Interpersonal problems and outcome in outpatient psychotherapy: findings from a long-term longitudinal study in Germany.

We used a comprehensive longitudinal data set from Germany to examine trajectories of symptom distress depending on interpersonal problems at study intake measured via the Inventory of Interpersonal Problems-64 (IIP-64; Horowitz, Strau, & Kordy, 1994). Participants (N=622) underwent mid- or long-term outpatient psychotherapy (either psychodynamically oriented psychotherapy, cognitive behavioral therapy, or analytic psychotherapy). Data comprises up to 5 assessments during a 2-year period and was analyzed via hierarchical linear modeling. In the analytic psychotherapy subgroup, initial symptom level was higher in submissive patients. Initial interpersonal problems were not predictive of the rate of symptom change during therapy. Only in psychodynamic treatments, low affiliation positively affected treatment outcome. Interpersonal problems at intake were not related to the number of utilized sessions and utilization rate across treatment subgroups. We discuss the findings and outline future research topics.