An Exploration of Sudden Gains in Psychotherapy

Objectives: The aims of this review were to investigate how the criteria used to identify sudden gains (SGs) have been adapted, and what impact these adaptations have on the association between treatment outcomes and SGs.
Methods: A systematic review of the literature was conducted followed by data extraction, quality assessment, and a meta-analysis, with two subgroup analyses.
Results: A total of 17 papers were identified, which included three adapted SGs criteria. 15 adapted SGs criteria were identified, however the majority could not be included due to being used in fewer than three studies. Quality appraisal found the studies to be of moderate to low quality. The meta-analysis found a significant difference in outcomes between SG and non-SG groups, with an effect size of g = .51. Subgroup analysis between the SGs criteria found that the combined Tang and Gaynor criteria had an effect size of g = .94, whereas the Hardy and Kelly criteria had effect sizes of g = .42 and g = .39 respectively.
Conclusions: The extent of the adaptations to the SGs criteria is potentially reducing the validity of SGs research. The differences between the criteria need to be understood further. A strength of the combined Tang and Gaynor criteria may be its strictness combined with its ability to identify early SGs, which creates a good association with treatment outcomes. Moving forwards, SGs research must consider how the SG criteria can be applied in a clinical setting to support the improved treatment outcomes related to SGs.