Prior research has established that common therapeutic relationship factors are potent predictors of change in psychotherapy, but such factors are typically studied one at a time and their underlying structure when studied simultaneously is not clear. We assembled empirically validated relationship factors (e.g., therapist empathy; patient expectations; agreement about goals) into a single instrument and subjected it to factor analysis. Method: The instrument was applied to patients (N = 332) undergoing intensive psychotherapy of different types for depressive disorders, anxiety disorders, eating disorders, and childhood trauma in an inpatient specialized mental health setting. In order to examine the psychometric properties of the scale, we used half the sample (N=164) to conduct exploratory factor analysis (EFA) and parallel analysis before we tested the solution using exploratory structural equation modeling (ESEM) on the second half of the sample (N=168). Measurement invariance analysis was conducted to examine the stability of the factor structure. Results: The analysis yielded two factors, which were termed 1. "Confidence in the therapist" and 2. "Confidence in the treatment." Discussion: When assessed simultaneously, patients differentiate between their evaluation of the therapist and of the treatment. The results indicate that there is substantial overlap among previously established relationship factors. Trial registration: ClinicalTrials.gov identifier: NCT03503981.

Previous research suggests that common relationship factors are composed of two overarching factors, "Confidence in the therapist" and "Confidence in the treatment." The aim of this naturalistic processoutcome study was to investigate the reciprocal relationships between these two constructs and patients' symptom level across treatment. The sample consisted of 587 patients who were admitted to an inpatient program and treated with psychotherapy for a range of mental health disorders, such as chronic depression, anxiety disorders, and eating disorders. Our data consisted of weekly measures of symptomatic distress (Patient Health Questionnaire) and the common relationship factors were measured weekly using a newly developed scale. Latent curve modeling with structured residuals was used to investigate the between-and within effects of week-to-week changes in the two components as predictors of subsequent symptom level. An increase in both relationship factors predicted a decrease in subsequent levels of symptoms at the withinpatient level, and the other way around, but the two relationship factors did not systematically relate to one another at the within-patient level over the course of treatment. Our findings indicate that patients' perceptions of the therapist as a person and their appraisal of the treatment, are important, different predictors of therapeutic change. Furthermore, they support prior research demonstrating a reciprocal relationship between common relationship factors and symptomatic distress and add to existing common factor theory by exploring the role of two central relationship dimensions and using a method which examines reciprocal relationships and within-patient effects simultaneously. Public Significance StatementThis study suggests that patients' appraisal of their confidence in the therapist and confidence in the treatment contributes to psychotherapeutic change above and beyond early symptom change. Thus, patients' perception of the therapist as a person, and patients' perceptions of the treatment, is important, different predictors of therapeutic change.