Capacity is a “threshold” element in informed consent. Without the ability to make decisions, a person is not autonomous. Capacity is task specific: patients may be fully capable of making medical decisions even if they are unable to care for themselves in other ways. Capacity waxes and wanes depending on many factors such as the patient’s medical condition, psychological state, level of stress, and ability to orient to unfamiliar surroundings. Although any diagnosis of compromised mentation can interfere with competence, no diagnosis in a conscious patient invariably identifies incompetence. The presence of memory impairment, dementia, or mental illness, for example, does not prove a lack of capacity to make medical decisions.

Physician paternalism and bias pervades assessments of patient competence. Patients are often referred for competency evaluations simply because they refuse medical advice, although such refusals are not generally evidence of incapacity.⁴ In one study, noncompliant patients comprised almost two-thirds of referrals for competency evaluations, yet they were only slightly less likely than compliant patients to be judged incompetent by consultants. Patients who discharge themselves against medical advice from hospitals have a somewhat higher prevalence of alcohol abuse than the general population. However, studies have found that such actions are more often related to insurance status and lower income, or factors such as race (which might be associated with mistrust of physicians or

Physicians frequently judge patient competence based on their perception of the quality of a patient’s decision. A recent study of physicians’ attitudes toward patients who refuse cancer therapy found that physicians often regarded such decisions as “irrational,” and therefore reflecting mental aberrations.⁶ Such judgments place the physician’s own values, prejudices, and perceptions about medical treatment and quality of life before those of the patient, and do not reflect appropriate respect for patient autonomy. The same study found that patients refuse medical therapy based on personal values and experience more than on medical facts alone. Most experts believe that quality of life measures are at least equal in relevance to medical outcomes in determining if treatment results meet patient needs.

In general, competence to make medical decisions is adjudged to be present when the patient meets four criteria: they can communicate a choice, understand the relevant information, appreciate the medical consequences of the decision, and reason about treatment decisions (see also Chapter 4). These criteria generally can be assessed in pre-operative conversations with patients, and do not usually require expert consultation. When there is conflicting evidence about patient competence, however, a formal evaluation may be helpful.

The anesthesiologist in our introductory case made a hasty judgment about whether Allen was capable of participating in a complete discussion of options for his anesthesia care. An actual conversation with Allen would have revealed to her that he is employed, and lives independently – although these circumstances do not guarantee he has capacity for medical decision-making. When asked, he says that he needs to have surgery because of his sick intestines, and that he understands that he could get cancer if he does not have the operation. He also hopes that the surgery will reduce his pain and diarrhea. He does not fear anesthesia; he has been through several operations before without problems. Because of his religious beliefs he does not fear death. Allen appears to be an autonomous person with capacity to decide – or at least participate to a great degree – in decisions about his care, and should be given a complete description of his options in language aimed at his level of understanding.

If delaying surgery allows a patient suffering from a temporary incapacity to recover competence in a time frame such that the surgery is still meaningful, the surgery should be postponed. If an emergency surgery cannot be delayed for a patient with temporary incapacity, then the physician may need to locate a surrogate decision-maker, or proceed without consent in the best medical interests of the patient.