APRN full practice authority, supply, and outcomes

Publication id: bae-2023-aprn-fpa-border
Status: verified Published: 2023 in Policy, Politics, & Nursing Practice (online ahead of print)

Citation: Bae, K., Norris, C., Shakya, S., & Timmons, E. (2023). Advanced practice registered nurse full practice authority, provider supply, and health outcomes: A border analysis. Policy, Politics, & Nursing Practice, 1–8. Bae et al. (2023) Download PDF

Related policy writing: Commonwealth Foundation brief on Maryland lessons for Pennsylvania; NC FPA materials on the policy briefs page.

Facts¶

Policy hook¶

The U.S. faces a critical primary care physician shortage, with 17,000–48,000 physicians projected to be needed by 2034. Advanced practice registered nurses (APRNs)—including nurse practitioners and certified nurse midwives—have the education and training to deliver primary care but are often prevented from doing so by state scope-of-practice laws that require physician supervision or collaboration. These regulatory barriers constrain both APRN workforce supply and patient access to primary care, particularly in underserved and rural areas.

Main finding¶

Maryland’s 2015 full practice authority law was associated with significant increases in APRN supply and improvements in health outcomes. In border county comparisons with Pennsylvania (which restricts APRN practice), Maryland had 22.4 more nurse practitioners per 100,000 residents and 0.6 more certified nurse midwives per 100,000 residents. Maryland border counties also showed better health outcomes: 2.8 percentage points fewer adults reporting poor or fair health and 0.354 fewer poor mental health days per month per person, with no significant difference in physician density between states.

Data and setting¶

• Data sources: National Plan and Provider Enumeration System (NPPES) 2016–2021 for provider density; County Health Rankings 2022 for health outcomes

• States compared: Maryland (adopted FPA in 2015) vs. Pennsylvania (no FPA for NPs or CNMs)

• Geographic scale: Full state and border county comparisons

• Health outcomes: Poor or fair health status, poor mental health days per month, preventable hospital stays for Medicare enrollees

• Population: Maryland and Pennsylvania residents, 2016–2021

Research design (plain language)¶

Border contiguity-based difference-in-differences analysis comparing geographically similar Maryland and Pennsylvania counties across state lines. Researchers examined provider density data (2016–2021) using NPPES to identify all practicing nurse practitioners and certified nurse midwives per 100,000 residents. Separate cross-sectional analysis examined county-level health outcomes (2022) using regression analysis with year fixed effects and state-level clustered standard errors. No additional covariates were included to avoid collider bias.

One caveat¶

The analysis lacks pre-2016 baseline data before Maryland’s 2015 FPA adoption, preventing traditional temporal difference-in-differences estimation and precluding causal claims—results are correlational and suggestive rather than definitive. Additionally, not all CNMs and NPs provide primary care; approximately 50% of CNMs and 70% of NPs provide primary care services, so effects may be diluted. Results are specific to the Maryland-Pennsylvania border comparison and may not generalize to other state FPA changes or countries where scope of practice is defined differently. Maryland’s unique all-payer healthcare rate-setting model may also influence results.

PDF or DOI¶

Download PDF

Why it matters¶

This border analysis provides compelling evidence that scope-of-practice restrictions materially constrain healthcare workforce supply and patient health. Maryland’s FPA generated a substantial increase in nurse practitioner density relative to Pennsylvania—the gap more than doubled between 2016 and 2020. Crucially, the paper demonstrates not just increased access but actual health improvements in Maryland border counties. This methodological approach—isolating FPA policy effects by comparing geographically similar communities across state boundaries—controls for regional differences and strengthens the argument for policy causality. The findings challenge the justification for restrictive regulations: there were no differences in physician supply between states, suggesting scope-of-practice restrictions don’t enhance physician recruitment but instead limit APRN mobility and patient access. For states considering FPA expansion, the research provides concrete evidence of dual benefits—increased provider supply and improved population health—at minimal regulatory cost.