title: Effectiveness of pre-operative clown intervention on psychological distress: A systematic review and meta-analysis.
abstract: OBJECTIVE
  This study aims to provide an overview of the current knowledge available on the effectiveness of pre-operative clown intervention on psychological distress in children and parents.
  
  
  METHODS
  PubMed, MEDLINE, Embase and PsycINFO databases were searched to identify relevant studies. Systematic review procedures were followed including a quality assessment. Meta-analysis of suitable studies was conducted.
  
  
  RESULTS
  Eight studies were included; six reported that clown intervention reduced children's pre-operative anxiety, while one found that children's pre-operative distress levels were unchanged. Two studies suggested that clown therapy decreased parents' state anxiety, while three others found inconsistent results. No differences were found on parents' trait anxiety score. Meta-analysis of the available data confirmed that clown intervention has a great effect to reduce children's pre-operative distress (six articles, 341 children, Hedges' g = 0.867, 95% confidence intervals: 0.374-1.360, P = 0.001), and also had a small-to-medium effect on reducing parents' state anxiety (five articles, 329 parents, Hedges' g = 0.338, 95% confidence intervals: 0.112-0.564, P = 0.003).
  
  
  CONCLUSIONS
  While significant variability existed between studies, the meta-analysis confirmed the effectiveness of pre-operative clown therapy on reducing psychological distress in children and parents. Larger randomised controlled trails and cross-cultural studies should be conducted to investigate the effectiveness of clown therapy in greater detail.
authors.affiliation: Department of Anaesthesiology, Guangzhou Women and Children's Medical Centre, Guangzhou, China.
authors.forename: Yongfu
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: School of Medicine, University of St Andrews, St Andrews, United Kingdom.
authors.forename: Yuan
authors.initials: Y
authors.lastname: Yang
authors.affiliation: School of Nursing, Li Ka Shing Faculty of Medicine, University of Hong Kong, Hong Kong, China.
authors.forename: Wing Yt
authors.initials: WY
authors.lastname: Lau
authors.affiliation: School of Health in Social Science, University of Edinburgh, Edinburgh, United Kingdom.
authors.forename: Samradhvi
authors.initials: S
authors.lastname: Garg
authors.affiliation: Department of Anaesthesiology, Guangzhou Women and Children's Medical Centre, Guangzhou, China.
authors.forename: Jianxin
authors.initials: J
authors.lastname: Lao
mesh_terms: D002648:Child; D006801:Humans; D027641:Laughter Therapy / Q000592:standards*; D057234:Preoperative Period; D013315:Stress, Psychological / Q000517:prevention & control*; D014925:Wit and Humor as Topic / Q000523:psychology*
keywords: anxiety; clown intervention; distress; meta-analysis; pre-operative; systematic review