Methodological Issues in Explaining Maternal Outcomes

Abstract

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.

Commentary: What Conclusions Can We Draw from Recent Analyses of Anesthesia Provider Model and Patient Outcomes?

“…This study builds upon the authors' prior work, which describes five distinct anesthesia provider models based on reports from 613 hospitals in eight states (Minnick and Needleman 2008). In the present study, they compare rates of mortality and key complications among mothers following delivery at facilities distinguished by the relative participation of anesthesiologists and Certified Registered Nurse Anesthetists (CRNAs) in obstetric anesthesia care at each hospital.…”

Anesthesia Provider Model, Hospital Resources, and Maternal Outcomes

“…The survey variables pertaining to resource and anesthesia provider model utilized in this analysis were chosen based on item response rates and variation across models. Details regarding the survey and variables formation may be found in an earlier paper (Minnick and Needleman 2008).…”

“…This characterization ignores potentially large variations across hospitals in the scope of CRNA practice when both anesthesiologists and CRNAs are present. In a recent survey by the authors of obstetrical anesthesia services, we found there are at least five anesthesia provider models based on providers' procedure initiation privileges (e.g., the initiation of spinal, epidural, and general anesthesia) (Minnick and Needleman 2008). The survey also found systematic variations in anesthesia, nursing, and obstetrical medicine resources across obstetrical anesthesia provider models that raise the possibility that provider model may be a proxy for other clinical resource variables usually left unmeasured in typically used databases.…”

“…Based upon the survey, hospitals were classified into one of five anesthesia models: anesthesiologist only (ANES‐only); CRNA‐only; both anesthesiologists and CRNAs practicing at the hospital, with an anesthesiologist required to be present at the initiation of all planned cesarean sections (ANES–CRNA I); both anesthesiologists and CRNAs practicing at the hospital, with an anesthesiologist not required to be present at the initiation of all planned cesarean sections (ANES–CRNA II); and a small group of hospitals in which the anesthesia model differed between labor and delivery and general operating areas (Mixed). Previous work established that this assignment of anesthesia models captured the degree of CRNA supervision more precisely than using a single model designation in institutions where both CRNAs and anesthesiologists practice (Minnick and Needleman 2008).…”

“…Using survey data, we constructed indicator variables that describe the organization of obstetrical services and obstetrical anesthesia. The variables were identified as potentially associated with maternal outcomes as a result of a literature review and deliberations of a panel of experts (Minnick and Needleman 2008). These included the presence of an obstetric anesthesia provider 24 hours per day, facilities to perform a nonemergency cesarean delivery in the labor and delivery area, the proportion of patients reported to labor and deliver in the same room, the number of health care personnel present at a cesarean procedure, minutes to transport a patient for an emergency cesarean delivery from site of labor, and volume (defined as the number of births at the hospital in the year studied divided by 1,000 to make interpretation of the results easier).…”