title: Outcome reporting bias in evaluations of public health interventions: evidence of impact and the potential role of a study register.
abstract: BACKGROUND
  Systematic reviews of the effectiveness of interventions are increasingly used to inform recommendations for public health policy and practice, but outcome reporting bias is rarely assessed.
  
  
  METHODS
  Studies excluded at full-text stage screening for a systematic review of a public health intervention were assessed for evidence of study exclusion resulting from non-reporting of relevant outcomes. Studies included in the review were assessed for evidence of outcome reporting bias and the impact that this had on the evidence synthesised using a formal tool (Outcome Reporting Bias in Trials (ORBIT)).
  
  
  RESULTS
  None of the reports excluded at full-text stage were excluded because of non-reporting of relevant outcomes. Of the 26 included papers, six were identified as having evidence of missing or incompletely reported outcomes, with 64% of unreported or incompletely reported outcomes identified as to leading to a high risk of bias according to the ORBIT tool. Where there was evidence of the effectiveness of interventions before an assessment of outcome reporting bias was undertaken, identifying possible instances of outcome reporting bias generally led to a reduction in the strength of evidence for the effectiveness of the interventions.
  
  
  CONCLUSIONS
  The findings from this single evaluation provide empirical data to support the call for a prospective public health interventions study registry to aid the identification of unreported or incompletely reported outcomes. Critical appraisal tools can also be used to identify incompletely reported outcomes, but a tool such as ORBIT requires development to be suitable for public health intervention evaluations.
authors.affiliation: Peninsula Technology Assessment Group, Peninsula Medical School, University of Exeter, Veysey Building, Salmon Pool Lane, Exeter EX2 4SG, UK. mark.pearson@pms.ac.uk
authors.forename: Mark
authors.initials: M
authors.lastname: Pearson
authors.forename: Jaime
authors.initials: J
authors.lastname: Peters
mesh_terms: D015982:Bias; D003625:Data Collection / Q000592:standards / Q000706:statistics & numerical data; D019317:Evidence-Based Medicine; D006801:Humans; D017063:Outcome Assessment, Health Care / Q000592:standards*; D011634:Public Health / Q000379:methods*; D016032:Randomized Controlled Trials as Topic / Q000592:standards*; D012042:Registries; D012196:Review Literature as Topic; D016896:Treatment Outcome