Identifying the participant characteristics that predict recruitment and retention of participants to randomised controlled trials involving children: a systematic review.

Randomised controlled trials (RCTs) are recommended as the 'gold standard' in evaluating health care interventions. The conduct of RCTs is often impacted by difficulties surrounding recruitment and retention of participants in both adult and child populations. Factors influencing recruitment and retention of children to RCTs can be more complex than in adults. There is little synthesised evidence of what influences participation in research involving parents and children.