Does the Regulatory Environment Affect Nurse Practitioners’ Patterns of Practice or Quality of Care in Health Centers?

OBJECTIVE: To examine the impact of state-granted nurse practitioner (NP) independence on patient-level quality, service utilization, and referrals. DATA SOURCES/STUDY SETTING: The National Ambulatory Medical Care Survey's community health center (HC) subsample (2006-2011). Primary analyses included approximately 6,500 patient visits to 350 NPs in 220 HCs. STUDY DESIGN: Propensity score matching and multivariate regression analysis were used to estimate the impact of state-granted NP independence on each outcome, separately. Estimates were adjusted for sampling weights and NAMCS's complex design. DATA COLLECTION/EXTRACTION METHODS: Every "NP-patient visit unit" was isolated using practitioner and patient visit codes and, using geographic identifiers, assigned to its state-year and that state-year's level of NP independence based on scope of practice policies. Nine outcomes were specified using ICD-9 codes, standardized drug classification codes, and NAMCS survey items. PRINCIPAL FINDINGS: After matching, no statistically significant differences in quality were detected by states' independence status, although NP visits in states with prescriptive independence received more educational services (aIRR 1.66; 95 percent CI 1.09-2.53; p = .02) and medications (aIRR 1.26; 95 percent CI 1.04-1.53; p = .02), and NP visits in states with practice independence had a higher odds of receiving physician referrals (AOR 1.88; 95 percent CI 1.10-3.22; p = .02) than those in restricted states. CONCLUSIONS: Findings do not support a quality-scope of practice relationship.