Systematic review of enriched enrolment, randomised withdrawal trial designs in chronic pain: a new framework for design and reporting.

Enriched enrolment, randomised withdrawal (EERW) pain trials select, before randomisation, patients who respond by demonstrating a predetermined degree of pain relief and acceptance of adverse events. There is uncertainty over the value of this design. We report a systematic review of EERW trials in chronic noncancer pain together with a critical appraisal of methods and potential biases in the methods used and recommendations for the design and reporting of future EERW trials.

Evaluation of GW406381 for treatment of osteoarthritis of the knee: two randomized, controlled studies.

Context: GW406381 is an investigational, highly selective cyclooxygenase-2 (COX-2) inhibitor that is effective in animal models of central sensitization and of inflammatory pain.

Objective: To examine dose response for efficacy and safety of GW406381 in adults with osteoarthritis (OA) of the knee.

Design: Two randomized, double-blind, placebo- and positive-control studies: Study A, a 6-week nonflare design; Study B, a 12-week flare design.