The Impact of Using Mid-level Providers in Face-to-Face Primary Care on Health Care Utilization

There has been concern that greater use of nurse practitioners (NP) and physician assistants (PA) in face-to-face primary care may increase utilization and spending.

To evaluate a natural experiment within Kaiser Permanente in Georgia in the use of NP/PA in primary care.

From 2006 through early 2008 (the preperiod), each NP or PA was paired with a physician to manage a patient panel. In early 2008, NPs and PAs were removed from all face-to-face primary care. Using the 2006-2010 data, we applied a difference-in-differences analytic approach at the clinic level due to patient triage between a NP/PA and a physician. Clinics were classified into 3 different groups based on the percentage of visits by NP/PA during the preperiod: high (over 20% in-person primary care visits attended by NP/PAs), medium (5%-20%), and low (<5%) NP/PA model clinics.

Referrals to specialist physicians; emergency department visits and inpatient admissions; and advanced diagnostic imaging services.

Compared with the low NP/PA model, the high NP/PA model and the medium NP/PA model were associated with 4.9% and 5.1% fewer specialist referrals, respectively (P<0.05 for both estimates); the high NP/PA model and the medium NP/PA model also showed fewer hospitalizations and emergency department visits and fewer advanced diagnostic imaging services, but none of these was statistically significant.

We find no evidence to support concerns that under a physician's supervision, NPs and PAs increase utilization and spending.