Does it matter who the anesthesiologist is for my heart surgery

Patients choose surgeons carefully. Conversely, patients typically accept whatever anesthesiologist is assigned, and rarely know the name of their anesthesiologist until the day of surgery. Hospital administrators and operating room directors regularly move and reschedule anesthesiologists to cover any case and maximize efficiency. We are perceived as interchangeable cogs in the perioperative machine, at least within groups (e.g., those who routinely do cardiac cases). The assumption underlying this practice is that any similar anesthesiologist will do, and that substitution of Anesthesiologist A for Anesthesiologist B does not change patient outcome. In this issue of Anesthesia & Analgesia, Glance et al. 1 demonstrate that these assumptions may be incorrect and indeed harmful to patients. The uncomfortable finding of Glance et al. is that the individual anesthesiologist has a substantial impact on outcome after coronary artery bypass graft surgery. The authors investigated a large database of cardiac surgical patients in New York State. They defined a composite end point of death, postoperative myocardial infarction, renal failure, or stroke. They adjusted the risk of this composite outcome for patient demographics, severity of cardiac disease, and patient comorbidities. In modeling this adjusted risk of the composite end point by anesthesiologist and hospital, they demonstrated significant variability in the rate of death or major morbidity after coronary artery bypass graft surgery by anesthesiologist. This risk was independent of hospital variability, patient comorbidities, or stratifying across low-risk and high-risk patients. The magnitude of the anesthesiologist effect observed by Glance et al. 1 is significant. The risk-adjusted rate of the composite outcome occurred in 3.33% of patients whose anesthesiologists were in the worst quartile and occurred in 1.82% of patients whose anesthesiologists were in the best quartile. This translates to an absolute risk difference of 1.51% for the composite outcome between best and worst quartile of anesthesiologists. The number needed to harm was 66. That is, for every 66 patients who are assigned to an anesthesiologist in the worst quartile, rather than an anesthesiologist in the best quartile, 1 will have a bad outcome because of the anesthesiologist assigned to them. If one compares the risk for worst 10% of anesthesiologists (4.57%) to that for the best 10% of anesthesiologists (1.31%), the absolute risk difference is 3.26%. The number needed to harm is just 31! To put this in perspective, the number needed to treat of aspirin in patients with unstable angina was 20. 2 What should we make of Glance et al.’s 1 findings? First, we should consider that there are important limitations of the analysis. For example, the authors controlled for hospital effects, but not for the effect of variability in the individual surgeon. Their demonstration of low correlation between anesthesiologists and surgeons reduces the potential that anesthesiologist quality may be a proxy for surgeon quality. Otherwise, the results could be explained away by saying that high-quality surgeons simply choose to work with high-quality anesthesiologists. Their analysis does not support this alternative interpretation, but it does not entirely eliminate this possible explanation.