The Role of Restrictive Scope-of-Practice Regulations on delivery of Nurse Practitioner-delivered Home-Based Primary Care

Abstract

Background:

Nurse practitioners (NPs) are the largest group of providers delivering home-based primary care (HBPC) in the U.S. We examined the association of scope-of-practice regulations and NP-HBPC rates.

Methods:

Using Centers for Medicare and Medicaid Services Provider Utilization and Payment Data Public Use File (PUF) for 2019, we conducted a state-level analysis to examine the impact of scope-of-practice regulations on utilization of NP-HBPC. Healthcare Common Procedure Coding System (HCPCS) codes were used to identify the HBPC visits in private residences (99341–99345, 99347–99350) and domiciliary settings (99324–99328, 99334–99337). We used linear regression to compare NP-HBPC utilization rates between states of either restricted or reduced scope-of-practice laws to states with full scope-of-practice, adjusting for number of NP-HBPC providers, state ranking of total assisted living, the proportion of FFS Medicare beneficiaries and neighborhood-level socio-economic status and race and ethnicity.

Results:

Nearly half of NPs providing HBPC (46%; n=7151) were in states with restricted scope of practice regulations. Compared to states with full scope-of-practice, states with restricted or reduced scope-of-practice had higher adjusted rates of NP- HBPC per 1,000 FFS Medicare beneficiaries. The average level of utilization rate of NP- HBPC was 89.9, 63, and 49.1 visits, per 1000 FFS Medicare beneficiaries in states with restricted, reduced, and full- scope-of-practice laws, respectively. The rate of NP-HBPC visits were higher in states with restricted (Beta coefficient=0.92; 95%CI 0.13–1.72; p=0.023) and reduced scope-of-practice laws (Beta coefficient=0.91; 95%CI 0.03–1.79; p=0.043) compared to states with full scope-of-practice laws.

Conclusion:

Restricted state NP scope-of-practice regulations were associated with higher rates of fee-for-service Medicare NP-HBPC care delivery compared with full or reduced scope-of-practice. Understanding underlying mechanisms of how scope-of-practice affects NP-HBPC delivery could help to develop scope-of-practice regulations that improve access to HBPC for the underserved homebound population.

Introduction

Nurse practitioners (NPs), the fastest growing workforce of primary care providers in the U.S,^1,2 are an integral component of the home-based primary care (HBPC) workforce.^3–5 Growth in labor supply of NPs delivering HBPC accompany a concurrent increase in the homebound population,^6,7primary care physician shortages,^8,9 and a national shift towards community-based care.¹⁰ In a study using national claims data from 2012 to 2013, among physicians, NPs, and physician assistants who provided HBPC, almost 3,300 NPs made over 1.1 million home visits to Medicare fee-for-service beneficiaries.⁵ Between 2012 and 2016 the number of NPs providing HBPC nearly doubled in the U.S.¹¹ More recent data from 2017 shows that 5899 NPs made 2.1 million visits compared to 1.9 million visits by 5704 physicians.¹²

Despite the expanding utilization of NP - HBPC, there are substantial barriers to NP delivery of HBPC. A commonly cited barrier is that restricted scope-of-practice are thought to reduce availability of NP HBPC.^13–16 State scope-of-practice regulations stipulate the extent to which an NP can practice without physician oversight and vary by state. In some states, scope-of- practice regulations impose significant limitations on the services that a NP may provide. States with restricted scope-of- practice regulations require NPs to have “career - long supervision” by a physician while full scope-of-practice states allow NPs to practice without physician supervision.¹⁷ Such supervision requires physicians to conduct chart review of patients assigned to NPs, on-going communication with NPs about patient care, and supervised controlled substance prescribing.

