title: Reporting and handling missing outcome data in mental health: a systematic review of Cochrane systematic reviews and meta-analyses.
abstract: OBJECTIVE
  The purpose of the study was to provide empirical evidence about the reporting of methodology to address missing outcome data and the acknowledgement of their impact in Cochrane systematic reviews in the mental health field.
  
  
  METHODS
  Systematic reviews published in the Cochrane Database of Systematic Reviews after January 1, 2009 by three Cochrane Review Groups relating to mental health were included.
  
  
  RESULTS
  One hundred ninety systematic reviews were considered. Missing outcome data were present in at least one included study in 175 systematic reviews. Of these 175 systematic reviews, 147 (84%) accounted for missing outcome data by considering a relevant primary or secondary outcome (e.g., dropout). Missing outcome data implications were reported only in 61 (35%) systematic reviews and primarily in the discussion section by commenting on the amount of the missing outcome data. One hundred forty eligible meta-analyses with missing data were scrutinized. Seventy-nine (56%) of them had studies with total dropout rate between 10 and 30%. One hundred nine (78%) meta-analyses reported to have performed intention-to-treat analysis by including trials with imputed outcome data. Sensitivity analysis for incomplete outcome data was implemented in less than 20% of the meta-analyses.
  
  
  CONCLUSIONS
  Reporting of the techniques for handling missing outcome data and their implications in the findings of the systematic reviews are suboptimal.
authors.affiliation: Department of Hygiene and Epidemiology, School of Medicine, University of Ioannina, University Campus, Ioannina, Greece.
authors.forename: Loukia M
authors.initials: LM
authors.lastname: Spineli
authors.affiliation: Department of Orthodontics and Dentofacial Orthopedics, Dental School, Medical Faculty, University of Bern, Corfu, Switzerland.|Private practice, Corfu, Greece.
authors.forename: Nikolaos
authors.initials: N
authors.lastname: Pandis
authors.affiliation: Department of Hygiene and Epidemiology, School of Medicine, University of Ioannina, University Campus, Ioannina, Greece.
authors.forename: Georgia
authors.initials: G
authors.lastname: Salanti
mesh_terms: D003198:Computer Simulation; D003627:Data Interpretation, Statistical; D019317:Evidence-Based Medicine; D006801:Humans; D001523:Mental Disorders / Q000175:diagnosis / Q000453:epidemiology* / Q000628:therapy*; D015201:Meta-Analysis as Topic; D015233:Models, Statistical; D017063:Outcome Assessment, Health Care / Q000379:methods*; D015995:Prevalence; D016032:Randomized Controlled Trials as Topic / Q000706:statistics & numerical data*; D015203:Reproducibility of Results; D012107:Research Design; D012196:Review Literature as Topic; D018401:Sample Size; D012680:Sensitivity and Specificity; D016896:Treatment Outcome
keywords: intention-to-treat analysis; last observation carried forward; missing outcome data; psychiatric trials; systematic reviews