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Systematic Review

Where are we now? Practice-level utilization of nurse practitioners in comparison with state-level regulations

Zwilling, Jana G. MS, APRN, FNP-C (Clinical Assistant Professor, Director, FNP Program)1; Fiandt, Kathryn PhD, APRN, FNP-BC, FAANP, FAAN (Professor, Associate Dean for Transformational Practice and Partnerships)2

Author Information
Journal of the American Association of Nurse Practitioners: June 2020 - Volume 32 - Issue 6 - p 429-437
doi: 10.1097/JXX.0000000000000270



There are presently 248,000 licensed nurse practitioners (NPs) in the United States; 90% of these NPs are certified to practice with primary care populations (AANP, 2018a). These certifications include family (60.6%), adult-geriatric (20.1%), women's health (3.4%), or pediatric (4.6%) (AANP, 2018a). Historically, NPs care for rural and underserved populations. Sixty-six percent of NPs work in communities with populations of less than 250,000, with 35% practicing in communities of less than 50,000 (Chattopadhyay, Zangaro, & White, 2015). A study of the geographic distribution of primary care clinicians demonstrated an average of 5.8 more NPs per 100,000 patient population in rural areas versus urban, whereas there were 24 less physicians per 100,000 patient population in rural versus urban areas (Graves, et al., 2016). According to the American Association of Nurse Practitioners (AANP), “Nurse practitioners assess patients, order and interpret diagnostic tests, make diagnoses, and initiate and manage treatment plans, including prescribing medications” (AANP, 2018c). Nurse practitioners have fully independent practice in 22 states and Washington D.C. presently, with legislative efforts active in many other states (AANP, 2018b).

The AANP categorizes states into three groups by practice environment: full practice, reduced practice, and restricted practice (AANP, 2017). A full practice environment involves state practice and licensure laws under the exclusive authority of the state board of nursing and does not require collaboration or supervision by another health care discipline. A reduced practice environment includes the reduction of the NPs capacity to participate in at least one component of their practice, including the constraint of a collaborative agreement with another health care discipline, such as a physician (AANP, 2017). Finally, restricted practice environments necessitate “supervision, delegation, or team-management by an outside health discipline” (AANP, 2017).

Full practice authority in all states is optimal for high-quality, cost-effective health care that increases access for the patient. In 2010, the National Academy of Medicine (formerly the Institute of Medicine) and the National Council of State Boards of Nursing recommended the removal of barriers to full scope of practice to pursue the “Triple Aim” as outlined by the Institute for Healthcare Improvement (IHI, 2018). The “Triple Aim” appears to have been tailored to NP practice with the focus on improvement in patient experience and population health while reducing per capita health care costs. Studies have shown that NPs provide high-quality patient outcomes, rank high in patient satisfaction, and do this for less cost than other provider types (Horrocks, Anderson, & Salisbury, 2002; Zismer, Christianson, Marr, & Cummings, 2015).

The conceptual framework used for this review was devised with concepts from the Diffusion of Innovation Theory, Implementation Theory, and the Theory of Street-Level Bureaucracy (Lipsky, 2010; Rogers, 2003; May, 2013). The framework outlines the process of an innovation being adopted at the regulatory level and implemented at the local level as well as the process of various translations through this course, see figure 1. The specific area of focus for this review is the local translation and the components of practice utilization that are affected. Therefore, the objective of this integrative review is to determine the state of the science regarding practice-level utilization (PLU) of NP with specific emphasis on potential variations in PLU in comparison to state-level regulations (SLRs).

Figure 1
Figure 1:
Conceptual framework. Local translation of innovation, guided by the Diffusion of Innovation Theory, Implementation Theory, and the Theory of Street-Level Bureaucracy (Lipsky, 2010 ; May, 2013 ; Rogers, 2003).


For this study, we reviewed articles indexed in databases of peer-reviewed literature, following the process for integrative review proposed by Whittemore and Knafl (2005). A systematic search was conducted of the CINAHL, PubMed, and Scopus databases for English language articles reporting original research on NP scope of practice and PLU on samples within the United States. The keywords nurse practitioner, independent practice, full scope of practice, utilization, restriction, role, practice pattern, limitation, credentialing, and privileges were used to retrieve articles published from January 1989 to December 2018. The beginning date was chosen because the Omnibus Reconciliation Act of 1989 initiated limited reimbursement for NPs; therefore, reports on independent practice for NPs before this year were unlikely.

