Physician bias has been identified in capacity evaluations. See Box 2.4,10-12
Tools used in capacity evaluations
Most capacity evaluations are conducted by clinical interview (Box 3). The reliability of physicians’ unstructured judgments of capacity has been poor.13 In a study of 5 physicians who made a determination of capacity after watching a videotape of capacity assessments, the rate of agreement among the subjects was no better than that of chance.14
There is no specific, simple, quick test to assess capacity.
Folstein Mini-Mental State Examination. The MMSE has not been found to be predictive of decision-making capacity. It has been found to correlate with clinical judgments of incapacity, and may be used to identify patients at the high and low ends of the range of capacity, especially among older persons who exhibit cognitive impairment.15 Patients who have severe dementia (MMSE score <16) have a high likelihood of being unable to consent to treatment.16
MacArthur Competence Assessment Tool-Treatment. The MacCAT-T is a structured interviewing tool used to evaluate a patient’s decision-making ability. It is the most commonly used screening tool to evaluate decision-making capacity. Advantages of the MacCAT-T include a higher inter-rater agreement and—unlike other assessment instruments—its ability to incorporate information specific to a patient’s decision-making situation.17 The MacCAT-T requires training and experience to administer.
Physicians make decisions about a patient’s decision-making capacity. Courts determine competence by a formal judicial proceeding. The psychiatric consultant’s role in capacity evaluations is to determine if the patient 1) possesses the requisite knowledge about the specific referral issue and 2) demonstrates a voluntary and reliable decision.