Abstract

Background There is a need for a measure to evaluate change in treatment for offenders with a personality disorder, and the Progress Rating Scale (PRS) was developed to meet this need taking account of multiprofessional input. Method The PRS comprises six process and five non-process items developed via thematic analysis of routine CPA patient treatment reports at a forensic Personality Disorder Service. Rating for items was fully standardized and operationalized with revisions aiming to maximize inter-rater agreement reflecting good face and content validity. Psychometric properties were examined using PRS ratings for 147 patients at three different time points in conjunction with relevant psychometrics. Results Following refinement, the instrument demonstrated good content validity. Intra-class correlations suggested moderate to substantial inter-rater agreement (intraclass correlations: 0.63–0.92). Item analyses indicated good internal consistency for process items (Cronbach's alpha: 0.82–0.88). Correlations with relevant psychometrics revealed meaningful relationships between PRS scores, defence styles and social problem solving. PRS score trajectories were in line with previously known treatment outcomes supporting predictive validity. Conclusion The PRS shows promise as process measure in clinical settings but requires further testing on other samples to confirm initial findings and demonstrate its utility.