From the retrieved articles, we then identified studies involving NP practice, role, and/or regulation that also addressed PLU. Reviews, expert opinions, and commentaries were excluded. Additional criteria for inclusion were original research and reported NP data separately versus in aggregate with other provider types. Articles were excluded if they only studied students or educational programs, focused on a single clinical intervention, addressed only state- or national-level policies, reported only provider perceptions, or population was limited to one facility. Data were extracted and collected through an evidence table (Table 1, Supplemental Digital Content 1, available at using the Joanna Briggs Institute Critical Appraisal Tool template (Munn, Moola, Lisy, Riitano, & Tufanaru, 2015).

Our initial search yielded 1,967 articles, which were reduced to 419 after applying preliminary search criteria of English language, inclusive dates of January 1989 through December 2018, and a sample based in the United States. After additional articles were identified through hand search of references and duplicates were removed, 349 articles remained. Title and abstract review excluded 263 articles. Full text of 86 articles were read, 67 were excluded, leaving 19 articles in the final review. Figure 2 provides a PRISMA flow diagram illustrating specifics of the search strategy with inclusion and exclusion criteria (Moher, Liberati, Tetzlaff, & Altmann, 2009).

Figure 2
Figure 2:
Literature search flow diagram.


Study characteristics

Although our search criteria included studies between 1989 and 2018, the final articles included only two studies older than 2010 (Kinney, Hawkins, & Hudmon, 1997; Larsson & Zulkowski, 2002). All studies used a cross-sectional descriptive design, three using secondary data analysis of large national databases (Kleinpell, Cook, & Padden, 2018; Pittman, Leach, Everett, Han, & Mcelroy, 2018; Spetz, Skillman, & Andrilla, 2017), and the remaining studies used a survey format. There were six different sample types used in the literature including NPs only, NPs and med directors (MDs), NPs and administrators, APRNs, administrators only, and hospital organizations. Studies in which NPs were included in the sample were further delineated to illustrate types of NPs used in those samples. Nine studies sampled primary care NPs (PCNPs) (Buerhaus, DesRoches, Dittus, & Donelan, 2015; Donelan, DesRoches, Dittus, & Buerhaus, 2013; Poghosyan, Boyd, & Knudson, 2014; Poghosyan & Liu, 2016; Poghosyan, Liu, & Norful, 2017a; Poghosyan, et al., 2015; Poghosyan, Norful, & Martsolf, 2017; Poghosyan & Aiken, 2015; Rudner & Kung, 2017), one study used samples of all NP certification types (Spetz et al., 2017), and one study each sampled acute care NPs (ACNPs) (Kleinpell et al., 2018) and neonatal NPs (NNPs) (Freed, Dunham, Lamarand, Loveland-Cherry, & Martin, 2010). Over half of the articles reported on single states; geographical focus of the studies is visualized in figure 2. Sample sizes of the studies including NPs ranged from 60 to 13,000 NPs. Studies including administrators had sample sizes of 60–407, MD samples were n = 505, hospital or organization samples ranged from 25 to 213, and APRN sample was n = 259.


