Patterns of symptomology over time and their relation to outcome

The purpose of this study was to examine the association between characteristics of the symptomatology change curve (i.e., initial symptomatology, rate of change, curvature) and final treatment outcome. The sample consisted of community clients (N = 492) seen by 204 student therapists at a training clinic. A multilevel approach to account for therapist effects was followed. Linear, quadratic, and cubic trajectories of anxiety and depression symptomatology, as assessed by the Shorter Psychotherapy and Counseling Evaluation (sPaCE; Halstead, Leach, & Rust, 2007), were estimated. The multilevel quadratic trajectory best fit the data and depicted a descending curve (partial “U”-shaped). The quadratic growth parameters (intercept, slope, quadratic) were then used as predictors of both symptom change and reliable improvement in general symptomatology (pre- to post-treatment), as assessed by the Outcome Questionnaire-45.2 (OQ-45.2; Lambert, Hansen, Umpress, Lunen, Okiishi et al., 1996). The quadratic growth parameters of depression and anxiety showed predictive power for both symptom change and reliable improvement in general symptomatology. Patterns for two different successful outcomes (1-change in general symptomatology and 2-reliable improvement) were identified. For symptom change, successful outcomes followed a pattern of low initial levels of depression and anxiety, high initial rates of change (slope), and high (flattening after initial drop) curvature, and the pattern applied to both within- and between-therapist levels. For reliable improvement at within-therapist level, successful outcomes followed a pattern of high initial rate of change (slope) and high curvature. For reliable improvement at between-therapist level, successful outcomes were associated with a pattern of low initial levels of depression and anxiety. Implications for clinical practice are discussed.