Assessing the Decision-Making Capacity of Terminally Ill Patients with Cancer.

Objective: Despite the clinical, ethical, and legal magnitude of end-of-life decision-making, the capacity of terminally ill patients to make the medical decisions they often face is largely unknown. In practice, clinicians are responsible for determining when their patients are no longer competent to make treatment decisions, yet the accuracy of these assessments is unclear. The purpose of this study was to explore decision-making capacity and its assessment in terminally ill cancer patients.

Methods: Fifty-five patients with advanced cancer receiving inpatient palliative care and 50 healthy adults were administered the MacArthur Competence Assessment Tool for Treatment (MacCAT-T) to evaluate decision-making capacity with regard to the four most commonly used legal standards: Choice, Understanding, Appreciation, and Reasoning. Participants made a hypothetical treatment decision about whether to accept artificial nutrition and hydration for treatment of cachexia. Participants' physicians independently rated their decision-making capacity.

Results: Terminally ill participants were significantly more impaired than healthy adults on all MacCAT-T subscales. Most terminally ill participants were able to express a treatment choice (85.7%), but impairment was common on the Understanding (44.2%), Appreciation (49.0%), and Reasoning (85.4%) subscales. Agreement between physician-rated capacity and performance on the MacCAT-T subscales was poor.

Conclusions: The use of the MacCAT-T revealed high rates of decisional impairment in terminally ill participants. Participants' physicians infrequently detected impairment identified by the MacCAT-T. The findings from the present study reinforce the need for engagement in advance care planning for patients with advanced cancer.