Does Epidural Anesthesia Improve Survival After Intermediate-to-High–Risk Noncardiac Surgery?

Summary and Comment |
August 18, 2008

Does Epidural Anesthesia Improve Survival After Intermediate-to-High–Risk Noncardiac Surgery?

  1. Aaron J. Calderon, MD, FACP

A population-based cohort study shows that it might offer a small survival benefit.

  1. Aaron J. Calderon, MD, FACP

Previous studies have shown that, compared with parenteral opioid therapy, epidural anesthesia offers important benefits after major noncardiac surgery, including better analgesia and fewer postoperative pulmonary complications. Whether it leads to a higher survival rate has been the subject of debate because of conflicting evidence, mostly drawn from studies that had methodological or statistical power limitations.

Using administrative healthcare databases in a large retrospective population-based cohort study, researchers in Toronto analyzed 30-day mortality rates in patients (age, ≥40) who had undergone intermediate-to-high–risk noncardiac surgery. The original study population included 259,037 patients; 56,556 (22%) received perioperative epidural anesthesia. Propensity scores then were applied to produce a matched-pairs cohort, which consisted of 44,094 pairs of patients (1 of whom had received epidural anesthesia) without important intra-pair baseline differences.

Within the matched-pairs cohort, 30-day mortality was 1.74% for those who received epidural anesthesia and 1.95% for those who did not (relative risk, 0.89; P=0.02). This relative risk corresponded to an absolute risk reduction of 0.21% and a number needed to treat (NNT) of 477 to prevent 1 early death. Rates of postoperative mechanical ventilation and decompression laminectomy were not significantly different between groups.

Comment

Although this large cohort study showed a small, but significant, improvement in 30-day mortality in patients who received epidural anesthesia versus those who did not, the authors caution that these data are not compelling enough to recommend routine use of epidural anesthesia, given the high NNT and the borderline significance, despite the very large sample size. Even with propensity analysis, the researchers also were unable to control for many potential confounders; therefore, causality cannot be established. The authors and accompanying editorialists suggest that the results of this study should focus the medical community on the proven benefits of epidural anesthesia: namely, improved postoperative analgesia and fewer pulmonary complications. That it is safe and might offer a small survival benefit is just icing on the cake.

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