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. Conclusion 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.