Methodological issues in explaining maternal outcomes: anesthesia provider characterizations and resource variation.

Anesthesia provider models were characterized based on responsibilities and technique privileges and the distribution of clinical resource and process variables using a survey of 1,135 hospitals offering obstetric care in eight representative states. The resulting models were then analyzed by resource availability. In the 40% of hospitals where certified registered nurse anesthetists (CRNAs) and anesthesiologists both practiced obstetric anesthesia, three models emerged based on consistency of privileges within the institution and permission to initiate procedures. Hospitals in which only anesthesiologists practice and those in which CRNAs practice was most restricted had more resources than other hospitals surveyed. Traditional characterizations of provider fail to capture differences in technique privileges. Clinical resource variables and the scope of technique privileges should be included in the study of anesthesia provider credentials on outcomes.