Group cognitive-behavioural therapy for hoarding disorder: Systematic review and meta-analysis.

Previous meta-analysis has reported the rate of reliable and clinically significant changes in hoarding disorder (HD) after cognitive-behavioural therapy (CBT) based on the classical CBT model of HD, as between 42% and 25%. However, in this analysis, different types of therapy (group vs individual, G-CBT and I-CBT, respectively), different providers (psychologist vs nonpsychologist), and different diagnosis (HD vs hoarding behaviour) were analysed together. Hence, it remains unclear if reported rate of changes was due to limits of the CBT model of HD or due to the fact that different applications of the model were analysed together. The aim of this meta-analysis is to highlight shortcomings in the description of existing approaches in G-CBT in HD and provide an up-to-date review of the current state of efficacy. We searched references for treatment trials of G-CBT for HD in adults with object hoarding, where treatment was conducted by a professional in PubMed, PsychINFO and Web of Science databases, and ResearchGate (for grey literature). Data on participants, treatment modalities, and outcomes were extracted; treatment effect-size was meta-analysed. Five hundred and forty-three references were found; after title and abstract screening, eight articles (178 participants) were retained of which seven were included in the meta-analysis. G-CBT showed improvement of HD severity at posttreatment (Hedge's g = 0.96). The rate of clinically reliable changes across groups of treatment was 21%-68% (M = 36.7%; SD = 12.1%). The meta-analyses showed a statistically but not clinically significant impact of age on effect-size. No publication bias was found. There is strong evidence supporting the efficacy of G-CBT including modified or extended versions of classical G-CBT protocols. However, controlled trials with follow-up assessment are needed to evaluate long-term G-CBT efficacy for HD. As well, the rate of clinically significant changes is low; further research on the HD model could improve the efficacy of G-CBT.