title: Critical review of sham surgery clinical trials: Confounding factors analysis.
abstract: OBJECTIVE
  Sham surgery (placebo surgery) is an intervention that omits the step thought to be therapeutically necessary. In surgical clinical trials, sham surgery serves an analogous purpose to placebo drugs, neutralizing biases such as the placebo effect. A critical review was performed to study the statistical relevance of the clinical trials about sham surgery in the light of potential confounding factors.
  
  
  METHODS
  For the critical review 52 articles were included. The possible confounding factors have been studied using a structured interpretative research form designed by the authors. This form includes the following ten confounding factors: I), lack of homogeneity among inclusion/exclusion criteria. II), false double blind. III), lack of post-surgery double blind. IV), power of the study. V), sample characteristics. VI), lost patients to Follow-up. VII), gender distribution. VIII), age equilibrium. IX), lack of psychological patient evaluation. X), lack of psychiatric patient evaluation. In most of the studies, at least one confounding factor was present.
  
  
  RESULTS
  The analysis of the confounding factors showed that they could influence the reliability of the surgical placebo effects.
  
  
  CONCLUSIONS
  The validity of sham surgery should be reconsidered.
authors.affiliation: Department of Infectious, Parasitic, and Immune-Mediated Diseases, Epidemiology Unit, Reference Centre on Phylogeny, Molecular Epidemiology, and Microbial Evolution (FEMEM), National Institute of Health, 00161 Rome, Italy; Unit of Clinical Pathology and Microbiology, University Campus Bio-Medico of Rome, Italy.
authors.forename: Massimo
authors.initials: M
authors.lastname: Ciccozzi
authors.affiliation: Faculty of Medicine, Campus Bio-Medico University of Rome, Italy.
authors.forename: Rosa
authors.initials: R
authors.lastname: Menga
authors.affiliation: School of Law, University of Camerino, 62032 Camerino, Italy.
authors.forename: Giovanna
authors.initials: G
authors.lastname: Ricci
authors.affiliation: Medical Direction of Campus Bio-Medico Hospital, University Campus Bio-Medico of Rome, Italy.
authors.forename: Massimiliano Andrea
authors.initials: MA
authors.lastname: Vitali
authors.affiliation: Unit of Clinical Pathology and Microbiology, University Campus Bio-Medico of Rome, Italy.
authors.forename: Silvia
authors.initials: S
authors.lastname: Angeletti
authors.affiliation: School of Medical Sciences and Health Products, University of Camerino, 62032 Camerino, Italy.
authors.forename: Ascanio
authors.initials: A
authors.lastname: Sirignano
authors.affiliation: Institute of Philosophy of Scientific and Technological Practice, University Campus Bio-Medico of Rome, Italy.
authors.forename: Vittoradolfo
authors.initials: V
authors.lastname: Tambone
keywords: Clinical trial/epidemiology; Clinical trials/ethics; Medical ethics; Placebo effect; Public health; Sham surgery