Clinicians Often Fail to Recognize Patients Who Lack Decision-Making Capacity
The Aid to Capacity Evaluation is the most clinically valuable instrument for identifying incapacity.
Physicians often ask patients to make complex choices about diagnostic studies or treatments. Medical decision-making capacity includes a patient’s ability to understand relevant information and appreciate the consequences of a decision. Physicians frequently lack formal training in assessing patients’ capacity and regularly fail to identify patients who are incapable of making informed choices.
Researchers reviewed more than 40 high-quality prospective studies of inpatients, outpatients, and healthy controls in which medical decision-making capacity was evaluated with various instruments; patients with severe psychiatric illness were excluded. Incapacity (as judged by a gold standard of forensic or expert psychiatric evaluation) was common in medical inpatients (26%); physicians missed identifying patients with incapacity 58% of the time. Although the Mini-Mental State Examination (MMSE) is not designed to assess decision-making capacity, scores <20 or >24 correlated with lower and higher likelihood of capacity, respectively, whereas scores of 20 to 24 did not correlate with capacity. Of nine instruments that were compared with the gold standard, the Aid to Capacity Evaluation (ACE) performed best. Furthermore, the ACE is free online and evaluates patients’ actual decisions, unlike other instruments, which focus on unrelated clinical vignettes.
Comment: Clinicians often do not assess decision-making capacity adequately, but correct identification of capacity is a necessary prerequisite for valid informed consent. When capacity is evaluated formally, clinicians often rely solely on measures of cognition (e.g., MMSE score) and can miss decision-making incapacity. This study serves as a reminder that lack of decision-making capacity is highly prevalent among inpatients, and the ACE is the best resource to improve identification of such patients.
Aaron J. Calderon, MD, FACP
Published in Journal Watch Hospital Medicine September 12, 2011