An approach to psychotherapy toleration: the Distress/Endorsement Validation Scale (DEVS) for clinical outcome studies.

The issue of treatment tolerance within the field of psychotherapy is, at best, a nebulous construct and has been commonly evaluated via rates of subject attrition and homework compliance. This research presents the psychometric properties of a ten-item scale which endeavours to measure treatment distress and participant endorsement of therapy protocols used in clinical research. Two factors emerged and the subscales of Distress and Endorsement were derived. These subscales displayed good reliability with acceptable inter-item correlations within each subscale. The subscales were also able to differentiate the perspectives of male Vietnam veterans from their spouses on a lifestyle management course at the termination of intervention. However, this scale also displayed a cognitive behavioural trauma treatment protocol and eye movement desensitisation and reprocessing to be equivalent in treatment distress and participant endorsement in the treatment of post-traumatic stress disorder. Preliminary findings suggest that the relationship between these two subscales and outcome may, to some extent, be population specific. First evidence suggests that intervention distress ratings may be influenced by severity of presentation, whilst endorsement ratings are more influenced by symptomatic improvement over time. Suggestions for future research are presented and the full questionnaire is attached as an appendix.