Most evidence about the impact of scope-of-practice regulations is focused on NP care in ambulatory or inpatient settings, and shows that full scope-of-practice policies increase access to NP care particularly for low income adults with greater shortage of primary care clinicians, and rural residents^18–22 These findings may not be generalizable to care provided in a patient’s home environment. Access to HBPC is particularly important for homebound older adults because of its associations with fewer hospitalizations/emergency room visits,^4,23 higher rates of advance care planning,²⁴ and coordinated care required to enable homebound adults remain in their own homes and out of nursing home settings.²⁵ With the NP workforce expected to nearly double in upcoming years,^2,26 and states progressively expanding NP scope-of-practice regulations to allow NPs to care for patients without physician oversight,²⁷ the growing numbers of NPs may be deployed to meet this growing demand for HBPC. Yet, little research has examined the impact of scope-of-practice regulations on the delivery of HBPC.

Only 12% of homebound older adults currently access HBPC, which may be in part due to lack of HBPC workforce.⁷ Strategies to ensure adequate NP workforce to meet the demands for HBPC require an understanding of state-level barriers that may impact access to NP- HBPC. To understand the relationship between states’ scope-of-practice regulations and the utilization of NP-HBPC, we analyzed variation in state scope-of-practice regulations for nurse practitioners in all 50 states. Using 2017 provider-level data, one study has shown that in states with restricted scope-of-practice regulations, compared to NPs, physicians and physician assistants had higher odds of providing HBPC.¹² In the present study, we conducted an updated state-level analysis to examine the impact of NP scope-of-practice regulations on delivery of NP-HBPC and describe utilization of NP-HBPC by race, ethnicity, and socioeconomic conditions. We hypothesized that full scope-of-practice regulations would be associated with greater utilization of NP-HBPC.

Methods

Data Source and Sample

We used CMS Provider Utilization and Payment Data Public Use File (Physician and Other Supplier PUF) for the calendar year 2019. The provider PUF includes data on utilization, payment, and submitted charges for Medicare beneficiaries enrolled in the fee-for-service program organized by National Provider Identifier (NPI) and Healthcare Common Procedure Coding System (HCPCS) code. These data include physician claims activities such as utilization, payment, and place of service but not information about specific patients, as the PUF only reports on provider billings where greater than 11 beneficiaries per HCPCS were served.

Providers were identified by using the provider type variable included in the Physician and Other Supplier PUF and assigned to the State where their NPI was registered. Only NPs were included in the analysis. HCPCS codes were used to identify the HBPC visits to private residences (99341–99345, 99347–99350) and domiciliary settings (99324–99328, 99334–99337).²²

Measures

Outcome variable. The outcome of interest was NP- HBPC utilization, calculated by dividing the sum of all NP-HBPC visits for individual states by the state-level Medicare FFS population size. The state-level count of FFS population was obtained from the Geographic Variation PUF.²⁸

Covariates. The main independent variable was State designation of NP scope-of-practice regulation, as classified according to the 2019 scope-of-practice regulation defined by the American Academy of Nurse Practitioners (AANP).²⁹ This 3-level classification categorizes states as: (1) “full practice” whereby NPs have full and independent practice and prescriptive authority without physician supervision; (2) “reduced practice” which requires NPs to have collaborative agreement with physicians for at least one element of NP practice; and (3) “restricted practice,” where by career-long supervision, delegation, or team management by a physician is required in order for an NP to practice or prescribe.²⁹

State-level indicators of socioeconomic status were grouped by state-level median household income obtained from the 2015 –19 American Community Survey (ACS): (<47999; $48,000-$60,999; $61,000-$81,999; and $82,000 or greater).²⁷ ACS data were used to identify the proportion of patient population who were black, Hispanic, as well as the proportion of those living below the poverty line who were 65 years or older. A state-level indicator of assisted living options and residential care capacity was included using the 2019 long-term services and supports (LTSS) State Scorecard rankings of assisted living and residential care units per 1000 older adults served.³⁰

Statistical analysis

Summary statistics were calculated of the number of all providers who had HBPC visits, NPs who provided HBPC visits, NP-HBPC utilization rate, as well as covariates using mean (standard deviation) and median for continuous variables and frequency and proportion for categorical variables. Summary statistics stratified by scope-of-practice categories(full/reduced/restricted) were also calculated. Linear regression was used to compare NP-HBPC utilization rate between states of either restricted or reduced scope-of-practice with full scope-of-practice states, with and without adjusting for the aforementioned state-level covariates. HBPC visits were log transformed to account for its skewed distribution. The analysis was conducted using SAS (v9.4) and R (V4.0.2).

