Nurse practitioners and physician assistants can alleviate some of the primary care shortage facing the United States, but their scope-of-practice is limited by state regulation. This study reports both cross-sectional and longitudinal trends in state scope-of-practice regulations for nurse practitioners and physician assistants over a 10-year period. Regulations from 2001 to 2010 were compiled and described with respect to entry-to-practice standards, physician involvement in treatment/diagnosis, prescriptive authority, and controlled substances. Findings indicate that most states loosened regulations, granting greater autonomy to nurse practitioners and physician assistants, particularly with respect to prescriptive authority and physician involvement in treatment and diagnosis. Many states also increased barriers to entry, requiring high levels of education before entering practice. Knowledge of state trends in nurse practitioner and physician assistant regulation should inform current efforts to standardize scope-of-practice nationally.
