bachelor’s degree takes four years and requires no SCE. As with NP programs, PA programs prefer that applicants have had clinical experience, but this is not required. PA programs last two years, with one being clinical, which equates to 45 weeks of SCE. Therefore, to be licensed and practice autonomously but not independently as a PA takes a minimum of six years, which includes 45 weeks of SCE (Table 1).

How Tall Is the Shortest Giant?

Three very different education and training paths lead to a license to practice as a primary care “giant” in patient care. But what is the minimum education and training required for the safe, independent practice of clinical medicine? In more colorful terms, how tall is the shortest giant? Educational systems have chosen not to address this. They do not consistently prescribe specific minimums for the content of the curriculum or the quality and quantity of the clinical experience. However, individual states have stepped in to license these giants and legislate their scope of practice, leading to considerable variability. Twenty-two states9 have declared NPs to be giants, thus establishing 6 years with 27.5 weeks of SCE as the minimum training needed to evaluate and treat patients independently.

Comparing the three giants

If the minimum training required for independent practice of primary care as an NP is 6 years and 27.5 weeks of SCE, what is the advantage or necessity for a primary care physician to train for 8 years with 110 weeks of SCE to achieve the same level? What is the justification for granting autonomous but not independent practice to a PA with more training (6 years and 45 weeks) than an NP who can practice independently? These pointed questions become even more pertinent if there is evidence that all three professions practice safely and have comparable patient outcomes.

A number of reviews suggest that NPs provide care indistinguishable from that provided by physicians.10–14 This conclusion is supported by at least four randomized controlled trials (RCTs)15–18 and a number of less rigorous studies that show that NPs provide equivalent quality of care for patients with asthma,15 diabetes,15,19,20 depression,19 hypertension,15 backache,21 headache,21 hypercholesteremia,19 upper respiratory infection,21 and HIV.22 NPs can serve interchangeably with physicians and residents even in specialized services such as the medical intensive care unit23 and surgical intensive care unit24; lead critical response teams25; and perform endoscopies.26 Whereas some studies have patient outcome measures,15–17 most use quality process measures,15,19,21 tracking prescription of an antidepressant or statin, or measures of resource utilization15 or patient satisfaction.15

There are fewer reviews25,26 and studies19,20,22,27 (and no RCTs) of PA performance. They too indicate equivalence in quality process measures for patients in primary care (e.g., with depression,19 diabetes,20 hypercholesteremia,19 HIV22) and for patient satisfaction.26

There are very few studies that are not supportive, raising the issue of publication bias. One finds that PAs and NPs prescribe antibiotics inappropriately more often than physicians28; another suggests that the diagnostic accuracy of PAs may be lower than that of dermatologists for some forms of skin cancer.29

The overall indication that there is no distinguishable difference between primary care physicians and NPs and PAs is particularly impressive since physicians in these studies presumably had trained for 11 years (4 years for the bachelor’s degree, 4 years of medical school, 3 years of residency) with 225 weeks of SCE (eight times the minimum SCE required of NPs)—far more than the minimum training required for physicians of 8 years and 110 weeks of SCE. We assume that this is because the vast majority of physicians graduate from 4-year schools and complete 3 years of residency, which is the standard length for internal medicine and family practice residencies—there are almost no primary care physicians who completed just 1 year of residency.

On the other hand, many of these studies have marked deficiencies. Some have been criticized for not being RCTs or for having a small sample size (e.g., two MDs and two NPs),17 which makes it more likely that differences will not be detected. Other criticisms include using quality process rather than patient outcome measures, and allowing NPs and PAs to have a narrow range and fewer patients per day—and therefore more time with each patient—than their physician counterparts, which likely influences patient satisfaction, patient education, and patient outcomes. A recent publication exemplifies the difficulty in making comparisons between professions even when using large datasets with objective numbers. It concludes, “The latest 10 years of observation [of the National Practitioner Data Bank] is consistent with reports that PAs and NPs have lower reports of liability relative to their physician colleagues.”30(p11) However:

This result may be partially explained by the presence of surgeons and anesthesiologists in the physician group … by differences in the number of patients seen and breadth of patient acuity. Under the doctrine of respondent superior, a plaintiff may hold the physician, as a supervisor, accountable for the actions of his or her employees.30(p9)

The groups are not comparable, and firm conclusions are not warranted.

