Assessing the clinical significance of treatment outcomes for distressing voices in routine clinical practice.

Determining reliable and clinically significant change is central to evidence-based practice yet rarely used in routine clinical settings. This paper illustrates these methods in the context of an evaluation of cognitive behaviour therapy for distressing auditory hallucinations ("voices"). We used data from a clinical sample attending Perth Voices Clinic, a transdiagnostic outpatient service for distressing voices, and a previously published reference sample of healthy voice hearers. Our outcomes on the primary measure of voice distress, derived from a previous factor analysis of the Psychotic Symptom Rating Scale-Auditory Hallucinations subscale, showed that 62.9% of clients were classified as Recovered/Improved, 35.5% were classified as Unchanged, and 0.02% were classified as Deteriorated. Partial support for the validity of these classifications was obtained from the scores on the Depression, Anxiety, Stress Scales (Lovibond & Lovibond, 1995) but not on the Social and Occupational Functional Assessment Scale (Goldman et al., 1992). Clients classified as Recovered showed better emotional functioning on the Depression, Anxiety, Stress Scales compared with those who did not make a clinically significant change in voice distress. A tool is provided to assist practitioners to evaluate whether individual clients have benefited from therapy for distressing voices or not, which can be used to guide future treatment decisions (https://osf.io/gd9e5/).