Received 3 September 2010;
revised 15 November 2010;
accepted 14 December 2010.
ObjectiveThe 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.
MethodsStudies 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.
ResultsEleven 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.
ConclusionSubjects 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.
Keywords: Tinnitus; Meta-analysis; Placebo effects; Wait-list group; Randomised controlled trial; Benchmark