title: The effect of waiting: A meta-analysis of wait-list control groups in trials for tinnitus distress.
abstract: OBJECTIVE
  The response rates and effects of being placed on a wait-list control condition are well documented in psychiatric populations. Despite the usefulness of such estimates and the frequent use of no-treatment controls in clinical trials for tinnitus, the effect of waiting in a tinnitus trial has not been investigated systematically. The aim of the present study was to quantify the overall effect of wait-list control groups on tinnitus distress.
  
  
  METHODS
  Studies were retrieved via a systematic review of randomised controlled trials of cognitive behaviour therapy for tinnitus distress. Outcomes of psychometrically robust tinnitus-specific measures (Tinnitus Handicap Inventory, Tinnitus Questionnaire, Tinnitus Reaction Questionnaire) from wait-list control groups were quantified using meta-analytic techniques. Percentage of change and standard mean difference effect sizes were calculated using the pre and post wait period.
  
  
  RESULTS
  Eleven studies involving 314 wait-list subjects with tinnitus were located. The analysis for a waiting period of 6 to 12 weeks revealed a mean decrease in scores on tinnitus-specific measures of 3% to 8%. Across studies, a statically significant small mean within-group effect size was obtained (Hedges' g=.17). The effects were moderated by methodological quality of the trial, sample characteristics (i.e., age, tinnitus duration), time of the wait-list and how diagnosis was established.
  
  
  CONCLUSIONS
  Subjects in a tinnitus trial improve in tinnitus distress over a short waiting phase. The effects of waiting are highly variable and depend on the characteristics of the sample and of the trial.
authors.affiliation: Department of Behavioural Sciences and Learning, Linnaeus Centre, Swedish Institute for Disability Research, Linköping University, Linköping, Sweden. hugo.hesser@liu.se
authors.forename: Hugo
authors.initials: H
authors.lastname: Hesser
authors.forename: Cornelia
authors.initials: C
authors.lastname: Weise
authors.forename: Winfried
authors.initials: W
authors.lastname: Rief
authors.forename: Gerhard
authors.initials: G
authors.lastname: Andersson
mesh_terms: D002986:Clinical Trials as Topic; D035061:Control Groups; D006801:Humans; D015990:Placebo Effect; D012107:Research Design; D014012:Tinnitus / Q000523:psychology*; D014850:Waiting Lists