Decision-making capacity for treatment in psychiatric and medical in-patients: Cross-sectional, comparative study

<jats:sec><jats:title>Background</jats:title><jats:p>Is the nature of decision-making capacity (DMC) for treatment significantly different in medical and psychiatric patients?</jats:p></jats:sec><jats:sec><jats:title>Aims</jats:title><jats:p>To compare the abilities relevant to DMC for treatment in medical and psychiatric patients who are able to communicate a treatment choice.</jats:p></jats:sec><jats:sec><jats:title>Method</jats:title><jats:p>A secondary analysis of two cross-sectional studies of consecutive admissions: 125 to a psychiatric hospital and 164 to a medical hospital. The MacArthur Competence Assessment Tool – Treatment and a clinical interview were used to assess decision-making abilities (understanding, appreciating and reasoning) and judgements of DMC. We limited analysis to patients able to express a choice about treatment and stratified the analysis by low and high understanding ability.</jats:p></jats:sec><jats:sec><jats:title>Results</jats:title><jats:p>Most people scoring low on understanding were judged to lack DMC and there was no difference by hospital (<jats:italic>P</jats:italic>=0.14). In both hospitals there were patients who were able to understand yet lacked DMC (39% psychiatric<jats:italic>v.</jats:italic>13% medical in-patients,<jats:italic>P</jats:italic>&lt;0.001). Appreciation was a better ‘test’ of DMC in the psychiatric hospital (where psychotic and severe affective disorders predominated) (<jats:italic>P</jats:italic>&lt;0.001), whereas reasoning was a better test of DMC in the medical hospital (where cognitive impairment was common) (<jats:italic>P</jats:italic>=0.02).</jats:p></jats:sec><jats:sec><jats:title>Conclusions</jats:title><jats:p>Among those with good understanding, the appreciation ability had more salience to DMC for treatment in a psychiatric setting and the reasoning ability had more salience in a medical setting.</jats:p></jats:sec>