title: Reporting of loss to follow-up information in randomised controlled trials with time-to-event outcomes: a literature survey.
abstract: BACKGROUND
  To assess the reporting of loss to follow-up (LTFU) information in articles on randomised controlled trials (RCTs) with time-to-event outcomes, and to assess whether discrepancies affect the validity of study results.
  
  
  METHODS
  Literature survey of all issues of the BMJ, Lancet, JAMA, and New England Journal of Medicine published between 2003 and 2005. Eligible articles were reports of RCTs including at least one Kaplan-Meier plot. Articles were classified as "assessable" if sufficient information was available to assess LTFU. In these articles, LTFU information was derived from Kaplan-Meier plots, extracted from the text, and compared. Articles were then classified as "consistent" or "not consistent". Sensitivity analyses were performed to assess the validity of study results.
  
  
  RESULTS
  319 eligible articles were identified. 187 (59%) were classified as "assessable", as they included sufficient information for evaluation; 140 of 319 (44%) presented consistent LTFU information between the Kaplan-Meier plot and text. 47 of 319 (15%) were classified as "not consistent". These 47 articles were included in sensitivity analyses. When various imputation methods were used, the results of a chi2-test applied to the corresponding 2 × 2 table changed and hence were not robust in about half of the studies.
  
  
  CONCLUSIONS
  Less than half of the articles on RCTs using Kaplan-Meier plots provide assessable and consistent LTFU information, thus questioning the validity of the results and conclusions of many studies presenting survival analyses. Authors should improve the presentation of both Kaplan-Meier plots and LTFU information, and reviewers of study publications and journal editors should critically appraise the validity of the information provided.
authors.affiliation: Institute for Quality and Efficiency in Health Care (IQWiG), Dillenburger Str. 27, 51105 Cologne, Germany. elke.vervoelgyi@iqwig.de
authors.forename: Elke
authors.initials: E
authors.lastname: Vervölgyi
authors.forename: Mandy
authors.initials: M
authors.lastname: Kromp
authors.forename: Guido
authors.initials: G
authors.lastname: Skipka
authors.forename: Ralf
authors.initials: R
authors.lastname: Bender
authors.forename: Thomas
authors.initials: T
authors.lastname: Kaiser
mesh_terms: D003198:Computer Simulation; D030881:Disclosure; D006801:Humans; D053208:Kaplan-Meier Estimate; D059012:Lost to Follow-Up; D015233:Models, Statistical; D016032:Randomized Controlled Trials as Topic; D016896:Treatment Outcome