Conclusions regarding the role of expectations in placebo analgesia studies may depend on how we investigate it: A meta-analysis, systematic review, and proposal for methodological discussions

Expectations are highlighted as a key component in placebo effects. However, there are different approaches to whether and how placebo studies should account for expectations, and the direct contribution has yet to be estimated in meta-analyses. Using different methodological approaches, this meta-analysis and systematic review examines the extent to which expectations contribute to pain in placebo studies.