Prescribing trends by nurse practitioners and physician assistants in the United States

Abstract

As an important step in analyzing the role of nurse practitioners (NPs) and physician assistants (PAs), we examined their prescribing behavior. The intent is to study the characteristics of providers and patients, and the type of prescriptions written by NPs and PAs in primary care and to compare these activities to physicians. The National Ambulatory Medical Care Survey (NAMCS) database was examined for prescriptions written by primary care clinicians (family and general medicine, internal medicine, and general pediatrics). A representative sample of 88,346 primary care visits over a 6-year period (1997-2002) was analyzed in which a prescription was written by an NP, a PA, or a physician in an urban or rural setting. The characteristics of all the patients seen were similar for geographical region of visit, age, and gender, but differed by ethnicity and race. An NP or a PA was the provider of record for 5% of the primary care visits in the NAMCS database. The three clinician types were likely to write at least one prescription for 70% of all visits, and the mean number of prescriptions was 1.3-1.5 per visit (range 0-5) depending on the provider. PAs were more likely to prescribe a controlled substance for a visit than a physician or an NP (19.5%, 12.4%, 10.9%, respectively). Only in nonmetropolitan settings did differences emerge. In rural areas, NPs wrote significantly more prescriptions than physicians and PAs. We suggest that NPs and PAs may provide a role that is similar to that of physicians in primary care based on prescribing behavior. The prescribing behavior of PAs and NPs parallels that of physicians by the number of medications per visit, the types of therapeutic classes, and the type of patient. However, in nonmetropolitan areas, prescribing differences emerge between the three types of providers that bear further exploration.