Capacity Assessment
Background
Capacity refers to a patient’s ability to understand, appreciate, and make informed decisions about their medical care. It is decision-specific and time-specific, meaning a patient may have capacity for one decision but not another, or may regain capacity later. Unlike competence, which is a legal determination, capacity is a clinical judgment made by healthcare professionals.
Clinical Features
Features indicating possible impaired capacity include:
Confusion, disorientation
Delusions or hallucinations
Expressing choices inconsistent with known values
Inability to explain the nature or consequences of decisions
Fluctuating mental status or consciousness
Differential Diagnosis
Delirium (often reversible and acute)
Dementia (usually progressive and chronic)
Psychiatric illness (e.g., psychosis, depression)
Intellectual disability
Aphasia or language barriers
Influence of medications, intoxication, or metabolic derangements
Evaluation
Workup
Clinical interview focused on the four key elements of capacity:
- Understanding: Can the patient explain the condition and options?
- Appreciation: Does the patient recognize how the information applies to their situation?
- Reasoning: Can the patient compare risks/benefits and explain their choice?
- Communication: Can the patient clearly express a stable choice?
Assess for reversible causes (e.g., hypoxia, infection, intoxication)
Use structured tools if needed: MacCAT-T (MacArthur Competence Assessment Tool for Treatment), Aid to Capacity Evaluation (ACE)
Consult psychiatry if unclear or complex
Diagnosis
Capacity is not all-or-none and should be judged relative to the complexity and risk of the decision. A patient with mild cognitive impairment may still have capacity for low-risk decisions. Document reasoning and patient responses thoroughly.
Management
If the patient lacks capacity:
- Identify appropriate surrogate decision-maker (per legal hierarchy)
- Consider temporary holds or guardianship if no surrogate is available
- Treat reversible impairments and reassess
- Ensure decisions are patient-centered, honoring prior expressed wishes or advance directives
- Involve ethics consultation if disputes arise
Disposition
If capacity is regained, defer major decisions until reassessment
If patient lacks capacity and is at risk, consider admission or legal measures for protection
Ensure continuity of care planning with healthcare proxy or legal guardian
See Also
External Links
Aid to Capacity Evaluation (ACE)
American Bar Association: Capacity Assessment Guidelines