Assessing the impact of patient and public involvement on recruitment and retention in clinical trials: a systematic review

Background and aims Patient and public involvement (PPI) is research being carried out ‘with’ or ‘by’ patients and/or members of the public rather than ‘to’, ‘about’ or ‘for’ them. Some evidence suggests that PPI in clinical trials may improve recruitment and retention. We undertook a systematic review to determine whether or not this is confirmed by quantitative evidence. We also explored whether the impact on recruitment and retention varies according to context and PPI method.