To make this determination, a hospitalist needs to know how to assess capacity. Although capacity usually is defined by state law and varies by jurisdiction, clinicians generally can assume it includes one or more of the four key components:
- Communication. The patient needs to be able to express a treatment choice, and this decision needs to be stable enough for the treatment to be implemented. Changing one’s decision in itself would not bring a patient’s capacity into question, so long as the patient was able to explain the rationale behind the switch. Frequent changes back and forth in the decision-making, however, could be indicative of an underlying psychiatric disorder or extreme indecision, which could bring capacity into question.
- Understanding. The patient needs to recall conversations about treatment, to make the link between causal relationships, and to process probabilities for outcomes. Problems with memory, attention span, and intelligence can affect one’s understanding.
- Appreciation. The patient should be able to identify the illness, treatment options, and likely outcomes as things that will affect him or her directly. A lack of appreciation usually stems from a denial based on intelligence (lack of a capability to understand) or emotion, or a delusion that the patient is not affected by this situation the same way and will have a different outcome.
- Rationalization or reasoning. The patient needs to be able to weigh the risks and benefits of the treatment options presented to come to a conclusion in keeping with their goals and best interests, as defined by their personal set of values. This often is affected in psychosis, depression, anxiety, phobias, delirium, and dementia.3
Several clinical capacity tools have been developed to assess these components:
The Mini-Mental Status Examination (MMSE) is a bedside test of a patient’s cognitive function, with scores ranging from 0 to 30.4 Although it wasn’t developed for assessing decision-making capacity, it has been compared with expert evaluation for assessment of capacity; the test performs reasonably well, particularly with high and low scores. Specifically, a MMSE >24 has a negative likelihood ratio (LR) of 0.05 for lack of capacity, while a MMSE <16 has a positive LR of 15.5 Scores from 17 to 23 do not correlate well with capacity, and further testing would be necessary. It is easy to administer, requires no formal training, and is familiar to most hospitalists. However, it does not address any specific aspects of informed consent, such as understanding or choice, and has not been validated in patients with mental illness.
The MacArthur Competence Assessment Tools for Treatment (MacCAT-T) is regarded as the gold standard for capacity assessment aids. It utilizes hospital chart review followed by a semi-structured interview to address clinical issues relevant to the patient being assessed; it takes 15 to 20 minutes to complete.6 The test provides scores in each of the four domains (choice, understanding, appreciation, and reasoning) of capacity. It has been validated in patients with dementia, schizophrenia, and depression. Limiting its clinical applicability is the fact that the MacCAT-T requires training to administer and interpret the results, though this is a relatively brief process.
The Capacity to Consent to Treatment Instrument (CCTI) uses hypothetical clinical vignettes in a structured interview to assess capacity across all four domains. The tool was developed and validated in patients with dementia and Parkinson’s disease, and takes 20 to 25 minutes to complete.7 A potential limitation is the CCTI’s use of vignettes as opposed to a patient-specific discussion, which could lead to different patient answers and a false assessment of the patient’s capacity.
The Hopemont Capacity Assessment Interview (HCAI) utilizes hypothetical vignettes in a semi-structured interview format to assess understanding, appreciation, choice, and likely reasoning.8,9 Similar to CCTI, HCAI is not modified for individual patients. Rather, it uses clinical vignettes to gauge a patient’s ability to make decisions. The test takes 30 to 60 minutes to administer and performs less well in assessing appreciation and reasoning than the MacCAT-T and CCTI.10