The scientific rigor was evaluated using the Joanna Briggs Institute Critical Appraisal tools: Checklist for Prevalence studies (Munn, et al., 2015). Rigor components included sampling, setting, instruments, methods, statistical analysis, and response rates. Seven of the 19 studies used nationwide samples (Kinney, et al., 1997; Kleinpell et al., 2018; Spetz et al., 2017; Buerhaus et al., 2015; Donelan et al., 2013; Freed, Dunham, Lamarand, Loveland-Cherry, & Martyn, 2010; Gigle, Dietrich, Buerhaus, & Minnick, 2018), one used 34 states (Pittman et al., 2018), three used between two and eight states (Krien, 1997; Poghosyan & Aiken, 2015; Poghosyan et al., 2015), and the remaining studies had samples from only one state. Four studies employed a random stratified sampling strategy (Buerhaus et al., 2015; Donelan et al., 2013; Freed et al., 2010; Kleinpell et al., 2018), and two used simple random sampling (Spetz et al., 2017; Peterson, Keller, Way, & Borges, 2015). Four studies used purposive sampling of an entire population (Britell, 2010; Gigli, Dietrich, Buerhaus, & Minnick, 2018; Krien, 1997; Larsson & Zulkowski, 2002) and nine used convenience samples. Fourteen of the 19 articles used a survey method of data collection, three utilized a secondary data analysis, and the remaining two used a mixture of secondary data collection and survey method. The studies using surveys reported validity and reliability measures, all scored above 0.8 Cronbach alpha. The average response rate for those studies using either a survey method or performing a secondary analysis on survey findings was 39%. The range of response rates was 9.9%–93%. Eight of the 19 studies had response rates over 50%. Nursing surveys have a typical response rate of about 39%; 12 of the studies had sample sizes at or above this percentage (Aiken, Clarke, Sloane, Sochaslski, & Silber, 2002; Smith, 2008). The most common limitations in the group of studies was nonresponse bias and self-report on a survey.

State regulations

Thirteen articles either did not address or explicitly define the practice authority in the state or states being studied. Of the articles defining state practice authority, only three used formal reporting methods (Kinney et al., 1997; Kleinpell et al., 2018; Pittman et al., 2018). One used the AANP three-tiered model, and the other two used the grading system from the Pearson Report (Bureau of Primary Healthcare, 2002; Kleinpell et al., 2018; Pearson, 2014; Pittman et al., 2018). The AANP model divides states into full, reduced, and restricted practice states as described previously (Spetz et al., 2017). The Pearson Report provides a comprehensive biennial report of each state and multiple components of practice authority, such as regulatory bodies, prescriptive authority, and practice supervision (Buerhaus et al., 2015). These three articles were also the only articles specifically defining independent practice or full practice authority.

Seven of the studies included nationwide samples (Donelan et al., 2013; Kinney et al., 1997; Kleinpell et al., 2018; Pittman et al., 2018; Poghosyan et al., 2014, 2017; Poghosyan & Liu, 2016), and one study included samples from 34 states (Pittman et al., 2018) and therefore likely included all tiers of practice regulation as there were 22 of 50 states with full practice authority at the time of this review. However, the samples within those seven studies were not stratified by tier, and determination could not be made as to the power of the samples from the individual tiers. Eight studies examined samples from only one state (Freed et al., 2018; Gigli et al., 2018; Munn et al., 2015; Peterson et al., 2015; Poghosyan & Aiken, 2015; Poghosyan et al., 2015; Poghosyan et al., 2017; Rudner & Kung, 2017), three from full practice authority states, two from reduced practice states, and three from restricted practice states. Two studies looked at two tiers, both using reduced and restricted environments (Krien, 1997; Peterson et al., 2015). A caveat to the state samples is that most studies did not explicitly include information on the state practice authority; however, we deduced the level of authority by using the AANP three-tiered model (Spetz et al., 2017). One study had an eight-state sample; however, the study was conducted in 1997 before any readily accessible documentation of NP practice authority regulation changes (Krien, 1997).

Practice-level utilization

As visually outlined in figure 1, the local translation theory surmises that practice utilization consists of four components: level of supervision, prescriptive authority, practice privilege, and billing privileges. Practice privileges includes settings in which NPs are allowed to practice such as inpatient or outpatient, and what services they are allowed to provide. Billing practices refers to whether the institution allows NPs to bill under their own National Provider Identifier (NPI), bill as “incident to” a physician, or under an organizational NPI. Prescriptive authority refers to whether NPs are allowed to prescribe independently without physician co-signature, and the classes or schedules of medications they are allowed to prescribe. Finally, supervision is whether the institution requires supervision or collaboration with another health care provider such as a physician.

