Quality of Care in Anesthesia

Section One
Summary of Pertinent Quality of Care Studies and Data

In the November 2008 online issue of Health Services Research, researchers Jack Needleman, PhD, MS, and Ann F. Minnick, PhD, RN, FAAN, published the results of a national study titled “Anesthesia Provider Model, Hospital Resources, and Maternal Outcomes.” Using a geographically broad sample of hospitals in seven states, Needleman/Minnick sought to determine the ability of anesthesia provider models and hospital resources to explain maternal outcome variations. According to the researchers, “Given that almost 4 million U.S. women give birth annually, determining improvement strategies is important (National Center for Health Statistics 2005).” [page 3]

The results of the Needleman/Minnick study revealed that obstetrical (OB) anesthesia is equally safe in hospitals that use only Certified Registered Nurse Anesthetists (CRNAs) or a combination of CRNAs and physician anesthesiologists, compared with hospitals that use only anesthesiologists. These results confirmed the results of a 2007 study using Washington state data that revealed no difference in OB anesthesia complication or mortality rates between hospitals that use only CRNAs compared with hospitals that use only anesthesiologists (Simonson, et al—see entry in this booklet.).

A.  Rationale for Undertaking Study
According to the researchers, high cesarean delivery rates and extensive use of epidural pain relief make anesthesia an important component of obstetrical care. This study was undertaken:

• To identify any systematic differences in outcomes between hospitals using CRNA-only, anesthesiologist-only, and CRNA/anesthesiologist staffing models.
• To determine the ability of anesthesia provider models and hospital resources to explain maternal outcome variations.

B. Background
The study involved more than 1.14 million OB patients from 369 hospitals in seven states, including California, Florida, Kentucky, New York, Texas, Washington, and Wisconsin. Participating hospitals met the following conditions: reported at least one live birth in the 2002 American Hospital Association Annual Survey, provided at least one year of discharge data to state agencies, and responded to a 2004 survey on organization and resources of obstetrical services. Approximately 10 percent of all births in U.S. hospitals from 1999-2001 occurred in these facilities.

Data was assembled from the information given by the hospitals to their state agencies and from the 2004 survey on obstetric services.

Four outcomes were coded from the discharge data: death, anesthesia complications, nonanesthesia maternal complications, and obstetrical trauma.  Hospitals were classified into one of five anesthesia models: anesthesiologist-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; both anesthesiologists and CRNAs practicing at the hospital, with an anesthesiologist not required to be present at the initiation of all planned cesarean sections; and hospitals in which the anesthesia model differed between labor/delivery and general operating areas.

Variables such as the organization of OB services and OB anesthesia, patient characteristics, and hospital characteristics were taken into consideration.

The researchers conducted a logistic regression of each outcome measure on a full model that included the anesthesia model, other hospital characteristics, and patient characteristics. In addition, because anesthesia and other complications were more prevalent in patients undergoing cesarean deliveries, a logistic regression was also conducted on a full model for each outcome measure restricted to cesarean patients.

Significant Findings and Patterns. Several important findings and patterns emerged from the Needleman/Minnick study:

• The death rate was very low (0.007 percent), and anesthesia complications occurred in less than 1 percent of the sample.
• The most common anesthesia model was anesthesiologist-only (39 percent); the second-most common was CRNA-only (23 percent).
• Death rates were highest in hospitals with anesthesiologist-only models, although the differences were not statistically significant.
• Anesthesia complication rates were lower in the CRNA-only hospitals (0.23 percent) than in the anesthesiologist-only hospitals (0.27 percent). Rates in the other hospitals varied from 0.24 percent to 0.37 percent, with the differences not being statistically significant from the anesthesiologist-only hospitals.
• Multivariate analysis found no systematic differences between hospitals with anesthesiologist-only models and hospitals with models using CRNAs. There was no consistent pattern associating other hospital or patient characteristics with outcomes.

C. Conclusions
Needleman/Minnick concluded the following:

• Hospitals that use only CRNAs, or a combination of CRNAs and anesthesiologists, do not have systematically poorer maternal outcomes compared with hospitals using anesthesiologist-only models.
• At least in the area of obstetrical services, there may be no gain in anesthesia safety from restricting which licensed providers can provide anesthesia services. The use of CRNAs may make it possible to provide obstetric anesthesia coverage where anesthesiologists are not available because of cost or other factors pertaining to regulation and payment.

Next: Simonson OB Study

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