Clearly, the current level of evidence is poor, and no meaningful statement can be made regarding equivalence among physicians, NPs, and PAs. There is an urgent need for larger, more rigorous studies to confirm the appropriate height of the shortest giant. Future research should be adequately powered; should take the form of RCTs; should ensure that NPs and PAs are indeed practicing independently with comparable numbers, acuity, and range of patients to their physician counterparts; and should use meaningful patient outcome measures such as HbA1c or a validated depression rating scale rather than a quality process measure such as “prescribed an antidepressant.” It is also important to categorize and distinguish outcomes for first-generation NPs who are usually midcareer, experienced clinicians from those of newer, “fast track” and inexperienced graduates. To most accurately determine the effect of differences in training, it may be best to study outcomes of all three groups within a year of graduation. This will eliminate two confounding variables: (1) improvements attributable to experience which militates against (2) evidence that patient outcomes and other markers of performance decline with increasing time since training.31,32

Implications for the education of physicians

What do these data tell us about the education of physicians? There are just a handful of 3-year medical schools, and almost no physicians practice after just a year of residency; the vast majority of primary care physicians (internal medicine or family practice) have spent 11 years in training, with 225 weeks (4.5 years) of supervised patient contact when the minimum legislated for clinical practice is 6 years and 27.5 weeks (half a year). If further studies confirm that the pathway to practice for the shortest giant (6 years, 27.5 weeks) is as effective as that for the tallest giant (11 years, 225 weeks), there must be a serious reevaluation of the length and especially the content of medical training. Equivalence in patient outcomes among different primary care practitioners is more persuasive than some of the reasons driving the push toward 3-year medical schools (e.g., medical training is too long and expensive),33 reasons which are divorced from quality of care.

An even more challenging question is whether a two-year medical school can be a satisfactory pathway to a rigorous residency. As ten Cate34(p966) points out:

Abraham Flexner, reporting a century ago about the state of U.S. and European medical education, did not yet mention internships or any hospital training after graduation. This reflected the prevailing practice of relying on undergraduate medical education as sufficient preparation for lifelong medical practice.… In the 21st century the medical degree, while still significant in its legal status, has become an intermediate station in a long educational trajectory, rather than an end point.”

He concludes that “the purpose of medical training has moved from readiness for independent medical practice to readiness for postgraduate training.”35(p7) Postgraduate training today is in fact supervised practice and training after four years in medical school. A PA education also leads to supervised practice in any specialty, but PAs arrive at this point after just two years of education. Could the equivalent of this two-year PA education for medical students be an accepted minimum for residency in a primary care specialty?

On the other hand, if this equivalence does not hold up, then we need to use data to revise the minimum requirements to be the shortest giant. This may include increased SCE (the availability of which even now is a rate-limiting step in many programs) or requiring an NP or PA residency, which are currently unregulated, voluntary, and last just one year. If these are needed, how long should they be?

Irrespective, there needs to be an analysis of the length and particularly the content of training for each of the practice professions as part of the next phase of work. For instance, given the fact that physicians’ SCE (4.5 years) is eight times that of NPs (half a year) but that studies show equivalent patient outcomes, what is the minimum SCE needed for independent primary care practice? Are there approaches and pedagogies that enable a shorter curriculum in nursing education? Can these best practices be adopted by medical educators to make medical training more efficient?

Is scope of practice the solution?

In addition to reevaluating minimum requirements of education and training, it would be beneficial to match scope of practice to training more transparently. Scope of practice defines “the rules, the regulations, and the boundaries within which a fully qualified practitioner with substantial and appropriate training, knowledge, and experience may practice in a field of medicine or surgery” (emphasis added).36 Given the significant differences in training amongst physicians, NPs, and PAs, it is reasonable to expect that each group has valuable but differing skills that should define contours of practice. Currently, scope of practice is ill defined, and it is up to the individual practitioner to establish boundaries (e.g., what procedures to perform, when to refer, or when to seek supervision). There is an urgent need to use objective measures to rationalize the scope of practice at each level for the three primary care professions.

