The Impact of Sudden Gains and Deteriorations on the Psychotherapy Process

Within the field of psychotherapy research, there has been significant evidence to suggest that people change and improve because of treatment (Lambert & Ogles, 2004). One common phenomenon that has been observed when looking more closely at outcome trajectories has been termed sudden gains/deteriorations. These are defined as sudden changes in outcome (either positive or negative) of 25% or more from the pre-change level of symptoms that are in turn sustained over time (Tang & DeRubeis, 1999). Although there are data regarding how people who experience sudden gains end up after treatment, no studies have examined the impact that sudden gains and deteriorations have more immediately on related outcome domains. The phase model of change in psychotherapy describes three sequential stages of improvement which occur over the course of successful treatment ((1) the client acquires a greater sense of well-being, (2) symptoms associated with diagnoses diminish, and (3) functioning in work, relationships, and self-care improves ) (Howard, Lueger, Maling, & Martinovich, 1993; Kopta, Owen, & Budge, 2015, p. 442). Although there is support in the research for each latter phase being contingent on the improvement of those that occur prior (Kopta, Owen, & Budge, 2015), the relationship between sudden gains and deteriorations on these various outcome domains has not been tested. The present study utilized a sample of 16,657 clients who engaged in routine psychotherapy and completed the Behavioral Health Measure-20 before every session. This measure is comprised of three scales that correspond directly with the components of the phase model (Kopta, Owen, & Budge, 2015). Among clients who experienced sudden gains or deteriorations on BHM-20 scales, multilevel piecewise analyses were used to assess if following a sudden gain or deterioration in one phase, clients experienced change in level and/or slope for the outcome associated with the subsequent phase. We found that: (1) Following a sudden gain in well-being, the mean-level for symptoms increased significantly, and the rate of change decreased significantly, (2) Following a sudden gain in symptoms, the mean-level for life functioning increased significantly, (3) Following a sudden deterioration in well-being, the mean-level and rate of change for symptoms both decreased significantly, and (4) Following a sudden deterioration in symptoms, the mean-level for life functioning decreased significantly. This series of analyses represented the first true test of the impact of sudden gains and deteriorations on clients as they continue to participate in the therapy process and of the relationships between the trajectories of change associated with the phase model