Abstract
Studies have established that nurse practitioners (NPs) deliver primary care comparable to physicians in quality and cost, but most focus on Medicare, a program that reimburses NPs less than physicians. In this retrospective cohort study, we evaluated the quality and cost implications of receiving primary care from NPs compared to physicians in 14 states that reimburse NPs at the Medicaid fee-for-service (FFS) physician rate (i.e., pay parity). We linked national provider and practice data with Medicaid data for adults with diabetes and children with asthma (2012-2013). We attributed patients to primary care NPs and physicians based on 2012 evaluation & management claims. Using 2013 data, we constructed claims-based primary care quality measures and condition-specific costs of care for FFS enrollees. We estimated the effect of NP-led care on quality and costs using: (1) weighting to balance observable confounders and (2) an instrumental variable (IV) analysis using differential distance from patients' residences to primary care practices. Adults with diabetes received comparable quality of care from NPs and physicians at similar cost. Weighted results showed no differences between NP- and physician-attributed patients in receipt of recommended care or diabetes-related hospitalizations. For children with asthma, costs of NP-led care were lower but quality findings were mixed: NP-led care was associated with lower use of appropriate medications and higher rates of asthma-related emergency department visits but similar rates of asthma-related hospitalization. IV analyses revealed no evidence of differences in quality between NP- and physician-led care. Our findings suggest that in states with Medicaid pay parity, NP-led care is comparable to physician-led care for adults with diabetes, while associations between NP-led care and quality were mixed for children with asthma. Increased use of NP-led primary care may be cost-neutral or cost-saving, even under pay parity.