title: Prior elicitation and Bayesian analysis of the Steroids for Corneal Ulcers Trial.
abstract: OBJECTIVE
  To elicit expert opinion on the use of adjunctive corticosteroid therapy in bacterial corneal ulcers. To perform a Bayesian analysis of the Steroids for Corneal Ulcers Trial (SCUT), using expert opinion as a prior probability.
  
  
  METHODS
  The SCUT was a placebo-controlled trial assessing visual outcomes in patients receiving topical corticosteroids or placebo as adjunctive therapy for bacterial keratitis. Questionnaires were conducted at scientific meetings in India and North America to gauge expert consensus on the perceived benefit of corticosteroids as adjunct treatment. Bayesian analysis, using the questionnaire data as a prior probability and the primary outcome of SCUT as a likelihood, was performed. For comparison, an additional Bayesian analysis was performed using the results of the SCUT pilot study as a prior distribution.
  
  
  RESULTS
  Indian respondents believed there to be a 1.21 Snellen line improvement, and North American respondents believed there to be a 1.24 line improvement with corticosteroid therapy. The SCUT primary outcome found a non-significant 0.09 Snellen line benefit with corticosteroid treatment. The results of the Bayesian analysis estimated a slightly greater benefit than did the SCUT primary analysis (0.19 lines verses 0.09 lines).
  
  
  CONCLUSIONS
  Indian and North American experts had similar expectations on the effectiveness of corticosteroids in bacterial corneal ulcers; that corticosteroids would markedly improve visual outcomes. Bayesian analysis produced results very similar to those produced by the SCUT primary analysis. The similarity in result is likely due to the large sample size of SCUT and helps validate the results of SCUT.
authors.affiliation: FI Proctor Foundation, University of California, San Francisco, CA 94143-0412, USA.
authors.forename: Craig W
authors.initials: CW
authors.lastname: See
authors.forename: Muthiah
authors.initials: M
authors.lastname: Srinivasan
authors.forename: Somu
authors.initials: S
authors.lastname: Saravanan
authors.forename: Catherine E
authors.initials: CE
authors.lastname: Oldenburg
authors.forename: Elizabeth J
authors.initials: EJ
authors.lastname: Esterberg
authors.forename: Kathryn J
authors.initials: KJ
authors.lastname: Ray
authors.forename: Tanya S
authors.initials: TS
authors.lastname: Glaser
authors.forename: Elmer Y
authors.initials: EY
authors.lastname: Tu
authors.forename: Michael E
authors.initials: ME
authors.lastname: Zegans
authors.forename: Stephen D
authors.initials: SD
authors.lastname: McLeod
authors.forename: Nisha R
authors.initials: NR
authors.lastname: Acharya
authors.forename: Thomas M
authors.initials: TM
authors.lastname: Lietman
mesh_terms: D000287:Administration, Topical; D000890:Anti-Infective Agents / Q000627:therapeutic use; D001372:Aza Compounds / Q000627:therapeutic use; D001499:Bayes Theorem; D003320:Corneal Ulcer / Q000188:drug therapy* / Q000382:microbiology; D004311:Double-Blind Method; D015818:Eye Infections, Bacterial / Q000188:drug therapy* / Q000382:microbiology; D024841:Fluoroquinolones; D005938:Glucocorticoids / Q000627:therapeutic use*; D006801:Humans; D000077266:Moxifloxacin; D009883:Ophthalmic Solutions; D011239:Prednisolone / Q000031:analogs & derivatives* / Q000627:therapeutic use; D011804:Quinolines / Q000627:therapeutic use; D011795:Surveys and Questionnaires; D016896:Treatment Outcome; D014792:Visual Acuity / Q000187:drug effects*
chemical_list: D000890:Anti-Infective Agents; D001372:Aza Compounds; D024841:Fluoroquinolones; D005938:Glucocorticoids; D009883:Ophthalmic Solutions; D011804:Quinolines; C009022:prednisolone phosphate; D011239:Prednisolone; D000077266:Moxifloxacin