There is little difference in complication and mortality rates in states that allow CRNA-only anesthesia and states that require physician-supervised anesthesia care, according to a 6-year study of surgical outcomes from a Medicare database.

Since 2001, when Medicare began allowing states to opt out of requirements for physician-supervised anesthesia care, 15 mostly rural states have opted out. In a study funded by the American Association of Nurse Anesthetists, Brian Dulisse, PhD, and Jerry Cromwell, PhD, of the Research Triangle Institute in Waltham, Mass., extracted outcomes data from 480,000 surgical cases performed between 1999 and 2005 in states that required physician supervision, as well as 14 opt-out states. (California opted out in 2009 and was not included.)

In the opt-out states, nurse anesthetists provided the anesthesia in 1 out of 5 cases; in states requiring supervision, nurse anesthetists provided anesthesia in 1 out of 10 cases. The percentage of cases done by CRNAs increased from 17.6% to 21% in the opt-out states after they began allowing CRNAs to practice alone, according to the study, published in the August issue of Health Affairs.

As the number of CRNA-only cases increased in the opt-out states, the complication rate did not change substantially. Before opting out, the odds ratio for complications associated with CRNA cases was 0.798. After opting out, when more cases were performed solely by CRNAs, the odds ratio for complications was 0.813, according to the study. Similarly, there was little change in complication rates for states that did not opt out.

Mortality rates went up and down in opt-out states, ranging from 1.76 to 3.01 for CRNA-only cases and 1.45 to 2.92 for CRNA-physician team cases. "Despite the shift to more anesthetics performed by nurse anesthetists, no increase in adverse outcomes was found," write the authors.

"We find no evidence that opting out of the oversight requirement harms patients," says Dr. Cromwell. "Based on these findings we recommend that CMS repeal the supervision rule."

Kent Steinriede

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