Predicting postoperative analgesia outcomes: NNT league tables or procedure-specific evidence? † †Declaration of interest. The authors are members of the Procedure Specific Postoperative Pain Management (PROSPECT) Group, which conducts procedure-specific systematic reviews of the literature using the Cochrane Protocol, supplements these with evidence from other procedures and from clinical practice, and produces guidelines for the management of postoperative pain. The PROSPECT Group is funded by an unrestricted educational grant from Pfizer Inc., who provided financial support for the writing of this article.