For instance, it has been noted that primary care physicians actually perform fewer procedures than they are trained to do; the only area in which they exceed their training is in psychiatric disorders.37 Could this allow for an intentional narrowing of scope of practice and concomitant shortening of training? On the other hand, Sweigart et al38 found that “[h]alf of the rural hospitalists who were primary physicians for [intensive care unit] patients felt obliged to practice beyond their scope.” This and the need to be more mindful of new areas such as population health have led to increasing the length of the primary care residency at Oregon Health and Sciences University from 3 years to 4 years. This is part of the American Medical Association’s Accelerating Change in Medical Education initiative to adequately prepare primary care physicians for the challenges of work in the 21st century.39 The medical education community has not taken on the challenge of defining the training and scope of practice of the shortest physician giant; instead, the focus is more easily on adding requirements and creating the tallest giant. On the other hand, exciting steps are being taken to define and assess minimum competencies in time-variable training programs.40,41 These need to be married to meaningful clinical outcomes.42

In a 2010 report, the Institute of Medicine urged that “advanced practice registered nurses should be able to practice to the full extent of their education and training.”43(p4) This must apply to all practitioners. If political considerations are replaced with a purely evidence-based approach, two truths emerge: (1) PAs (6 years of education; 45 weeks of SCE) are taller than the shortest giants (NPs with 6 years of education and 27.5 weeks of SCE) and have earned the right to practice independently. Currently, they have a restricted license to practice autonomously with physician supervision. (2) Physicians graduating from a 3-year medical school (7 years; 65 weeks) or after completing their third year in a 4-year medical school (7 years; 45 weeks) have grown enough: They too are taller than the shortest giant and capable of independent practice. Although already the tallest giant on graduating from either a 3-year or 4-year school, physicians must complete at least 1 additional year of residency with another 45 weeks of SCE to be licensed to practice independently. The data suggest this is unnecessary and support changes with three major positive consequences.

First, medical students entering their fourth year have enough training (7 years of education; 45 weeks of SCE) to warrant them practicing independently. We can use the well-documented positive experiences with longitudinal integrated clerkships in the third year to model a fourth year consisting of an independent primary care practice within an interprofessional team with a collaborating senior faculty physician. This will serve two important purposes: (1) markedly improve clinical expertise and confidence and (2) allow, for the first time, evaluation of graduates using not just educational outcomes but also the more meaningful patient outcomes to certify competence.44

Second, obtaining a residency is the rate-limiting step, and in recent years thousands of U.S. citizens with U.S. and international medical degrees are unable to practice because they did not match. For instance, 4,099 applicants (including 1,078 U.S. allopathic medical school seniors, 846 students/graduates of U.S. osteopathic medical schools, and 2,175 U.S. citizen students/graduates of international medical schools) in 2018 and 4,008 in 2017 failed to obtain a postgraduate year one position in the main residency Match; some will get positions subsequently in the Supplemental Offer and Acceptance Program or after the Match.45,46 Granting independent practice privileges to these thousands of physician giants every year would put a distinct and immediate dent in the doctor shortage.

Finally, several states have licensed these unmatched physicians as “assistant physicians” (distinct from physicians and PAs). They are allowed to practice under supervision for a limited number of years (two or three) and only in underserved areas, where there is a chronic and severe shortage of providers.47 This unfairly penalizes them on multiple counts: they are taller than the shortest giant and should be licensed independent physicians, not assistant physicians, and their practice should not be restricted to a limited period or to underserved areas since no other giant carries this burden.

Next Steps

There is a marked shortage of primary care physicians,48 which is aggravated by the absence of much-needed non-residency-trained general practitioners who are the staple of health care systems throughout the world except in the United States. This urgent need has led to the rapidly increasing number of invaluable primary care NPs and PAs with a quickly increasing scope of practice, including the advancement of statewide specialty systems serviced primarily by NPs.49 This expansion and independence—supported by encouraging but flawed initial studies showing equivalence of outcomes between physicians, NPs, and PAs—will likely continue to grow. NPs will conceivably be able to practice independently in all states, and PAs could get similar privileges despite strong opposition from individual physicians and organized medicine.50 This has major implications for health care policy, quality of patient care, and interprofessional relationships. We suggest setting aside preconceived notions and turf battles to urgently generate meaningful data on practice patterns and patient outcomes. This can be used to refine optimal training requirements for each discipline, delineate scope of practice to honor the full extent of each discipline’s education and training (which are very different), and build interprofessional teams that are respectful and function at levels that are better than their individual parts.20


