title: Effectiveness of blinding: sham suprapubic incisions in a randomized trial of retropubic midurethral sling in women undergoing vaginal prolapse surgery.
abstract: OBJECTIVE
  This planned secondary analysis of the Outcomes Following Vaginal Prolapse Repairs and Midurethral Sling trial assessed whether treatment knowledge differed between randomized groups at 12 months and whether treatment success was affected by treatment perception.
  
  
  METHODS
  Sham suprapubic tension-free vaginal tape (TVT) incisions were made in the Outcomes Following Vaginal Prolapse Repairs and Midurethral Sling trial participants randomized to no-TVT. Primary surgical outcomes and maintenance of blinding was assessed at 12 months. Knowledge of treatment assignment was compared between groups, and the relationship with treatment success rates was assessed.
  
  
  RESULTS
  Prior to the 12 month postoperative visit, only 4% of treated participants (13 of 336) formally reported unmasking. At 12 months, 94% of the randomized participants (315 of 336) provided treatment knowledge data. Sixteen TVT participants (10%) reported treatment knowledge; most (n = 15, 94%) were correct; 17 of the sham participants (11%) reported treatment knowledge; half (n = 8, 47%) were correct. Similar proportions of unmasked participants who reported no treatment knowledge correctly guessed/perceived treatment assignment (sham, 46 [33%] vs TVT, 44 [33%]). We did not detect significant differences in treatment success rates based on perception within and across received treatment groups (perceived sham vs TVT overall [P = .76]). Of those receiving TVT, more participants perceiving TVT had treatment success compared with those who perceived sham (84% vs 74%; P = .29). Among sham participants, more participants perceiving sham had success compared with those who perceived receiving TVT (65% vs 56%; P = .42).
  
  
  CONCLUSIONS
  Sham surgical incisions effectively mask TVT randomization. These findings may help to inform future surgical trial designs.
authors.affiliation: Departments of Obstetrics and Gynecology and Urology, Stritch School of Medicine, Loyola University Chicago, Chicago, IL. Electronic address: LBrubaker@lumc.edu.
authors.forename: Linda
authors.initials: L
authors.lastname: Brubaker
authors.affiliation: Department of Reproductive Medicine, University of California, San Diego, School of Medicine, San Diego, CA.
authors.forename: Charles W
authors.initials: CW
authors.lastname: Nager
authors.affiliation: Department of Obstetrics and Gynecology, University of Alabama at Birmingham School of Medicine, Birmingham, AL.
authors.forename: Holly E
authors.initials: HE
authors.lastname: Richter
authors.affiliation: Department of Obstetrics and Gynecology, Duke University Medical Center, Durham, NC.
authors.forename: Alison C
authors.initials: AC
authors.lastname: Weidner
authors.affiliation: Department of Obstetrics and Gynecology, University of Utah School of Medicine, Salt Lake City, UT.
authors.forename: Yvonne
authors.initials: Y
authors.lastname: Hsu
authors.affiliation: Department of Obstetrics and Gynecology, University of Texas Southwestern Medical Center at Dallas, Dallas, TX.
authors.forename: Clifford Y
authors.initials: CY
authors.lastname: Wai
authors.affiliation: Ob/Gyn and Women's Health Institute, Cleveland Clinic, Cleveland, OH.
authors.forename: Marie
authors.initials: M
authors.lastname: Paraiso
authors.affiliation: RTI International, Research Triangle Park, NC.
authors.forename: Tracy L
authors.initials: TL
authors.lastname: Nolen
authors.affiliation: RTI International, Research Triangle Park, NC.
authors.forename: Dennis
authors.initials: D
authors.lastname: Wallace
authors.affiliation: Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD.
authors.forename: Susan
authors.initials: S
authors.lastname: Meikle
mesh_terms: D005260:Female; D006801:Humans; D016015:Logistic Models; D010465:Perception; D015990:Placebo Effect; D010919:Placebos; D016032:Randomized Controlled Trials as Topic; D053825:Suburethral Slings; D016896:Treatment Outcome; D014550:Urinary Incontinence, Stress / Q000601:surgery*; D014596:Uterine Prolapse / Q000601:surgery*
chemical_list: D010919:Placebos
keywords: pelvic organ prolapse; sham incision; stress urinary incontinence; surgical trial