Nurse practitioners and physician assistants are complements to family medicine physicians.

Controlling the overall cost of medical care requires controlling the number of physician visits. Nurse practitioners and physician assistants (NPs/PAs) may function as lower-cost substitutes for physicians or they may complement physician services. The association between NP/PA and physician visits when NPs/PAs are not working as primary care providers (PCPs) has not been thoroughly studied. A sample of 400 family medicine patients drawn from 1 large multisite practice was studied using multiple logistic regression analysis. NPs/PAs did not function as PCPs during the study period. Patients were defined as outliers if they visited physicians more than 5 times in a year. Patients who visited NPs/PAs in non-retail clinics were significantly more likely to be physician visit outliers. Visits to NPs/PAs in retail clinics were not related to physician visits. NP/PA visits in standard medical office settings complement physician visits when the NPs/PAs were not working as PCPs in this large multisite practice. Health care reform proposals relying on increased use of NPs/PAs may be more cost-efficient if NPs/PAs are located in retail settings or function as PCPs.