Advanced practice roles for nurses in tomorrow's healthcare systems.

Advanced practice nurses (APNs) have traditionally been a diverse group in terms of titles, education, credentials, and roles. The classification of APN usually encompasses the nurse practitioner (NP), certified nurse midwife (CNM), certified registered nurse anesthetist (CRNA), and clinical nurse specialist (CNS). NP, CRNA, and CNM roles have been more clearly delineated than the CNS roles.