We found nine components of PLU outlined in the literature, shown in figure 3. Of these nine, site of employment and supervision were the most frequently examined. We defined site of employment as practice site, such as outpatient clinic or hospital, as well as location identified as rural, suburban, or urban. Four studies did not report a site of employment, seven studies reported on practice site only, and the remaining six reported on practice site and geographic location. Figure 4 provides a visual of the geographical locations represented in the literature.

Figure 3
Figure 3:
Components of practice utilization investigated; bar graph demonstrating number of studies investigating each component of utilization.
Figure 4
Figure 4:
Number of NPs studied by practice location; pie chart demonstrating number and percentage of NPs from rural, suburban, and urban locations included in the studies within the review. NP = nurse practitioner.

Level of supervision

Nine studies included a report of the level of supervision of the NP by a physician (n = 2,800). There was not a true consensus on the definition of supervision throughout the studies. Supervision was typically based on self-report of a collaborative or supervisory practice or a “multidisciplinary” practice versus reference to state regulation or formal written agreement. On average 34.75% of NPs studied reported no supervision, 56.6% reported a collaborative agreement was in use, and 48.5% reported direct supervision by a physician. Two studies examining samples in single states with a large rural population reported 64–75% of NPs in rural locations practiced without supervision (Peterson et al., 2015; Britell, 2010). The two states included were Washington and New Mexico, both with full practice authority. One nationwide study comparing rural versus urban practicing NPs reported NPs practicing in rural areas were more likely to be in states without a supervision requirement (Spetz et al., 2017). The study found less NPs per capita in rural areas, but an increased proportion of PCNPs. Nurse practitioners in rural areas were also found to agree when asked if their skills are fully used and if they practice to the full extent of their state's legal practice authority (Spetz et al., 2017).

Studies examining samples of specialty NPs such as acute or NNPs had a much higher rate of supervision. In a nationwide study of NNPs, only 2% reported practicing without supervision (Poghosyan et al., 2014). In fact, the study reported that very few differences existed in practice utilization of NNPs between independent and nonindependent states (Poghosyan et al., 2014). Acute care NPs are becoming more prevalent in the United States with approximately 10% of all practicing NPs having this certification compared with 4.3% in 2004 (Kleinpell et al., 2018; Kleinpell & Goolsby, 2006). A nationwide study in 2018 reported that 87% of ACNPs have either collaborative or supervised practices regardless of state regulation (Kleinpell et al., 2018).

Another aspect of supervision level is whether NPs have their own panel of patients not requiring intermittent visits with a physician or not shared with a physician. Six studies included this measurement in their examinations (Larsson & Zulkowski, 2002; Poghosyan & Aiken, 2015; Poghosyan et al., 2014; Poghosyan et al., 2017; Poghosyan et al., 2017b; Poghosyan & Liu, 2016; Spetz et al., 2017). Overall, 52% of NPs sampled in these studies reported having their own panel; all were PCNPs. One study showed 50% of NPs without their own panel worked in physician offices, whereas overall 45% had their own panels; this study was conducted in one state with restricted practice (Peterson et al, 2015). Another study reported that nearly 80% of NPs in isolated rural areas had their own panels, whereas only 55% NPs in urban areas had the same (Poghosyan et al., 2017a). No studies addressed whether NPs in specialty practices had their own patient panel.

Prescriptive authority

Authority to provide prescriptions is a key component of independent practice. In fact, there are no states with independent prescriptive authority that do not also have full practice authority (AANP, 2017). There are varying levels of prescriptive authority even among states with the same level of practice authority. Only three studies specifically addressed prescribing without physician oversight (Kinney et al., 1997; Krien, 1997; Larsson & Zulkowski, 2002). Two of these studies did not include the prescriptive authority as a specific question on their survey but relied on the AANP scope within the states surveyed to relay that the NPs had the authority (Kinney et al., 1997; Larsson & Zulkowski, 2002). The remaining study was nationwide and reported 61% of NPs having prescriptive authority but did not stipulate the state scope of practice tier(s) correlating to those with the authority (Krien, 1997).

