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Original Research

The roles of primary care PAs and NPs caring for older adults with diabetes

Everett, Christine M., PhD, MPH, PA-C; Thorpe, Carolyn T., PhD, MPH; Palta, Mari, PhD; Carayon, Pascale, PhD; Gilchrist, Valerie J., MD; Smith, Maureen A., MD, PhD, MPH

Author Information
Journal of the American Academy of PAs: April 2014 - Volume 27 - Issue 4 - p 45-49
doi: 10.1097/01.JAA.0000444736.16669.76
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In the United States, primary care practices are investing significant resources to transform into patient-centered medical homes (PCMHs) to improve the quality of care for patients with chronic illnesses such as diabetes.1–5 Patients with diabetes require preventive, acute, and chronic care services.6,7 Consequently, successful treatment of patients with diabetes can be complex, longitudinal, and resource-intensive, requiring care from multiple providers with a range of clinical expertise.8–11 One goal of the PCMH is to use team-based care to address the complex clinical needs of patients with chronic illness.1,2,12 In the current era of primary care physician shortages, a frequently discussed approach to the PCMH is to increase the presence of physician assistants (PAs) and NPs on the primary care team.13–16

To effectively incorporate PAs and NPs into primary care teams, well-defined roles must be implemented.12,17–20 Roles within an organization are defined in relation to other associated positions and according to the functions or tasks performed.21 PA and NP roles are negotiated with collaborating physicians within the constraints of state regulation of medical practices and defined in relation to their collaborating physician.22–24 Overlapping competencies with physicians paired with the context-specific negotiation of PA and NP tasks and functions let PAs and NPs function in a variety of primary care roles.

PAs and NPs perform substitute roles when they provide patients with the same range of services and perform the same functions as a physician—that is, act as a usual provider of care. In contrast, PAs and NPs perform supplemental roles when they complement or extend the services provided by physicians, such as providing chronic disease care to patients within a practice.24 However, little is known about the frequency with which PAs and NPs act in each role category.

Substitute and supplemental PA and NP roles are useful conceptual constructs, but the classifications do not provide sufficient specificity to assess role effectiveness or guide organizations in implementing PA and NP roles.23,25,26 These constructs address patient care tasks only in relation to the function of the collaborating physician and do not specify which patient care services are performed. The substitute/supplement dichotomy also does not incorporate a key domain in negotiating PA and NP roles: patient complexity. Historically, the role of PAs and NPs was to provide care to well and noncomplex patients for preventive care, acute issues, or treatment of stable chronic conditions.22,27 The belief that patients with complex problems and multiple diagnoses are best served by physicians working with a team of healthcare professionals still predominates.28,29 However, this practice may not be universally implemented, as some evidence suggests that PAs and NPs see patients who are just as complex as those seen by physicians.25,30,31

We propose that three factors combine to determine the practice patterns of primary care PAs and NPs and ultimately define the PA and NP role in primary care: the level of PA or NP involvement, patient care services provided, and the complexity of the patients served. Characterizing PA and NP roles by combining these three domains can help healthcare organizations implement PA and NP roles on primary care teams. The objective of this analysis is to characterize the roles of PAs and NPs on individual panels of primary care patients with diabetes by measuring the three domains specified above and to describe the frequency of each role in a large, multispecialty physician group.


Study population The providers and patients in this analysis are associated with one of the 12 largest multispecialty physician groups in the United States, which provides about 1.7 million ambulatory patient visits per year in specialty and community-based primary care clinics. We analyzed the characteristics and primary care visits of Medicare beneficiaries with diabetes on the patient panels of 210 attending physicians, 24 PAs, 28 NPs, and 51 resident physicians in one of 32 internal medicine, family practice, and geriatric primary care clinics. The Minimal Risk Institutional Review Board at the participating university approved this study with a waiver of HIPAA authorization.

Sample and data sources The sample was limited to adult Medicare patients with diabetes identified as being managed by the provider group.32,33 A validated algorithm was used to identify patients with diabetes requiring at least one inpatient or skilled nursing facility claim or more than one carrier claim associated with an ICD-9-CM code of 250.xx, 357.2, 362.0x, or 366.41 (we also added 648.0x).34 Patients were identified as being managed by the provider group by the plurality provider algorithm.32 Patients were required to have Medicare data from 2007 and 2008 for identification of baseline comorbidities in the year before the analysis year.

