Osteoarthritis (OA) is a highly prevalent condition that imposes substantial burden on the individuals affected. Presently there are limited treatments available to control symptoms. Current United States Food and Drug Administration (FDA) and European Medicine Agency approved agents consist of corticosteroids and viscosupplements (hyaluronate). These are not first-line recommended therapies from treatment guidelines based on their limited efficacy profiles. This is in large part due to the inability to achieve a minimum clinically important difference over placebo. When considering clinical trial design, the challenges of which placebo to choose, its volume, injection frequency, the use of injection guidance, concomitant local anaesthetic use, patient baseline disease presentation (bilateral versus unilateral disease, concomitant presence of inflammatory features/effusion, disease severity, baseline pain) all create substantial opportunity for heterogeneity in what is already a challenging clinical trial environment.
As the placebo effect can be attributed to the individual or related to the study protocol, assessment of the placebo effect utilising individual patient data (IPD) meta-analysis will give insight into the different predictors of placebo response and influence subsequent implementation of clinical designs with lowered placebo response.
Using IPD, a number of analyses of placebo-controlled trial data from different intra-articular injection trials for osteoarthritis will be conducted to ascertain the mechanisms behind placebo response in intra-articular trials in osteoarthritis. Placebo randomized control trials of intra-articular
glucocorticoids and viscosupplements will be identified via a systematic literature review. Intervention characteristics, trial characteristics, disease severity and outcomes will be analysed.