Medical Capacity

The terms “competence” and “capacity” are often used interchangeably; however:

• Competence refers to the general ability to make independent decisions and is a legal judgment determined in court.

• Capacity refers to the ability to make a specific medical decision and is determined clinically by a physician.

Medical Capacity: Assessment for medical capacity is one of the most common reasons for requesting a psychiatric consult, but any physician can assess decision-making capacity. Issues of medical capacity are common in the inpatient setting and are critical to obtaining informed consent. Hospitalized patients may have acute illnesses that affect their otherwise normal capacity to make decisions. However, impaired decision-making in hospitalized patients is often undetected.

Capacity is goal specific — for example, a patient can have the capacity to accept medication treatment but lack the capacity to refuse surgical interventions. Thus, the primary care team should never ask for a psychiatry consultation to assess a patient’s global capacity. Rather, the specific goal of the consult should be clarified (e.g., capacity to refuse X, capacity to leave against medical advice). Although psychiatrists are often consulted about matters of capacity, all physicians can and should be able to determine capacity (see below). A psychiatric consultation should only be called if the decision-making capacity for a goal in question is thought to be due to a psychiatric disorder (e.g., patient is depressed and thus refusing tube feeds).

Any illness or treatment that affects a patient’s thinking may reduce medical capacity. Efforts should be made to address any reversible medical causes contributing to reduced decision-making capacity (e.g., delirium).

The following disorders are associated with high rates of impaired decision-making:

• delirium

• Alzheimer disease and other dementias (depending on severity)

• stroke (depending on the area affected)

• schizophrenia or other psychotic disorder

• symptomatic bipolar disorder

• severe depression

Assessing decision-making capacity: The following table describes the four clinical criteria for determining decision-making capacity and offers approaches for the assessment of the patient:

(Source: Assessment of Patients’ Competence to Consent to Treatment. N Engl J Med 2007.)

The following links provide tools for assessing medical capacity:

• Areas and Suggested Questions for Specific Capacity Assessments Using the Aid to Capacity Evaluation

• Standardized Mini-Mental State Examination

• Montreal Cognitive Assessment (requires registration) is more sensitive than the mini-mental state exam.

• MacArthur Competence Assessment Tool for Treatment is a more formal assessment that takes about 20 minutes to administer.

Impaired medical decision-making capacity: When a patient is found to have impaired medical decision-making capacity, a substitute decision-maker should be sought:

• In emergencies only, the physician can provide care under the presumption that a reasonable, competent person would have consented to that treatment.

• Patients with advanced directives may have previously indicated their preferred treatment or designated a surrogate decision-maker.

• In the absence of an advance directive or health care proxy, family members can usually make decisions, depending on statutes in each state.

• In the absence of family or health care proxy or in cases of familial dispute, the decision may require resolution by a court (except in emergencies).