The Johns Hopkins Adjusted Clinical Groups (ACG) Case-Mix System Version 10 was used as an overall measure of morbidity burden.35,36 Medicare data included demographic information on Medicare beneficiaries enrolled and/or entitled in a given year, as well as inpatient, skilled nursing facility, outpatient, professional services, home health agency, durable medical equipment, and hospice claims. Each claim contains ICD-9-CM diagnosis codes, CPT-4 procedure codes, clinician identifiers, and the date, place, and type of service. Data from the electronic health record (EHR) and Medicare claims/enrollment data were linked using a crosswalk provided by the partner organization. Data for primary care visits in 2008, including date of service, provider performing the service, the clinic, and the ICD-9 diagnosis codes for patients in the sample were obtained from the EHR.

Definition of panels and roles A panel-level dataset was constructed from the data of 2,603 adult Medicare patients with diabetes. Each panel is defined by the usual provider and the patients for whom that provider delivered the plurality or majority of primary care visits in 2008. Patients were first assigned to the primary care clinic that provided the majority of their face-to-face visits within that 1-year period. Within each clinic, patients were assigned to the individual physician, PA, or NP who provided the majority of visits within that clinic in 2008. In the event of a tie at either step, patients were assigned to the clinic/provider with the most recent visit (closest to the end of the year). Finally, patient panels were constructed by grouping patients assigned to the same usual provider of care within a clinic in 2008.

PA and NP role on the panel was defined by combining the three specified domains. A categorical variable representing the level of PA and NP involvement was divided into three categories: none, usual provider, and supplemental provider.

  • “No PA or NP role” was defined as a panel of patients that had physicians as the usual provider of care and had zero visits with a PA or NP.
  • “Usual provider” was defined as a panel of patients for whom PAs and NPs provided the majority of their visits.
  • “Supplemental provider” panels had a physician as the usual provider of care and at least one patient receiving at least one visit from a PA or NP within the calendar year.

A binary variable representing the amount of chronic care delivered by supplemental PAs and NPs to the panel was constructed. This domain was limited to supplemental PAs and NPs because analyses demonstrated that PAs and NPs acting as usual providers provide a broad range of service types (data not shown).

  • “No chronic care” consisted of panels with supplemental PAs and NPs who delivered no chronic care visits to patients on the panel in the calendar year.
  • “At least some chronic care” panels had supplemental PAs and NPs who delivered at least one chronic care visit to a patient on the panel in a calendar year.

A binary variable indicating that PAs and NPs saw complex patients on the panel was created. Panels with PAs and NPs as usual providers or supplemental providers that provided at least one visit to a patient with an ACG risk score of 2.0 or greater were categorized as having a complex patient.

Finally, a variable with seven categories was created combining all three domains:

  • No PA or NP role
  • Usual provider to less complex patients only
  • Usual provider to at least one high complexity patient
  • Supplemental provider to less complex patients providing no chronic care
  • Supplemental provider to less complex patients only providing at least some chronic care
  • Supplemental provider to at least one high complexity patient providing no chronic care
  • Supplemental provider to at least one high complexity patient providing at least some chronic care.


Panel-level analyses used Stata 11.1.37 Descriptive statistics are provided for panel-level characteristics as means and standard deviations across panels of panel size, within panel sex and Medicare buy-in percentages, and panel mean ACG and age. The percent of panels with PAs and NPs in each of the seven potential roles was calculated.


Two-hundred sixty-three panels were identified in the 32 primary care clinics. Family medicine physicians and PAs and NPs were the usual providers for 52% and 6.8% of panels, respectively. Physicians and PAs and NPs in internal medicine and geriatrics were the usual providers for 35% and 6.1% of the panels, respectively. The mean number of patients on a panel was 10. The average of panel mean ages was 70 years. The average of mean ACG was 1.4, indicating that, on average, panels were 40% more costly than the average older adult population (Table 1). On average, the panels were predominantly female (mean percentage female, 57%) and a mean of 23% of patients on the panels were Medicaid recipients.

