262 audiotaped psychotherapy sessions from 81 individual therapies were rated completely on treatment adherence by independent blind raters using a newly developed rating manual. Different types of psychotherapy differed highly significantly in levels of treatment adherence, but treatment outcomes in either therapy approach was not predicted by level of therapists’ treatment adherence. Besides treatment adherence other nonspecific variables were investigated such as treatment alliance, therapists degree of professional experience, patients amount of psychological burden when they entered treatment, length of treatment and others.
Treatment adherence may play an indirect role with respect to treatment outcome when patients’ severity of psychological problems and its impact on the treatment alliance as well as therapists’ degree of professional experience are taken into account. The paper discusses the role of treatment fidelity in psychotherapy and the implications of this research and other recent meta-analyses with regard to the specifity versus nonspecifity debate in psychotherapy.