title: Comparison of noninferiority margins reported in protocols and publications showed incomplete and inconsistent reporting.
abstract: OBJECTIVE
  To compare noninferiority margins defined in study protocols and trial registry records with margins reported in subsequent publications.
  
  
  METHODS
  Comparison of protocols of noninferiority trials submitted 2001 to 2005 to ethics committees in Switzerland and The Netherlands with corresponding publications and registry records. We searched MEDLINE via PubMed, the Cochrane Controlled Trials Register (Cochrane Library issue 01/2012), and Google Scholar in September 2013 to identify published reports, and the International Clinical Trials Registry Platform of the World Health Organization in March 2013 to identify registry records. Two readers recorded the noninferiority margin and other data using a standardized data-abstraction form.
  
  
  RESULTS
  The margin was identical in study protocol and publication in 43 (80%) of 54 pairs of study protocols and articles. In the remaining pairs, reporting was inconsistent (five pairs, 9%), or the noninferiority margin was either not reported in the publication (five pairs, 9%) or not defined in the study protocol (one pair). The confidence interval or the exact P-value required to judge whether the result was compatible with noninferior, inferior, or superior efficacy was reported in 43 (80%) publications. Complete and consistent reporting of both noninferiority margin and confidence interval (or exact P-value) was present in 39 (72%) protocol-publication pairs. Twenty-nine trials (54%) were registered in trial registries, but only one registry record included the noninferiority margin.
  
  
  CONCLUSIONS
  The reporting of noninferiority margins was incomplete and inconsistent with study protocols in a substantial proportion of published trials, and margins were rarely reported in trial registries.
authors.affiliation: Department of Clinical Epidemiology, Leiden University Medical Center, The Netherlands.
authors.forename: Olaf M
authors.initials: OM
authors.lastname: Dekkers
authors.affiliation: Institute of Social & Preventive Medicine (ISPM), University of Bern, Finkenhubelweg 11, CH-3012, Switzerland; CTU Bern, Department of Clinical Research, University of Bern, 3012 Bern, Switzerland.
authors.forename: Myriam
authors.initials: M
authors.lastname: Cevallos
authors.affiliation: Institute of Social & Preventive Medicine (ISPM), University of Bern, Finkenhubelweg 11, CH-3012, Switzerland.
authors.forename: Jonas
authors.initials: J
authors.lastname: Bührer
authors.affiliation: Division of Clinical Epidemiology, University Hospitals of Geneva, Geneva, Switzerland.
authors.forename: Antoine
authors.initials: A
authors.lastname: Poncet
authors.affiliation: Institute of Social & Preventive Medicine (ISPM), University of Bern, Finkenhubelweg 11, CH-3012, Switzerland.
authors.forename: Sabine
authors.initials: S
authors.lastname: Ackermann Rau
authors.affiliation: Division of Clinical Epidemiology, University Hospitals of Geneva, Geneva, Switzerland.
authors.forename: Thomas V
authors.initials: TV
authors.lastname: Perneger
authors.affiliation: Institute of Social & Preventive Medicine (ISPM), University of Bern, Finkenhubelweg 11, CH-3012, Switzerland; Centre for Infectious Disease Epidemiology and Research (CIDER), University of Cape Town, South Africa. Electronic address: egger@ispm.unibe.ch.
authors.forename: Matthias
authors.initials: M
authors.lastname: Egger
mesh_terms: D002985:Clinical Protocols / Q000592:standards*; D016001:Confidence Intervals; D009426:Netherlands; D011642:Publications; D016032:Randomized Controlled Trials as Topic / Q000592:standards*; D012042:Registries; D012107:Research Design / Q000592:standards*; D013557:Switzerland
keywords: Completeness of reporting; Journal publications; Noninferiority margin; Noninferiority trials; Study protocols; Trial registration