1. Liaison Committee on Medical Education. Functions and structure of a medical school: 2018–19. Published March 2017. Accessed April 12, 2019.
2. Flexner A. Medical Education in the United States and Canada: A Report to the Carnegie Foundation for the Advancement of Teaching. Bulletin No. 4. 1910.Boston, MA: Updyke.
3. State-specific requirements for initial medical licensure. Accessed April 12, 2019.
4. Burchiel KJ, Zetterman RK, Ludmerer KM, et al. The 2017 ACGME common work hour standards: Promoting physician learning and professional development in a safe, humane environment. J Grad Med Educ. 2017;9:692–696.
5. Alfieri L. Director of Nursing, Cayuga Community College, February 1, 2018.Auburn, NY. Personal communication with M. Dewan.
6. LaMartina. Dean of Nursing, Johnson County Community College, February 10, 2018.Kansas. Personal communication with M. Dewan.
7. Best College Reviews. The 25 best RN to BSN programs online for 2019. Accessed April 12, 2019.
8. Kansas State Board of Nursing. Nurse Practitioner Act Statutes and Administrative Regulations. Advanced Nursing Education Program Curricular Requirements. April 2016.Topeka, KS: Kansas State Board of Nursing.
9. Chesney ML, Duderstadt KG. States’ progress toward nurse practitioner full practice authority: Contemporary challenges and strategies. J Pediatr Health Care. 2017;31:724–728.
10. U.S. Congress, Office of Technology Assessment. NPs, PAs, and Certified Nurse Midwives: A Policy Analysis. 1986. Washington, DC: U.S. Government Printing Office; Accessed April 12, 2019.
11. Naylor MD, Kurtzman ET. The role of nurse practitioners in reinventing primary care. Health Aff (Millwood). 2010;29:893–899.
12. Stanik-Hutt J, Newhouse RP, White KM, et al. The quality and effectiveness of care provided by nurse practitioners. J Nurse Pract. 2013;9:492–500.
13. Hooker RS, Everett CM. The contributions of physician assistants in primary care systems. Health Soc Care Community. 2012;20:20–31.
14. Halter M, Drennan V, Chattopadhyay K, et al. The contribution of physician assistants in primary care: A systematic review. BMC Health Serv Res. 2013;13:223.
15. Mundinger MO, Kane RL, Lenz ER, et al. Primary care outcomes in patients treated by nurse practitioners or physicians: A randomized trial. JAMA. 2000;283:59–68.
16. Lenz ER, Mundinger MO, Kane RL, Hopkins SC, Lin SX. Primary care outcomes in patients treated by nurse practitioners or physicians: Two-year follow-up. Med Care Res Rev. 2004;61:332–351.
17. Sackett DL, Spitzer WO, Gent M, Roberts RS. The Burlington randomized trial of the nurse practitioner: Health outcomes of patients. Ann Intern Med. 1974;80:137–142.
18. Dierick-van Daele AT, Metsemakers JF, Derckx EW, Spreeuwenberg C, Vrijhoef HJ. Nurse practitioners substituting for general practitioners: Randomized controlled trial. J Adv Nurs. 2009;65:391–401.
19. Kurtzman ET, Barnow BS. A comparison of nurse practitioners, physician assistants, and primary care physicians’ patterns of practice and quality of care in health centers. Med Care. 2017;55:615–622.
20. Ohman-Strickland PA, Orzano AJ, Hudson SV, et al. Quality of diabetes care in family medicine practices: Influence of nurse-practitioners and physician’s assistants. Ann Fam Med. 2008;6:14–22.
21. Mafi JN, Wee CC, Davis RB, Landon BE. Comparing use of low-value health care services among U.S. advanced practice clinicians and physicians. Ann Intern Med. 2016;165:237–244.
22. Wilson IB, Landon BE, Hirschhorn LR, et al. Quality of HIV care provided by nurse practitioners, physician assistants, and physicians. Ann Intern Med. 2005;143:729–736.
23. Gershengorn HB, Wunsch H, Wahab R, et al. Impact of nonphysician staffing on outcomes in a medical ICU. Chest. 2011;139:1347–1353.
24. Skinner H, Skoyles J, Redfearn S, Jutley R, Mitchell I, Richens D. Advanced care nurse practitioners can safely provide sole resident cover for level three patients: Impact on outcomes, cost and work patterns in a cardiac surgery programme. Eur J Cardiothorac Surg. 2013;43:19–22.
25. Scherr K, Wilson DM, Wagner J, Haughian M. Evaluating a new rapid response team: NP-led versus intensivist-led comparisons. AACN Adv Crit Care. 2012;23:32–42.
