Reliability of mental capacity assessments in psychiatric in-patients

Abstract

Background: Previous work on the reliability of mental capacity assessments in patients with psychiatric illness has been limited.Aims: To describe the interrater reliability of two independent assessments of capacity to consent to treatment, as well as assessments made by a panel of clinicians based on the same interview.Method: Fifty-five patients were interviewed by two interviewers 1–7 days apart and a binary (yes/no) capacity judgement was made, guided by the MacArthur Competence Assessment Tool for Treatment (MacCAT-T). Four senior clinicians used transcripts of the interviews to judge capacity.Results: There was excellent agreement between the two interviewers for capacity judgements made at separate interviews (kappa=0.82). A high level of agreement was seen between senior clinicians for capacity judgements of the same interview (mean kappa=0.84)Conclusions: In combination with a clinical interview, the MacCAT–T can be used to produce highly reliable judgements of capacity.