The role of non-specific factors in treatment outcome of psychotherapy studies.

Non-specific factors refer to dimensions that are shared by most psychotherapies and include the therapeutic alliance, the therapist's competence and adherence to the treatment protocols whereas specific factors refer to the specific techniques and interventions that characterize particular psychotherapies. Review of the literature on non-specific treatment factors reveals that the therapeutic alliance and therapist competence may vary among patients and therapists, and that the therapeutic alliance also varies among treatment modalities. All three non-specific treatment factors, therapeutic alliance, therapist competence and adherence to the specific treatment modality, contribute significantly to treatment outcome and may account for more of the variance in outcome than specific treatment approach. Consequently, these factors need to be considered in the design of psychotherapy studies. In this paper we use the treatment study of infantile anorexia as an example of how to integrate these non-specific factors in the study design and the data analysis of treatment outcome in a psychotherapy study.