26. Day LW, Siao D, Inadomi JM, Somsouk M. Non-physician performance of lower and upper endoscopy: A systematic review and meta-analysis. Endoscopy. 2014;46:401–410.
27. Drennan VM, Halter M, Joly L, et al. Physician associates and GPs in primary care: A comparison. Br J Gen Pract. 2015;65:e344–e350.
28. Schmidt ML, Spencer MD, Davidson LE. Patient, provider, and practice characteristics associated with inappropriate antimicrobial prescribing in ambulatory practices. Infect Control Hosp Epidemiol. 2018;39:307–315.
29. Anderson AM, Matsumoto M, Saul MI, Secrest AM, Ferris LK. Accuracy of skin cancer diagnosis by physician assistants compared with dermatologists in a large health care system. JAMA Dermatol. 2018;154:569–573.
30. Brock DM, Nicholson JG, Hooker RS. Physician assistant and nurse practitioner malpractice trends. Med Care Res Rev. 2017;74:613–624.
31. Norcini J, Boulet J, Opalek A, Dauphinee W. Patients of doctors further from medical school graduation have poorer outcomes. Med Educ. 2017;51:480–489.
32. Choudhry NK, Fletcher RH, Soumerai SB. Systematic review: The relationship between clinical experience and quality of health care. Ann Intern Med. 2005;142:260–273.
33. Abramson SB, Jacob D, Rosenfeld M, et al. A 3-year M.D.—Accelerating careers, diminishing debt. N Engl J Med. 2013;369:1085–1087.
34. Ten Cate O. What is a 21st-century doctor? Rethinking the significance of the medical degree. Acad Med. 2014;89:966–969.
35. Ten Cate O. Trusting graduates to enter residency: What does it take? J Grad Med Educ. 2014;6:7–10.
36. Federation of State Medical Boards. Assessing scope of practice in health care delivery: Critical questions in assuring public access and safety. Published 2005. Accessed April 12, 2019.
37. Peterson LE, Fang B, Puffer JC, Bazemore AW. Wide gap between preparation and scope of practice of early career family physicians. J Am Board Fam Med. 2018;31:181–182.
38. Sweigart JR, Aymond D, Burger A, et al. Characterizing hospitalist practice and perceptions of critical care delivery. J Hosp Med. 2018;13:6–12.
39. OHSU School of Medicine. Implementing a four-year family medicine residency. Published April 19, 2016. Accessed April 12, 2019.
40. Andrews JS, Bale JF Jr, Soep JB, et al.; EPAC Study Group. Education in Pediatrics Across the Continuum (EPAC): First steps toward realizing the dream of competency-based education. Acad Med. 2018;93:414–420.
41. Fazio SB, Ledford CH, Aronowitz PB, et al. Competency-based medical education in the internal medicine clerkship: A report from the Alliance for Academic Internal Medicine Undergraduate Medical Education Task Force. Acad Med. 2018;93:421–427.
42. Dewan M, Walia K, Meszaros ZS, Manring J, Satish U. Using meaningful outcomes to differentiate change from innovation in medical education. Acad Psychiatry. 2017;41:100–105.
43. Institute of Medicine. The Future of Nursing: Leading Change, Advancing Health. 2010.Washington, DC: National Academies Press.
44. Dewan M, Norcini J. A purpose-driven fourth year of medical school. Acad Med. 2018;93:581–585.
45. National Resident Matching Program. Results and Data: 2017 Main Residency Match. 2017. Washington, DC: National Resident Matching Program; Accessed April 12, 2019.
46. National Resident Matching Program. Results and Data: 2018 Main Residency Match. 2018. Washington, DC: National Resident Matching Program; Accessed April 12, 2019.
47. Lieb DA. Missouri expands first-in-nation law to target doctor dearth. STAT. May 15, 2017. Accessed April 12, 2019.
48. Dall T, West T, Chakrabarti R, Reynolds R, Iacobucci W; 2018 update: The complexities of physician supply and demand: Projections from 2016 to 2030. Report prepared for the Association of American Medical Colleges by IHS Markit Ltd. Published March 2018. Accessed April 12, 2019.
49. de Nesnera A, Allen DE. Expanding the role of psychiatric mental health nurse practitioners in a state psychiatric system: The New Hampshire experience. Psychiatr Serv. 2016;67:482–484.
50. American Academy of Family Physicians. Primary care for the 21st century: Ensuring a quality, physician-led team for every patient. Accessed April 12, 2019.
Copyright © 2019 by the Association of American Medical Colleges