Capacity (Competence) Determination and Informed Consent


  • Personal autonomy in decision-making is a fundamental personal freedom.
  • Capacity determination is an inherent element of the informed consent process.
  • It is universally presumed that patients aged ≥18 years (or an emancipated minor under individual state laws) have legal and clinical capacity to give informed consent for health care testing, interventions, and treatment or to refuse same no matter the harm or benefit until proven otherwise.


  • Capacity:
    • Involves a clinical evaluation by a credentialed health care provider
    • Focuses on perceived ability of patient to participate and understand the process of informed consent
  • Competence:
    • A legal determination of abilities, performed by a court judge
    • Involves medical information but does not need to be limited to only medical issues
  • Capacity is the currently preferred term to competence: legal capacity and medical capacity.
  • A capacity determination is needed when arriving at a health care decision for testing, treatment, or an intervention involving risk of harm or no improvement.
    • Any treating health care provider can evaluate capacity, including the provider also obtaining informed consent (although a psychiatrist or neuropsychiatric consultant is often asked to weigh in, other health care providers can determine capacity).
  • Medical capacity is determined by:
    • Clinical observation and response to questions
    • Capacity assessment tool(s)
    • Cognitive assessment tool(s)
    • Interviews with a guardian or designated health care power of attorney (if indicated)
  • The four “C”s of capacity are:
    • Context: comprehension of their health status
    • Choices: able to describe options
    • Consequences: able to explain possible outcomes
    • Consistency: continuity of choice selection
  • Adequate cognition is a fundamental component but not the sole determinant of capacity (1).


Most adults in the United States do not have an advanced directive—population studies show approximately 1/3 have completed an advanced directive (2).

Need for capacity determination has been increased due to:

  • Increasingly older population
  • Prolonged chronic disease states
  • Better patient rehabilitation opportunities
  • Safer anesthetics and advanced postsurgery care

Prevalence varies based on the patient risk factors (pretest probability) and physician experience:

  • ~3% of healthy outpatient seniors lack capacity.
  • Highest rate of incapacity (68%) is in learning disabled patients.

Etiology and Pathophysiology

  • Dementia is the most common reason individuals are found incapable of making health care decisions in the outpatient setting.
  • Capacity is a dynamic state; reassessment is necessary with each significant health care decision and informed consent.

Risk Factors

  • For incapacity:
    • Longevity, multiple comorbidities, hospitalized for medical reasons
    • Never married, never worked outside home
  • Insufficient informed consent:
    • Patient factors:
      • Health illiteracy
      • Excessive information
    • Provider factors:
      • Inexperience with process (house staff for example)
      • Insufficient discussion time

General Prevention

Early assessment and periodic reassessment of capacity in:

  • Dynamic patient conditions, like electrolyte imbalance, closed head injuries, delirium states
  • After procedures with anesthesia or analgesics
  • Enhancement and dissipation of mind-altering substances

Commonly Associated Conditions

  • Dementia/Alzheimer disease, Parkinson disease, and traumatic brain injury
  • Schizophrenia, depression, and substance abuse
  • Acute illness, metabolic derangement

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