Physicians are not very good at determining medical decision-making capacity, even though incapacity is common. Eighteen to thirty-five percent of medicine inpatients lack capacity. On average, 44% of nursing home bound, 54% of Alzheimer’s, and 68% of learning disabled patients lack capacity. Physicians often receive no formal training in capacity determination and routinely miss incapacity.

Assessments of patient capacity aim to balance the ethical norms of autonomy (self-determination) and beneficence (protection). The finding of incapacity may result in the removal of a patient’s rights.

Informed consent for treatment requires that a patient has decision-making capacity, has been provided all relevant information about the treatment, risks, benefits, and alternatives (unless the patient specifically requests not to be told), and has voluntarily agreed to the treatment. The information should meet either the “community standard” (what would a prudent physician in the same community, with the same background and experience, have disclosed to a patient in a similar situation?), or the “materiality standard” (what would a reasonable patient want to know in a similar situation to make an appropriate decision?).

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Consent is legally presumed in an emergency.

Physicians should recognize potential incapacity, formally evaluate capacity, clearly document evaluation and decision, and follow specific steps if patients lack capacity.


  • Recognize potential incapacity: Physicians typically suspect incapacity when patients disagree with their recommendations. However, physicians should also suspect incapacity when patients agree too quickly to major recommendations, are delirious, or have underlying risk factors like neurological or severe psychiatric illness, low education, language barrier, or age less than 18 or greater than 85 years.

  • Recognize four “core abilities” that constitute capacity, derived from US case law:

    Understanding: comprehension of medical information.

    Appreciation: personalization of information through integration with one’s beliefs and expectations.

    Reasoning: evaluation of alternatives in light of potential consequences.

    Expression of choice: communication of a treatment decision.

  • Avoid relying on general impression of capacity, which has been shown to be unreliable and easily biased.

  • Evaluate capacity using one of the following techniques.

    Detailed discussion incorporating at least the following elements.

    Patient has knowledge of their specific medical situation (“Why are you in the hospital?”).

    Patient is aware of the risk/benefits/alternatives to the decision (“What could happen if you took this treatment? What could happen if you refused this treatment? What can be done to help you besides this treatment?”).

    Patient can incorporate individual personal beliefs and values in decision-making (“I am a Jehovah’s witness and cannot accept blood transfusions.”).

    Patient can communicate the above to the physician.

    Formal determination using validated instruments. At least 19 instruments are available, but no standardized guidelines exist. The Aid to Capacity Evaluation (ACE) has been validated in medical inpatients, is based on the actual decision the patient is making, takes 10-20 minutes to complete, and is available free online for non commercial use (http://www.jcb.utoronto.ca/tools/documents/ace.pdf).

  • Document: the discussion, specific questions and responses, cognitive testing (if done), persons present, and conclusion.

  • What to do if:

    The patient has capacity (autonomy).

    Follow the patient’s decision. In cases of refusal of physician recommendations by competent, informed patients/surrogates, recognize that:

    Patients have the right to make what others may consider unwise choices if the decision-making process is adequate.

    Prognoses are often inaccurate and medical knowledge is finite.

    The provider is unsure if the patient has capacity or is uncomfortable with the patient/surrogate’s decision (for example, the patient/surrogate insists on life-sustaining interventions in the face of medical futility): consider a second opinion (e.g. experienced psychiatrist), ethics consultation, legal counsel, or risk management counsel. Often, there is no “right” answer, but careful and well-documented discussions will help in protecting both patient and providers.

    The patient lacks capacity (beneficence).

    If this is temporary and the decision can be deferred, correct reversible factors and reassess.

    If this is permanent or the decision cannot be deferred, follow an advance directive (AD) completed by the patient when he or she possessed capacity, if the AD specifies the patient’s wishes.

