Agreement over content of case formulation in offender personality disorder pathway prison services

Case formulation plays a key role in effective management of offenders' needs, particularly on the Offender Personality Disorder Pathway (OPDP).

To validate a method of investigating formulations with offenders still in prison but in the OPD Pathway and investigate agreement over the content of formulations between each of the main dyadic pairs: offender-clinician, offender-key worker and clinician-key worker.

We developed a checklist of the main features of a formulation from a review of initial formulations in the files of prisoners in two prisons which operate within the OPD Pathway system. We then recruited 30 violent offenders in each OPD wing of two prisons, and asked each of them, their clinically qualified worker (usually a psychologist) and the criminal justice system key worker to complete a formulation summary according to a card-sort process based on this checklist. We calculated the level of agreement between pairs of raters (e.g. offender and key worker) about the importance of aspects of each domain to the case using intraclass correlation coefficients.

The rating tool showed good internal validity. Analysis of inter-rater ratings showed agreement among teams on aspects relating to prisoners' observable actions, experiences and external support domains, but little agreement on cognitions, feelings, risky situations or staff/self-support, mainly affecting the prisoner-key worker dyad. There were, however, significant differences in agreement rates between the two sites.

Agreement within teams about formulations is strong where content relates to overt behaviours and points of fact, but weaker on risk, cognitions and support. The appropriateness of this approach to formulation across cultural groups may need further evaluation as the main measured difference between the prisons was in distribution of ethnic and cultural groups.