What is the difference between capacity and competence in a patient's ability to make informed medical decisions?

Capacity versus Competence in Medical Decision-Making

Capacity refers to a clinical assessment of a patient's ability to make specific medical decisions at a particular time, while competence is a legal determination made by courts about a person's overall ability to manage their affairs. 1

Key Differences Between Capacity and Competence

Capacity

• Clinical determination: Assessed by healthcare providers in clinical settings 1, 2
• Decision-specific: Relates to a particular medical decision at a specific time 1
• Fluctuating: Can vary over time and with different decisions 1
• Assessed using four key abilities:
  1. Understanding: Ability to comprehend relevant medical information
  2. Appreciation: Acknowledgment of one's condition and treatment consequences
  3. Reasoning: Ability to weigh risks and benefits
  4. Choice: Ability to express a decision 1

Competence

• Legal determination: Formal judgment typically made by courts or judges 1
• Global assessment: Traditionally a broader determination about managing one's affairs 1
• More permanent: Generally a more enduring determination 1
• Legal consequences: Affects rights beyond healthcare decisions 1

Evolution of Concepts

Historically, competence was viewed as an all-or-none determination, with courts making sweeping judgments about a person's ability to manage their affairs. Modern practice has shifted toward recognizing that decision-making ability exists on a spectrum, with capacity assessments being decision-specific 1.

This shift acknowledges that:

• Cognitive impairment exists on a spectrum
• A person may have capacity for simpler decisions but not complex ones
• Capacity for one decision doesn't necessarily imply capacity for all decisions 1

Clinical Capacity Assessment in Practice

When assessing capacity, clinicians should:

1. Presume capacity: Adults are presumed to have capacity unless proven otherwise 1
2. Avoid assumptions: Do not make assumptions based on age, appearance, or behavior 1
3. Provide support: Give all practicable help to enable decision-making before determining lack of capacity 1
4. Respect autonomy: Recognize that unwise decisions alone do not indicate lack of capacity 1

The four-part assessment evaluates whether a patient can:

• Understand relevant information about their condition and treatment
• Appreciate the implications of that information for their situation
• Reason about treatment options using the information
• Communicate a choice 1, 2

Common Pitfalls in Capacity Assessment

• Under-recognition: Clinicians detect less than half of cases where patients lack capacity 3
• Confusing disagreement with incapacity: Patients who refuse recommended treatment are not automatically lacking capacity 1, 2
• Failing to adjust assessment to decision complexity: More complex decisions require higher levels of capacity 3
• Not recognizing fluctuating capacity: Timing assessments during periods of better cognitive function 1
• Making global judgments: Incorrectly assuming that lack of capacity for one decision means lack of capacity for all decisions 1

When Capacity is Lacking

If a patient lacks capacity:

• Identify a surrogate decision-maker according to state law hierarchy (typically spouse, adult child, parent, sibling, friend) 1
• Follow previously expressed wishes when available 1
• Make decisions based on the patient's best interests when prior wishes are unknown 1
• Consider emergency treatment without formal consent only when delay would increase risk of death or serious harm 2

Improving Decision-Making Capacity

When possible, enhance a patient's ability to participate in decisions by:

• Timing discussions for when cognition is better ("good days") 1
• Using plain language and multimodal presentation of information 1
• Providing corrective feedback and information summaries 1
• Adjusting the complexity of information to match the patient's abilities 3

Understanding the distinction between capacity and competence is essential for respecting patient autonomy while ensuring appropriate protection for those who cannot make informed decisions about their medical care.