Rebuttal for: Postoperative complications of epidural analgesia at hysterectomy for gynecologic malignancies: an analysis of the National Surgical Quality Improvement Program.

Ackroyd and colleagues’ study[1][1] links epidural analgesia with negative postoperative outcomes based on a propensity matching model intended to remove the bias present in observational datasets. We question their approach for several reasons. First, covariates used to create their model are not