In stark contrast to a 2010 investigation suggesting that nurse anesthetists frequently provide care unsupervised by physician anesthesiologists, researchers at the University of Texas Medical Branch and the American Society of Anesthesiology’s (ASA) Department of Health Policy have found that the Medicare billing code at the center of that trial—modifier QZ—does not seem to be a valid surrogate for care in which no anesthesiologist is present. These findings, the