    If the AD does not provide definitive guidance or no such document exists, consult the appropriate surrogate decision-maker. If the patient has a Durable Power of Attorney for Health Care (DPAHC) specifying a surrogate, the physician should consult that person only. If a surrogate is not formally identified, many states have laws that recognize a hierarchy of appropriate decision-making authority, such as: spouse (not divorced or legally separated), legal partner, a majority of adult children who can be reasonably contacted, parents, domestic partner, siblings, nearest living relative, close friend, and attending physician in consultation with an ethics committee. Most patients (87%) believe their surrogates will make the right decision. Of note, however, surrogate accuracy in stating the patient’s preferences is in fact limited (approximately 50-65% in some studies).

    If neither an AD nor a surrogate is available, in the short term consider ethics counsel, legal counsel or risk management counsel PRIOR to providing care that most patients would likely want in non-emergent situations. In the long term, pursue a legal declaration of incompetency and legal guardianship.


In clinical emergencies and in the absence of advance directives or a surrogate decision-maker, providers may deliver standard medical interventions that would be acceptable to most patients without evaluating capacity.

Capacity decisions are task specific. Patients may have capacity to make simple decisions (antibiotics for infection) even if they have risk factors for incapacity, but they may lack capacity for more complex decision-making (renal transplant). However, although the impairment of capacity is a spectrum, the physician’s judgment about capacity is binary: either the patient does or does not possess it at this time for this clinical decision.

Capacity decisions are temporal. Incapacity to make medical decisions may be temporary and reversible (encephalitis) or permanent (Alzheimer’s). Capacity is open to change and influence and must therefore be assessed continuously.

“Pseudo” incapacity occurs when the clinician presents information in a manner inappropriate to a patient’s level of health literacy (use of jargon, not in their primary language, not at their education level, etc.). Capacity assessments are only as good as the physician’s disclosure.

Any licensed physician can determine capacity. Ideally it is done by the physician who will provide the specific medical decision under discussion (e.g. orthopedic surgeon for hip replacement) or a provider who is fully knowledgeable about the specific decision and knows the patient well over time (primary care physician).

A psychiatry evaluation is not routinely required for patients with mental illness unless it is severe or felt to be impairing decision-making.

Tests of cognition like mini-mental state examination (MMSE) are not tests of capacity. However, a MMSE less than or equal to 19 significantly increases the likelihood of incapacity (LR=6.3) and a MMSE score greater than or equal to 25 significantly decreases the likelihood of incapacity (LR = 0.14).

In general children below the age of majority (or unemancipated) are presumed to lack decision-making capacity.

“Competency” is a legal term and refers to an individual’s ability to function in society. It is determined by a court of law, not by physicians.


Any licensed physician can determine capacity. A “gold standard” might be a determination by a practitioner who has formally trained to do the examination and has performed an extensive number of examinations, or the decision of a court of law. However, no national standards or benchmarks have yet been established.

Appelbaum, PS. “Assessment of Patients' Competence to Consent to Treatment”. N Engl J Med. vol. 357. 2007. pp. 1824-40.

Etchells, E, Darzins, P, Silberfeld, M. “Assessment of patient capacity to consent to treatment”. Journal of General Internal Medicine. vol. 14. 1999. pp. 27-34. (This article describes and validates the Aid to Capacity Evaluation.)

Grisso, T, Appelbaum, PS.. Assessing Competence to Consent to Treatment: A Guide for Physicians and Other Health Professionals. 1998. (This book remains the seminal text in this field.)

Howe, E. “Ethical Aspects of Evaluating A Patient's Mental Capacity”. Psychiatry. vol. 6. 2009. pp. 15-23.

Lamont, S, Jeon, Y, Chiarella, M.. “Assessing patient capacity to consent to treatment: an integrative review of instruments and tools”. Journal of Clinical Nursing. vol. 22. 2013. pp. 2387-2403. (This article is a comprehensive review of capacity determination and available instruments.)

Schneider, PL, Bramstedt, KA.. “When psychiatry and bioethics disagree about patient decision making capacity (DMC)”. Journal of Medical Ethics. vol. 32. 2006. pp. 90-93. (This article explains how ethics consultants and psychiatrists may assist in determinations of capacity.)

Sessums, LL, Zembrzuska, H, Jackson, JL. “Does This Patient Have Medical Decision-Making Capacity?”. JAMA. vol. 306. 2011. pp. 420-427.