title: The Effects of Waiting for Treatment: A Meta-Analysis of Waitlist Control Groups in Randomized Controlled Trials for Social Anxiety Disorder.
abstract: Social anxiety disorder (SAD) is a highly prevalent mental disorder. However, little is known about how SAD changes in subjects who do not receive treatment. Waitlist control groups (WLCGs) are frequently included in randomized controlled trials (RCTs) on the treatment of mental disorders. Data from WLCGs are of value as they provide information on the untreated short-term course of a disorder and may serve as disorder-specific norms of change (benchmarks) against which treatment outcomes of SAD can be compared. Thus, we performed a meta-analysis focusing on the effects occurring in WLCGs of RCTs for SAD. Our study was conducted along the PRISMA guidelines. Thirty RCTs (total n = 2460) comprising 30 WLCGs and 47 treatment groups were included. Mean waiting time was 10.6 weeks. The pooled effect of waiting on SAD measures was g = 0.128 (95% CI: 0.057-0.199). Effects regarding other forms of anxiety, depression and functioning were of similarly small size. In contrast, change in the treatment groups was large, both within (g = 0.887) and between groups (g = 0.860). Our results show that for SAD, changes occurring in WLCGs of RCTs are small. The findings may serve as benchmarks in pilot studies of a new treatment or as an additional comparison in studies comparing two active treatments. For psychotherapy research in general, the small effect sizes found in WLCGs confirm that testing a treatment against a waiting list is not a very strict test. Further research on WLCGs in specific mental disorders is required, for example examining the expectancies of patients randomized to waiting. Copyright © 2016 John Wiley & Sons, Ltd.
  
  
  CONCLUSIONS
  In clinical practice, patients suffering from a mental disorder often have to wait for treatment. By analyzing data from waitlist control groups we can gain estimates of symptom change that occur during waiting. It could be seen that waiting for treatment only results in a negligible effect. Thus, in the short-term (i.e., 10.6 weeks) time is no healer in social anxiety disorder. Our results are similar to previous meta-analyses on the effects of waiting in other disorders, e.g., depression and posttraumatic stress disorder.
authors.affiliation: Clinic of Psychosomatic Medicine and Psychotherapy, University of Giessen, Giessen, Germany.
authors.forename: Christiane
authors.initials: C
authors.lastname: Steinert
authors.affiliation: Clinic of Psychosomatic Medicine and Psychotherapy, University of Giessen, Giessen, Germany.
authors.forename: Katja
authors.initials: K
authors.lastname: Stadter
authors.affiliation: Department of Psychotherapy and Systems Neuroscience, University of Giessen, Giessen, Germany.
authors.forename: Rudolf
authors.initials: R
authors.lastname: Stark
authors.affiliation: Clinic of Psychosomatic Medicine and Psychotherapy, University of Giessen, Giessen, Germany.
authors.forename: Falk
authors.initials: F
authors.lastname: Leichsenring
mesh_terms: D035061:Control Groups; D006801:Humans; D000072861:Phobia, Social / Q000628:therapy*; D011613:Psychotherapy / Q000379:methods*; D016032:Randomized Controlled Trials as Topic / Q000379:methods*; D016896:Treatment Outcome; D014850:Waiting Lists
keywords: Benchmarks; Meta-Analysis; Norms of Change; Social Anxiety Disorder; Waitlist Control Groups