Back to the future: medical reversals and perioperative medicine

While most of us were enjoying the pleasures of an idle summer, a publication in Mayo Clinic Proceedings created a stir in the esoteric world of evidence-based medicine. The subject of interest was medical reversal, a phenomenon in which ‘‘a medical practice is found to be inferior to some lesser or prior standard of care’’. Prasad et al. reviewed original articles published in the New England Journal of Medicine from 2001 to 2010 in their endeavour to determine if new evidence advanced, confirmed, or rejected current medical practices. Seven hundred fiftysix (56%) of the 1,344 manuscripts reviewed found a new therapy superior to an older treatment, 138 (10%) confirmed the utility of a current therapy, and 165 (12%) found new practices inferior to present care. One hundred forty-six (40%) of the 363 studies evaluating an existing medical practice found the current therapy inferior to a lesser or earlier standard of care. These rejections of current practice for an older treatment (or no treatment at all) cut across classes of medical care, including anesthesia. Cited examples from perioperative medicine included bispectral index monitoring, mild hypothermia for an intracranial aneurysm clipping, use of a pulmonary artery catheter for high-risk surgical patients, coronary revascularization before elective vascular surgery, epidurals in early labour, and use of aprotinin in cardiac surgery. The reaction to Prasad’s findings was swift and critical. An accompanying editorial stated, ‘‘[T]he proportion of medical reversals seems alarmingly high. At a minimum, it poses major questions about the validity and clinical utility of a sizeable portion of everyday medical care.’’ The blog, Science-Based Medicine, noted, ‘‘[T]his highlights the fact that some current practices are useless or less than optimal and need to be reexamined.’’ Even the New York Times got in on the action by leading with the headline, ‘‘Medical Procedures May Be Useless, or Worse.’’ Both the evidence base for medical practice and the practice itself were under attack. Patients and clinicians alike could be left wondering how a supposedly science-based practice could have been wrong so frequently. Prasad identified a common narrative among the reversals noting that, ‘‘[a]lthough there is a weak evidence base for some practice, it gains acceptance largely through vocal support from prominent advocates and faith that the mechanism of action is sound. Later, future trials undermine the therapy, but removing the contradicted practice often proves challenging.’’ Does this sound familiar? Let us consider the saga of perioperative beta-blockade from Prasad’s perspective of medical reversal. In 1996, Mangano published results of a 200-patient placebo-controlled trial evaluating a seven-day perioperative course of atenolol on a composite outcome of cardiac mortality and morbidity. Six patients who died in hospital were excluded. Of those surviving to hospital discharge, 12 of 99 placebo patients died within six months of surgery compared with four of 95 patients receiving atenolol (crude relative risk [RR] 0.35; 95% confidence interval [CI] 0.1 to 1.0). Several years later, Poldermans G. L. Bryson, MD (&) Department of Anesthesiology, The Ottawa Hospital, The University of Ottawa, 1053 Carling Avenue, Box 249C, Ottawa, ON K1Y 4E9, Canada e-mail: glbryson@ottawahospital.on.ca

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