Results

Table 1 depicts characteristics of NP-HBPC utilization rates by state scope-of-practice status. NPs represented 50% of the total HBPC providers (n=15,418). Twenty-three (45%) states were with full scope-of-practice, 16 (31%) were states with reduced scope-of-practice, and the remaining 12 (24%) were states with restricted scope-of-practice (Figure 1). Nearly half of HBPC-NPs (46%; n=7151) were located in restricted practice states, while the lowest number of NP-HBPC providers were located in states with full scope-of-practice regulations(18.9%; n=1467).

Table 1.

Summary characteristics of NP- HBPC utilization rates by scope-of-practice status.

	All	Full scope-of-practice (23; 45%)	Reduced scope-of-practice (16; 31%)	Restricted scope-of-practice (12; 24%)
	Mean (SD)	Mean (SD)	Mean (SD)	Mean (SD)
Overall HBPC	63 (49.2)	49.1 (50.7)	63 (38.2)	89.9 (51.6)
HBPC in private residences	22.5 (25.8)	15.4 (28.9)	27.4 (24.2)	29.5 (19.2)
HBPC in domiciliary settings	40.5 (33.9)	33.6 (33.7)	35.6 (23.6)	60.4 (40.5)
a Overall HBPC	40.4 (3.3)	24.5 (4.3)	51.0 (2.0)	77.3 (1.8)
a HBPC in private residences	10.6 (5.0)	4.6 (6.9)	18.4 (2.7)	25.0 (1.8)
a HBPC in domiciliary settings	24.1 (4.3)	15.2 (6.8)	27.2 (2.3)	49.1 (2.0)
b FFS population in 1000	648 (593.9)	291.9 (221.4)	718 (473.9)	1237 (740.6)
c LTSS Scorecard rankings of assisted living and residential care units per 1000 older adults	24.4 (14.1)	18 (14; 13)	30.5 (14.7)	28.5 (7.8)
d State-level %Black population	11.3 (10.7)	6.6 (10.6; 3.3)	14.7 (10.3)	15.8 (7.9)
d State-level %Hispanic population	11.9 (10.3)	12.6 (11.1; 10.5)	8.8 (5.9)	14.6 (12.8)
State-level %population living below the poverty line who were 65+ years old	1.4 (0.3)	1.3 (0.3; 1.3)	1.5 (0.4)	1.5 (0.2)
d State-level median household income level	N (%)	N (%)	N (%)	N (%)
≤ $47999	3 (6%)	0 (0%)	3 (19%)	0 (0%)
$48,000 – $60,999	22 (43%)	8 (35%)	6 (38%)	8 (67%)
$61,000 – $81,999	23 (45%)	13 (57%)	6 (38%)	4 (33%)
≥ $82,000	3 (6%)	2 (9%)	1 (6%)	0 (0%)

Note: Data in HBPC visits delivered by nurse practitioners were based on 2019 provider PUF, https://www.cms.gov/Research-Statistics-Data-and-Systems/Statistics-Trends-and-Reports/Medicare-Provider-Charge-Data/Physician-and-Other-Supplier;

^a, geometric mean and the equivalent SD based on the natural log transformed data;

^b, based on state-level enrollment PUF Medicare Geographic Variation - by National, State & County. Accessed June 28, 2021, https://www.cms.gov/Research-Statistics-Data-and-Systems/Statistics-Trends-and-Reports/Medicare-Geographic-Variation/GV_PUF;

^c, based on 20020 data from the Long-Term Services & Supports State Scorecard. Accessed November 9, 2021, http://www.longtermscorecard.org/;

^d, based on 2015–2019 ACS data;

State-level scope-of-practice status and state-level NP- HBPC utilization rate.

