Psychiatric Illness and Medical Decision-Making Capacity: A Retrospective Study in Medical Settings

Determination of medical decision-making capacity (DMC) is one of the common encounters in Consultation-Liaison Psychiatry (CLP) services. It is a common misbelief that patients with “psych history” lack capacity more often than patients without mental illness. The study aims to examine the relationship between mental illness and DMC in patients presented to acute medical settings. The study is a retrospective chart review, where data were collected from the patients admitted to the medical units and assessed for capacity by a psychiatrist. Clinical and demographic characteristics were compared between two groups (patients having capacity and lacking capacity) using t-tests or chi-square tests, as appropriate. The commonest reason for DMC evaluation requests was for the patients who wanted to leave the hospital against medical advice. Overall, 53% (52/98) of the patients evaluated for DMC were found to lack capacity. Group of patients lacking DMC had a significantly higher percentage of males (58% vs. 35%) but were significantly less employed (8% vs. 10%). No significant difference was observed in other demographic characteristics and primary psychiatric diagnoses (past and current) among the two groups. However, patients lacking capacity were found to have a significantly more occurrence of current (48% vs. 11%) and past (23% vs. 4%) history of neurocognitive disorder, and larger trend significance (31% vs. 15%) of active psychiatric symptoms. We conclude that patients with neurocognitive disorders and active psychiatric symptoms might have poor DMC but not all patients who have psychiatric diagnoses lack medical DMC. Larger studies especially in outpatient psychiatric settings are suggested to derive more conclusive results.