LAUSR

OBJECTIVE This study examines the longitudinal impact of sudden gains/deteriorations across the outcomes associated with the phase model. METHOD In a sample of 16,657 clients who completed the Behavioral Health Measure-20, we identified sudden gains/deteriorations and employed multilevel piecewise analyses to assess their impact on subsequent treatment phases. RESULTS We found that: (1) Following a sudden gain in the well-being outcome, the mean-level for the symptom outcome increased (meaning symptoms improved), and the rate of change decreased, (2) Following a sudden gain in the symptom outcome, the mean-level for the life functioning outcome increased, (3) Following a sudden deterioration in the well-being outcome, the mean-level and rate of change for the symptom outcome decreased, and (4) Following a sudden deterioration in the symptom outcome, the mean-level for the life functioning outcome decreased. CONCLUSIONS These findings reveal that sudden gains/deteriorations function and occur at different rates across phases of change in psychotherapy.