Note: The increasing color darkness of HBPC visits corresponds to the 10^th, 25^th, 50^th, 75^th, 90^th, and 95^th percentiles of the state-level HBPC rate). NP=nurse practitioner; HBPC=home based primary care; FFS pop=fee for service population

Overall, the average number of NP-HBPC was greater in states with restricted scope-of-practice laws (mean=89.9 [SD 51.6]), compared to reduced (63 [38.2]) or full (49.1[50.7]) scope-of-practice laws. States with restrictive scope-of-practice regulations had the highest rates of minoritized populations. For example, states with reduced (14.7%) and restrictive (15.8%) scope-of-practice regulation had a greater proportion of Black NP- HBPC compared to full practice states (6.6%). In addition, states with restrictive scope-of-practice regulations served the highest proportion of the Hispanic population (14.6%). Median income was significantly higher in full scope-of-practice states. The more restricted the state scope-of-practice regulation in a state, the greater the socioeconomic disadvantage. Sixty-six per cent of states with median income level $61,000 or above had full scope-of-practice laws, compared to 44% in states with reduced scope-of-practice laws and 33% in states with restricted scope-of-practice laws.

In both crude and adjusted models, the differences by scope-of-practice category were significant (Table 2). NP- HBPC visits rate was higher in restricted (Beta coefficient=0.92; 95%CI (0.13–1.72), p=0.023) and reduced (Beta coefficient=0.91; 95%CI (0.03–1.79), p=0.043) scope-of-practice states than that in the full scope-of-practice states, after adjusting for relevant covariates (Table 2).

Table 2.

Results from the linear regression. Compared to full-scope-of-practice states, states with restricted or reduced scope-of-practice had significantly higher NP-led HBPC visits per 1,000 FFS Medicare beneficiaries.

	Crude model		Adjusted model
	Beta coefficient (95% CI)	p-value	Beta coefficient (95% CI)	p-value
Full- scope-of-practice states	Reference		Reference
Reduced scope-of-practice states	0.74 (0.01–1.46)	0.046	0.92 (0.13–1.72)	0.023
Restricted- scope-of-practice states	1.15 (0.36–1.94)	0.005	0.91 (0.03–1.79)	0.043

Note: The adjusted model controlled for the following state-level covariates: median household income, proportion of population who were Black, Hispanic, and the proportion of those living below the poverty line who were 65 years or older. The outcome of the model was the natural-log transformed HBPC utilization rate (visits per 1000 FFS Medicare beneficiaries). In the log scale, the beta coefficient is the difference in the expected geometric means of the log of HBPC rates between the full-scope- of-practice and reduced- or restricted-scope-of-practice states. An example of interpreting the beta coefficient in the original scale is to exponentiate the coefficient and subtract one. For example, exp(0.91) – 1 =1.46, which can be interpreted as switching from full-scope- of- practice states to restricted- scope- of- practice states, we expect to see approximately 146% increase in the geometric mean of HBPC utilization rate.

Discussion

Using 2019 Medicare fee-for-service data, we examined the association of state scope of practice regulations on the utilization of NP-HBPC. Contrary to expectations, we found higher rates of delivery of NP-HBPC in states with reduced and restricted scope-of-practice regulations.

Prior studies,^22,31,32 including one study focused on HBPC,¹² found that restricted scope-of-practice regulations limit availability and utilization of NP provided care. Osakwe et al, using 2017 Medicare PUF data,¹² conducted a provider-level analysis and found that in states with restricted scope-of-practice laws, compared to NPs, physicians and physician assistants had higher odds of providing HBPC. An important difference between the current study and prior analyses is that this was a state-level analyses and the sample was limited to NPs only. Furthermore, this article extends prior research by examining the potential influence of area-level race/ethnicity and socioeconomic conditions using more recent data.

