Editor's Response: Group vs Categorical Data in Epidural Studies

Dear Editor,In their letter, Nampiaparampil and Engel raise a number of concerns about the study of Pinto et al. [1], and their exchange provides us a valuable opportunity to discuss study design and interpretation. Some of their concerns can be questioned, but they do reflect the irritation felt by practitioners who find their procedures being assaulted, seemingly unfairly, by academics who do not practice in the field under review. The concern that studies differed in the doses used are not fair criticisms of a review, because in practice there is no uniformity of dose for epidural injections. Nor is it a fair criticism that studies may have been compromised because the injection was at the wrong level, for there is no evidence that epidural injections have to be that target-specific.Of some relevance is the criticism that blind injections should not be lumped with fluoroscopically guided injections, for it has been shown that blind injections often miss the epidural space completely. In their letter of response, Pinto et al. retort that they did perform a subgroup analysis of fluoroscopically guided …