title: The influence of industry sponsorship on the reporting of subgroup analyses within phase III randomised controlled trials in gastrointestinal oncology.
abstract: OBJECTIVE
  Correct interpretation of subgroup analyses (SGA) is important as it influences selection of therapeutic interventions for patient subsets. The primary aim of our study was to compare reporting of SGA between industry and non-industry sponsored trials.
  
  
  METHODS
  We performed a systematic literature review and extracted data from journal articles (JA) and conference abstracts (CA) published over a decade reporting SGA results of phase III randomised controlled gastrointestinal (GI) oncology trials with patient participants of ≥150.
  
  
  RESULTS
  In JA, SGA was reported in 100/145 (69%) trials: 41/54 industry sponsored (76%; 95% confidence interval [CI]: 63-86%) and 59/91 non-industry sponsored (65%; 95% CI: 55-74%) trials (p = 0.16). In CA, SGA was reported in 86/204 (42%) trials: 43/83 industry sponsored (52%; 95% CI: 41-62%) and 43/121 non-industry sponsored (36%; 95% CI: 28-44%) trials (p = 0.02). Number of SGA performed per trial was significantly larger for industry compared to non-industry sponsored trials in both JA (median 6 versus 2, p = 0.003) and CA (median 1 versus 0, p = 0.023). Claims of subgroup effect were made in 52% of trials in JA and 50% in CA, with significant test of interaction evident in only 25% of JA and 16% of CA, with no difference between industry and non-industry trials. Industry sponsored trials with a significant primary end-point reported more SGA (p < 0.001 JA; p = 0.046 CA).
  
  
  CONCLUSIONS
  Industry sponsored trials reported more SGA. Claimed subgroup effects were often not accompanied by significant interaction test; thus circumspection should be adopted when using SGA to deviate from standard therapeutic decision-making in GI oncology.
authors.affiliation: Department of Medicine, Royal Marsden Hospital, London & Surrey, UK.
authors.forename: Sarah
authors.initials: S
authors.lastname: Barton
authors.affiliation: Department of Clinical Research and Development, Royal Marsden Hospital, Surrey, UK.
authors.forename: Clare
authors.initials: C
authors.lastname: Peckitt
authors.affiliation: Department of Medicine, Royal Marsden Hospital, London & Surrey, UK.
authors.forename: Francesco
authors.initials: F
authors.lastname: Sclafani
authors.affiliation: Department of Medicine, Royal Marsden Hospital, London & Surrey, UK.
authors.forename: David
authors.initials: D
authors.lastname: Cunningham
authors.affiliation: Department of Medicine, Royal Marsden Hospital, London & Surrey, UK. Electronic address: ian.chau@rmh.nhs.uk.
authors.forename: Ian
authors.initials: I
authors.lastname: Chau
mesh_terms: D017326:Clinical Trials, Phase III as Topic / Q000191:economics* / Q000379:methods / Q000706:statistics & numerical data; D003627:Data Interpretation, Statistical; D004345:Drug Industry / Q000191:economics*; D005762:Gastroenterology / Q000191:economics* / Q000379:methods / Q000706:statistics & numerical data; D005770:Gastrointestinal Neoplasms / Q000473:pathology / Q000628:therapy*; D006801:Humans; D008495:Medical Oncology / Q000191:economics* / Q000379:methods / Q000706:statistics & numerical data; D016032:Randomized Controlled Trials as Topic / Q000191:economics* / Q000379:methods / Q000706:statistics & numerical data; D012107:Research Design / Q000706:statistics & numerical data; D058028:Research Report; D012109:Research Support as Topic / Q000191:economics*; D018401:Sample Size; D016896:Treatment Outcome
keywords: Gastrointestinal cancer; Industry sponsorship; Randomised controlled trial; Subgroup analysis