Practice privileges

Privileging involves the authorization of a health care professional to perform each service they will provide at the institution of employment. This is not to be confused with credentialing, which is simply verifying qualifications of a health care professional such as licensing and certifications (Bureau of Primary Healthcare, 2002). Hospital and long-term care admitting were the only structured activities examined as privileges within the literature. There were, however, other factors included within investigations that can be discerned as privileges. To formulate synthesis for this review, we included the following as privileges: type of patients seen, procedures performed, type of appointments, services provided, and admitting. Eleven studies explicitly identified one or more privileges as part of their examination of the NP practice utilization. Hospital and/or long-term care admitting was reported in five studies (Buerhaus et al., 2015; Kinney et al., 1997; Kleinpell et al., 2018; Krien, 1997; Larsson & Zulkowski, 2002). Two studies reported specific procedures performed by NPs in practice (Kinney et al., 1997; Pittman et al., 2018). One study each reported on type of patients, type of appointments, and services provided (Britell, 2010; Kinney et al., 1997; Larsson & Zulkowski, 2002). Of the studies addressing admitting privileges, an average of 31.66% of NPs had hospital and 6% had long-term care admitting within their organizational scope of practice. Three of the five studies reporting on admitting privileges had PCNP samples, and two examined ACNPs or specialty practice. On average, 13.5% of NPs in primary care held admitting privileges. It was found, again, that NPs practicing in rural or isolated rural areas had greater levels of privileging authority, including more with hospital and long-term care privileges (Spetz et al., 2017).

Billing practices

Billing practices were reported in four studies as part of practice utilization components (Buerhaus et al., 2015; Gigli et al., 2018; Kinney et al., 1997; Spetz et al., 2017). Billing practices were confined to whether NPs billed under their own NPI number. Based on the four studies that addressed billing, roughly 30% of NPs bill under their own NPI number. Nurse practitioners practicing in rural areas were also more likely to bill under their own NPI. In practices including a physician, 31% of PCNPs reported billing to their own NPI, whereas 56% billed to their own NPI when not in a practice including a physician (Buerhaus et al., 2015). In specialty care, more NPs reported billing either as incident to the physician or under the umbrella organization NPI. In fact, only 25% of NPs in the pediatric intensive care specialty and 8% of oncology NPs reported billing under their own name or NPI number (Gigli et al., 2018; Kinney et al, 1997).

An additional and quite important component of NP practice utilization is the ability to have a voice within the institution. Only two studies addressed whether NPs were allowed inclusion in medical staff meetings or to have hospital board voting privileges (Kleinpell et al., 2018; Krien, 1997). Again, NPs practicing in rural areas were more satisfied with their voice within their organizations (Krien, 1997).


The “Triple Aim” focuses on improving health, enhancing the patient experience, and reducing cost (IHI, 2018). Nurse practitioners are providing all three components in care throughout the country. The literature has demonstrated that NPs improve access by working in rural and underserved areas, provide cost effective care, and have high patient satisfaction ratings. However, this fulfillment of the “Triple Aim” has yet to reach full potential. Almost half of the US states have full practice authority with the remaining states having reduced or restricted practice for NPs (AANP, 2017). Even among and within states with full practice authority, there are variations in how NPs are utilized in health care organizations. This review was undertaken in attempt to understand how NPs are utilized and if the scientific literature had a definite answer. This research is critical, because access to quality health care is a significant issue throughout the United States. If NPs are continuing to practice in environments that restrict their practice, regardless of state regulations, patients will continue to be negatively affected and the “Triple Aim” will not be met.

Our overall approach to this study was to view the literature through the lens of “local translation”. Studies that examined how NPs are utilized at the local or organizational level were specifically included. The novelty of this approach is the aspect of tying organizational level utilization to SLR. The most significant finding in this review was the lack of standardized evidence on the PLU of NPs, specifically in comparison to the regulations of the practice state. No studies focused on the type of NP certification, practice specialty, utilization, and compared these three components to the state practice regulation. All of these components must be included to complete the picture of utilization. Other noteworthy findings were the heavy sampling of PCNPs and apparent difference in utilization between rural and urban NPs.

