EXPRESSION OF CONCERN: Efficacy of psilocybin for treating symptoms of depression: systematic review and meta-analysis

The journal and the authors are investigating the problem.The study analysed data from randomised trials of psilocybin for the treatment of depression in adults.A methodological concern has been raised about an error in the calculation of standardised mean differences.This is likely to have overestimated the benefits of psilocybin.The authors are reviewing and responding to the error and its implications for the findings and conclusions of the paper.The authors' response will be reviewed by The BMJ who will decide what further action is needed.