Several factors may help explain why states with restricted scope-of-practice regulations were more likely to have greater uptake of NP-HBPC compared to full practice states. One potential factor is that in addition to scope-of-practice regulations, organizational characteristics of health systems employing NPs influence or create favorable practice environments for NPs.³³ Previous research has shown that practice settings that promote NP-role visibility, autonomy, and professional collaboration between NPs and physicians and/or administrators favor NPs, and are associated with greater retention of NPs.^34,35 Large HBPC health care delivery organizations in the private sector that play a dominant role in the delivery of HBPC may use a collaborative practice model between physicians and NPs, that while constraining some NP autonomy, may offer a rich interdisciplinary community and a culture of mutual respect that is appealing to some NPs. Consistent with this hypothesis is that several states with restricted scope-of-practice have multiple HBPC health care delivery organizations (e.g., Visiting Physicians Association, Optum Health and/or Landmark) with a large NP workforce. In addition, large HBPC health care delivery organizations may offer benefits such as compensation or reimbursement and administrative support, which prior work has found to be attractive to NPs.³⁶ Higher reimbursement for NP- HBPC visits under managed care organizations or large HBPC health care delivery organizations are important incentives that may attract NPs in restricted states. Efforts to expand access to HBPC in states with full scope-of-practice laws need to prioritize investment in training the NP workforce, and increase financial incentives for providing NP HBPC visits.

The large and growing NP workforce is critically important to expand access to HBPC in rural locations where they are most needed. In our study, compared to reduced and restricted states, several states with full scope-of-practice law had a large rural population(e.g., Montana, Maine, North Dakota[see Figure 1]), lower population density, fee-for-service population and less NP HBPC visits. These findings add to growing concerns about inadequate access to HBPC for homebound rural Medicare beneficiaries.³⁷

Prior studies have found that although states with full scope-of-practice have the highest numbers of NPs per capita,³⁸ the fastest NP growth and increase in number of patients seen by NPs occurred in states with reduced and restricted scope - of - practice.³⁹ More recent studies show that relaxing scope-of-practice restrictions do not affect the provision of low-value services (e.g., respiratory illness and low-back pain).⁴⁰ It is possible, however, that relaxed scope-of-practice could lead to more isolation and less interprofessional care, which may be unappealing to some NPs. Data on HBPC clinician team configurations necessary to deliver high-quality HBPC are needed to better understand more about the delivery of NP-HBPC in restricted states, and how NPs navigate the regulatory environment.

Future research should examine the impact of the practice environment of NPs on delivery of HBPC, such as team-based models of care, or the density of accountable care organizations in states with restricted scope-of-practice regulations.⁴¹ Finally, further work should examine the impact of NP scope-of - practice laws on HBPC provided by Medicare Advantage programs.

There are several limitations to this study. First, these findings might not generalize to NPs caring for other populations, such as those with Medicare Advantage coverage, which may differ socioeconomically from Medicare fee-for-service beneficiaries. Second, this was an exploratory, observational study; our findings reflect associations, not causal relationships about the role of scope-of-practice regulation in HBPC and should thus be treated as descriptive. Further research needs to employ more nuanced methods such as pseudo-experimental design focused on changes in state scope - of - practice regulations. Third, we may have underestimated NP participation in Medicare due to the prevalence of incident-to-billing under which care provided by NPs is billed under a physician’s National Provider Identifier number.⁴² Finally, while we accounted for the number of NP-HBPC providers, state ranking of total assisted living, the proportion of FFS Medicare beneficiaries and neighborhood-level socio-economic status and race and ethnicity, we did not account for other differences in states that may influence delivery of NP-HBPC including rurality, ratio of NP/physician and other primary care workforce (e.g., physician assistants).

In the present study, we found that utilization of NP-HBPC was greater in states with restricted scope-of-practice regulations. The highest rates of NP-HBPC were not in the states with full scope-of-practice regulations as hypothesized. We suggest several areas of further research needed to understand potential organizational-level sources of this variation in the utilization of NP-HBPC.

Key points:

• Nearly half of NPs providing HBPC (46%; n=7151) were in states with restricted scope of practice regulations.

• The NP-HBPC visit rates were higher in states with restricted and reduced scope-of-practice laws than full scope-of-practice states.

Why does this paper matter?

Understanding underlying mechanisms of how state scope-of-practice environment affects NP-HBPC delivery could help to develop scope-of-practice regulations that improve access to HBPC for the underserved homebound population.