Type of NP certification, practice specialty, and utilization do not always align. This makes determination of utilization and workforce analysis even more difficult. For example, the utilization of a Family certified NP working in a family medicine clinic will be significantly different than a Pediatric Acute Care certified NP working in an inpatient setting, as it should be. Although the utilization differences in this example are rather obvious, the less apparent is the difference in utilization of a Family certified NP working in a primary care clinic in a rural area of a full practice authority state as compared with a Family certified NP working in a primary care clinic in an urban area of the same state. Unless researchers begin to collect data on certification, specialty area of practice, and utilization, the true deployment of NPs is difficult to discern.

Another intriguing finding was the heavy sampling of “primary care” NPs. This was not defined by certification but by the practice type. This can be problematic as a standard definition of primary care is not prevalent across disciplines or even in different geographical areas. For example, in a rural Critical Access Hospital, primary care clinicians serve in outpatient clinics, inpatient hospital settings, Emergency Departments, and with on-call services out of necessity for the patients and community (Rural Health Information Hub, 2018). In urban areas with more health care provider density, primary care may only include the outpatient clinic setting. Despite the focus on NPs in primary care practices, there is still a lack of evidence on utilization as compared with state regulation. Additionally, although 90% of NPs are trained and certified in a primary care area (AANP, 2018b), many are branching off into specialty areas. In fact, specialty practices are becoming more common among NPs, especially in urban areas, although there are few actual specialty certifications specifically geared for NPs (AANP, 2018a). Nurse practitioners are certified by the population they are trained to serve, not by practice type (NONPF, 2013). The exceptions to this are acute care, which is a subset of the adult-geriatric or pediatric population certification, and emergency, which is an additional optional certification for FNP and adult-geriatric PCNPs working in emergency care (NONPF, 2013). There are limited investigations on utilization of NPs in primary care and no investigations on how PCNPs are being utilized within specialties.

Of specific interest is the geographical variation in utilization of NPs. Only 21% of the NPs included in the samples were identified as practicing in rural areas. There was consistency in the higher level of utilization and lower level of supervision required in rural areas as compared with urban. Practice organizations with physicians on staff were also more likely to require supervision and less extensive privileges for NPs. Rural organizations, such as Critical Access Hospital, tend to have fewer physicians on staff, some have no collocated physicians, and therefore frequently do not require supervision.

Limitations identified in the literature were primarily related to geographical location and practice site. Urban NPs were heavily sampled throughout the literature. As noted in the review, urban NPs have been found to have less privileges and more supervision when compared with NPs practicing in rural areas. Granted, NPs are geographically distributed unevenly along with the general population. However, the heavy urban sampling may not provide an adequate picture of utilization. Another concern is the lack of identification of NP-owned or private practice NPs throughout the studies. The utilization of an NP in his or her own practice may be significantly different than an NP withheld to organizational restrictions. The final limitation noted was that almost half of the studies were conducted on a single state. Although this is important to policy makers within that state and to others attempting to conduct workforce research within their own states, it does not provide generalizability.

Federal and state legislative efforts continue to move forward with increasing practice authority for NPs. Although it is necessary to continue this pursuit, it is also important to understand how NPs are being used within health care systems. Nurse practitioners have worked very hard to gain full practice authority in almost half of the United States to provide increased access, reduced costs, and improved patient experiences. Unfortunately, we do not yet understand if all our efforts have made the impact we so avidly sought. Based on the paucity of all-encompassing evidence of local level utilization included in the current literature, there is a potential for local institutional constraints on NP practice of which we may be unaware. Workforce analysis and planning are potentially inadequate if the true utilization of the NP is unknown. Optimization of current assets is the first step in adequate health care workforce; once that is accomplished, then supply and demand can be more adequately forecasted. State and Federal Legislators have the health of the population to consider and therefore need as much information as possible, including local utilization, for decision-making regarding adequate resources for health care.

Further investigation is needed to identify disconnects between SLRs on NP practice authority and PLU. Specifically, utilization stratified by practice authority and including variables of geographical location, certification type, and practice type should be explored. Structures of health care organizations along with local bureaucracy and work environments of institutions restricting NP scope of practice despite full practice authority regulations at the state level should be a focus as well.


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    Full scope of practice; nurse practitioner; restriction; role; utilization

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