Review The effect of waiting: A meta-analysis of wait-list control groups in trials for tinnitus distress Hugo Hesser a, ⁎ , Cornelia Weise a , Winfried Rief b , Gerhard Andersson a,c a Department of Behavioural Sciences and Learning, Linnaeus Centre, Swedish Institute for Disability Research, Linköping University, Linköping, Sweden b Department of Clinical Psychology, University of Marburg, Marburg, Germany c Department of Clinical Neuroscience, Psychiatry Section, Karolinska Institutet, Stockholm, Sweden Received 3 September 2010; received in revised form 15 November 2010; accepted 14 December 2010 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. © 2011 Elsevier Inc. All rights reserved. Keywords: Tinnitus; Meta-analysis; Placebo effects; Wait-list group; Randomised controlled trial; Benchmark Introduction Tinnitus is an auditory disorder, defined as the perception of constant sound in ear(s) without any appropriate external source [1]. While tinnitus is a common condition affecting about 1 in 10 of the adult population [2,3], the majority of individuals with the condition do not consider tinnitus to be a serious health concern [4]. Yet, among those individuals who become preoccupied with the sensation, tinnitus is often associated with long-lasting problems, including anxiety, depression, insomnia and concentration difficulties [5,6]. Despite scientific advances in the field in recent years, tinnitus remains incurable in the majority of cases, as no underlying treatable ear disorder can be identified [1]. Given this, various forms of treatments have been developed with the purpose of providing relief for those with tinnitus by targeting the processes that are suggested to maintain or contribute to tinnitus distress [6–8]. In this domain, pharmacological, acoustic, complementary and psychological approaches have been proposed. Several of these diverse approaches to treatment have also been properly tested in controlled trials [9]. Unfortunately, the evidence does not provide an overall Journal of Psychosomatic Research 70 (2011) 378 – 384 ⁎ Corresponding author. Department of Behavioural Sciences and Learning, Linköping University, SE-581 83 Linköping, Sweden. Tel.: +46 13 28 58 45; fax: +46 13 28 21 45. E-mail address: hugo.hesser@liu.se (H. Hesser). 0022-3999/10/$ – see front matter © 2011 Elsevier Inc. All rights reserved. doi:10.1016/j.jpsychores.2010.12.006