Objectives: The aim of this study was to advance understanding of stage of illness in bipolar disorder (BD), by interrogating the literature for evidence of an influence of stage of illness on functional (ie non-symptom) outcomes following psychosocial intervention.
Methods: A systematic literature search following PRISMA guidelines was conducted to identify empirical studies of psychosocial interventions for established BD. To investigate stage as a predictor of three functional outcomes (general/social functioning, cognitive functioning and quality of life [QoL]), study samples were dichotomised into earlier and later stage using proxy measures identified in existing staging models. Findings were integrated using data-based convergent synthesis.
Results: A total of 88 analyses from 62 studies were identified. Synthesis across studies suggested that psychosocial intervention was more likely to be effective for general functioning outcomes earlier in the course of established BD. No stage-related differences were found for cognitive or QoL outcomes. Exploratory investigations found some evidence of an interaction between specific intervention type and stage of illness in predicting outcomes.
Conclusions: A novel systematic review provided preliminary evidence that benefits general/social functioning may be more pronounced in earlier versus later stages of established BD. The review also generated hypotheses about a potential three-way interaction, whereby specific psychosocial interventions may be best placed to target functional outcomes in earlier versus later stage BD. The strength of conclusions is limited by the overall low-quality and significant heterogeneity of studies. Further research is urgently required to understand the impact of illness stage on the effectiveness of psychosocial interventions.
Keywords: bipolar disorder; bipolar disorder/psychology; psychotherapy; social functioning; staging models; treatment outcomes.
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