Using NAMCS and NHAMCS to Examine Health Care by U.S. Physician Assistants and Nurse Practitioners

NAMCS and NHAMCS are the leading sources of nationally representative data on practice characteristics and provision of ambulatory services by office-based physicians (NAMCS) and in hospital-based outpatient clinics and emergency departments (NHAMCS).² It is important to clarify that, in NAMCS, patient visits were selected from a stratified sample of office-based physicians during a reporting week, as opposed to visits selected from physician practices as noted by Mafi and colleagues.¹ This means that visits, including those seen by PAs/NPs, were selected from the sampled physician’s patient log and subject to physician supervision. Office-based care by PAs/NPs, therefore, would be undercounted in NAMCS to the extent that PAs/NPs see their own patients independent of the physicians within the practice. Ongoing efforts are underway to expand NAMCS to capture PA/NP care more comprehensively in ambulatory settings.³ Research examining PA/NP care can also take advantage of NAMCS community health center data that select visits to physicians, PAs, NPs, and nurse midwives.²