Provider and panel characteristics of primary care panels of patients with diabetes (n = 263)

All PA and NP roles were observed (Figure 1). PAs and NPs performed no role in 45% of panels. Of the panels with no PA or NP involvement (n = 119), 61% are in clinics with PAs and NPs. The two most frequently performed PA and NP roles involved the delivery of some chronic care as a supplemental provider (supplemental providers delivering at least some chronic care and providing at least one visit to at least one high complexity patient [17%] and supplemental providers delivering at least some chronic care to less complex patients only [13%]). PAs and NPs acted as usual providers of care for 13% of panels, but rarely to panels with high-complexity patients (2% of panels). In clinics with PAs and NPs, PAs and NPs performed a mean of four roles within a clinic (range, two to six). No clinics had PAs and NPs who performed supplemental roles exclusively. Two clinics implemented supplemental roles serving less-complex patients only. One clinic used only supplemental PA and NP roles involving chronic disease management.

PA and NP roles on panels with Medicare patients with diabetes (n = 263)


This study characterizes the roles of PAs and NPs on individual panels of primary care patients with diabetes by using three domains (level of involvement, patient care services provided, and complexity of patients) and describes the frequency of each role in a large multispecialty physician group. PAs and NPs perform a mean of four roles within a clinic and no clinic restricted PA and NP roles to supplemental roles only. Most PA and NP involvement on panels was in supplemental roles, with PAs and NPs acting as usual providers for 13% of panels. The role most often performed on panels by PAs and NPs was no role (45%). Findings suggest that primary care PAs and NPs perform a variety of roles and frequently perform multiple roles within a clinic.

PAs and NPs performed an average of four roles within a clinic, which likely reflects PA and NP role negotiation with each collaborating physician. Although this finding highlights the beneficial flexibility of these professions within primary care settings, the simultaneous performance of multiple roles creates the potential for role ambiguity and confusion. This could result in negative organizational outcomes including PA and NP job stress and turnover, as well as challenges in communication and coordination between providers that may affect patient care decisions.38–40 Additional study is needed to understand the effect of this finding on organizational and patient outcomes.

The predominance of supplemental roles for PAs and NPs reflects one organizational interpretation of team delivery of primary care. The most frequent supplemental roles involve the delivery of chronic care. This suggests that primary care PAs and NPs in this organization were intended to provide a range of primary care services and not simply a subset of services such as acute care. The high frequency of supplemental PA and NP roles could be a function of high ratios of physicians to PAs and NPs. For example, if a PA or NP works with three physicians, the PA or NP has the potential to perform supplemental roles on three panels but only one opportunity to act as a usual provider. However, PAs and NPs make up 17% of the primary care providers but acted as usual provider to only 13% of the panels. Therefore, not all PAs and NPs in the sample acted in usual provider roles, suggesting that the supplemental nature of PA and NP roles is likely intentional.

The relative infrequency of panels with PAs and NPs in usual provider roles suggests that PAs and NPs may not be practicing at the upper limit of their scope of practice in this study population. However, this finding could also be explained by part-time employment or years of PA and NP experience. Additional research evaluating predictors of PA and NP role and the effectiveness and efficiency of each role is warranted. Finally, PAs and NPs frequently perform no role on patient panels (45%), suggesting that creating primary care teams with PAs and NPs would result in a significant system change for this organization.

Limitations The data source for this study is a single physician group. Although the study population comprised patients treated by a relatively large number of providers in more than 30 academic and community-based clinics with unique structures and environments, only one healthcare organization is represented. This is ideal for controlling for variation in regional and organizational characteristics, but the setting may not easily generalize to patients with other chronic illnesses or with other sociodemographic characteristics.

Second, PA and NP supplemental roles for each panel are a composite value of all PAs and NPs serving on a panel. Infrequently, multiple PAs and NPs provided supplemental care to a panel. In these situations, we were unable to determine their individual roles, which may vary. In an era focused on redesigning the structure of primary care to improve care for patients with chronic illness, incorporating PAs and NPs on primary care teams is a common strategy.15,41–43 The results of this study suggest that PAs and NPs perform a wide variety of roles that could potentially be designed to reflect organizational goals and the needs of the patient population. Although this new evidence addressing flexibility should be considered encouraging, conclusions about the appropriateness of one role over another are premature. Effective use of PAs and NPs on primary care teams will remain elusive until the roles of PAs and NPs are defined relative to the full scope of patients served in primary care, and their effect on organizational and patient outcomes, including job turnover, provider satisfaction, and quality of care, is evaluated.


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        physician assistant; nurse practitioner; diabetes; primary care; patient-centered medical home; teams

        © 2014 American Academy of Physician Assistants.