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

Abstract

To examine the impact of state-granted nurse practitioner (NP) independence on patient-level quality, service utilization, and referrals. 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. 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. 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. 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. Findings do not support a quality-scope of practice relationship.