Assessing decision-making capacity at end of life

Patients with terminal illness often face important medical decisions that may carry ethical and legal implications, yet they may be at increased risk for impaired decisional capacity. This study examined the prevalence of impairment on the four domains of decisional capacity relevant to existing legal standards.

Twenty-four adults diagnosed with a terminal illness completed the MacArthur Competence Assessment Tool for Treatment, a semi-structured measure of decision-making capacity and measures of cognitive functioning and psychological distress.

Approximately one third of the sample demonstrated serious impairment on at least one domain of decisional capacity. The greatest proportion of impairment was found on subscales that rely heavily on verbal abilities. Decisional capacity was significantly associated with cognitive functioning and education, but not with symptoms of anxiety or depression.

This study is the first to examine decisional capacity in patients with terminal illness relative to legal standards of competence. Although not universal, decisional impairment was common. Clinicians working with terminally ill patients should frequently assess capacity as these individuals are called on to make important medical decisions. Comprehensive assessment will aid clinicians in their responsibility to balance respect for patient autonomy with their responsibility to protect patients from harm resulting from impaired decisional capacity.