Capacity versus competence

Although competency and decision-making capacity are closely related, a meaningful distinction between them exists. Decision-making capacity describes a person’s decisional abilities. Decision-making capacity should not be thought of as an “all or nothing” trait. Instead, persons possess a degree of decision-making capacity, and this capacity can change over time.

In contrast, competency describes whether a person has adequate decision-making capacity to make a particular decision. Thus, a patient may be competent to select a treatment but not competent to decide whether to enroll in a research protocol. Deciding whether a patient is competent also requires considering the particular context and consequences of the decision. For instance, a patient taking medication to treat hypercholesterolemia might believe it works by “purging the liver.” This incorrect belief suggests impairment in the patient’s decision-making capacity (since the patient lacks true understanding of the treatment’s mechanism of action). However, this misunderstanding presents minimal potential negative consequences for the patient. If the patient understood the purpose, risks, and benefits of the medicine to their health, it would be reasonable for clinicians to conclude that this patient is competent to make this decision.

TIPS AND TRICKS

Evaluating decision-making capacity versus competence

Decision-making capacity describes a patient’s decisional abilities. In contrast, competency describes whether a patient has adequate decision-making capacity to make a particular decision.

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Assessing decision-making capacity

There are four widely accepted abilities that constitute decision-making capacity: expressing a choice, understanding, appreciation, and reasoning (Box 10.1). The first ability is the simplest; patients must be able to clearly communicate a choice (e.g. “I do not want a feeding tube”). This choice should be relatively stable over time and not impulsive; thus, when patients express widely fluctuating choices physicians should consider if anxiety is playing a large role.

The second ability – understanding – means patients should be able to grasp significant relevant information which has been presented to them. Practically, this can be assessed by asking patients to paraphrase important information. For instance, the clinician can ask the patient, “Tell me in your own words what I told you about the steps we take to insert a feeding tube.” The goal is to verify that important facts have been successfully communicated.

Deciding what level of understanding is acceptable requires clinicians to exercise judgment. For instance, a patient’s inability to recall whether a tube might be placed in the duodenum versus the jejunum is unlikely to be problematic. In contrast, a patient who is unable to understand that feeding tube placement involves a surgical procedure raises significant concerns about their understanding of a significant fact. Because memory and language are critical for understanding, patients for whom these domains are impaired, such as Alzheimer’s patients, can have significant difficulty meeting this standard.

Source: Appelbaum PS. Clinical practice. Assessment of patients’ competence to consent to treatment. N Engl J Med 2007; 357(18): 1834–40.

While assessing a patient’s understanding is primarily concerned with the successful communication of facts, the third ability – the ability to appreciate – requires patients to demonstrate an awareness of how these facts are personally meaningful. In other words, the patient must not only grasp the facts (e.g. “feeding tubes are for people who cannot get enough food by mouth”), but recognize how these facts relate to their individual situation (e.g. “I cannot swallow and that is why my doctor has talked to me about having a feeding tube”).

Finally, the fourth ability, reasoning, requires a patient to analyze information they have received. Patients ought to display some ability to work through possible consequences of various alternatives and to compare options. The goal of this standard is not to pass judgment on which choice the patient makes, but rather to evaluate the process by which a patient arrives at that decision. Thus, to assess consequential reasoning, one might ask, “How would having a feeding tube affect your daily life?” Similarly, one might assess comparative reasoning by asking, “Why do you prefer not to have a feeding tube placed instead of having this procedure done?” Because the ability to weigh various risks and rewards relies heavily on executive function, patients with significant impairment in executive function such as frontotemperal dementia can find it particularly difficult to reason.

Standardized tools for assessing capacity exist, such as the MacArthur network instruments to assess research or treatment consent capacity. These instruments allow a clinician to thoroughly assess all the relevant abilities for a given decision and then exercise clinical judgment as to whether the patient lacks capacity, a judgment that involves deciding how much impairment in which abilities will describe a patient who lacks capacity.

Important considerations when clinicians suspect that patients lack capacity

Clinicians should not assume that cognitive impairment is the only cause of impaired decision-making capacity. Many processes other than dementia can also impair capacity, including major depression, anxiety, and delirium arising from a variety of medical illnesses. These conditions can be quite prevalent in older patients, particularly those with dementia. In fact, distinguishing whether symptoms stem from dementia or depression can be a challenging task, sometimes requiring dedicated neuropsychological testing. The prevalence of depression, a potentially treatable condition, in Alzheimer’s patients has been estimated to be as high as 30%. Therefore, when clinicians suspect a loss of decision-making capacity, it is important consider all possible causes, not only dementia, particularly as some causes may be amenable to treatment and some degree of decision-making capacity can be restored.

CAUTION

Depression can mimic cognitive dysfunction resulting from progressive dementia. As the prevalence of depression in Alzheimer’s dementia can be as high as 30%, clinicians should always screen for depression in patients with decreased decision-making capacity.

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Although measures of overall cognition, such as the Mini-Mental Status Examination (MMSE), correlate well with clinical judgments of incapacity and can provide a reasonable first step in gauging competence, cognition cannot substitute for a capacity assessment. While studies differ regarding the precise boundaries, broadly speaking, in patients with a MMSE >24, decision-making capacity is generally preserved. Conversely, patients with a MMSE <18 are likely to have significant impairments in decision-making capacity, especially as scores drop below 10.

Finally, it is important to recognize that even when patients possess full decision-making capacity, they have the right to cede the task of deciding to another, possibly a family member or caregiver, very possibly their physician. Clinicians should recognize a patient’s wish to yield decision making to another as a fully valid expression of individual autonomy.

Surrogate decision making: substituted judgment or best interests

As decision-making capacity decreases, caregivers take on the additional role of surrogate decision maker. Two standards drawn from the law may offer guidance for caregivers in how to approach decisions: substituted judgment and best interests. Each reflects a distinct philosophy about how a surrogate decision maker should decide on behalf of a patient who cannot decide for themselves.

A substituted judgment standard argues that the decision maker should reconstruct what decision the patient would have made, if she found herself in that particular situation. Drawing on knowledge of the patient’s beliefs, values and priorities, the surrogate should choose as the patient would have chosen. In contrast, the best interests standard suggests the surrogate decision maker should decide what is best for the patient, not attempt to surmise what she would theoretically have chosen.

One way to distinguish these contrasting views is to describe the substituted judgment approach as primarily concerned with preserving patient autonomy (i.e. trying to decide what the patient would have decided) while the best interests approach prioritizes beneficence (choosing what the surrogate considers best for the patient, regardless of what she would have wanted).

Dementia’s typically gradual course of decline means that patients have the opportunity to consider and express their future wishes with loved ones who may eventually serve as surrogate decision makers. Thus, some ethicists have argued that a surrogate ought to begin by first following any explicit wishes the patient may have expressed, followed by a substituted judgment approach when facing decisions where prior knowledge of patient beliefs allows extrapolation. Finally, when challenged with decisions for which they have no knowledge of what the patient might have valued, surrogates ought to adopt a best interests approach, choosing what they think is best for the patient.

While this tiered model provides useful structure, putting it into practice presents practical complexities. First, substituted judgments are often inaccurate. One study of patients and their designated surrogates demonstrated that surrogates using a substituted judgment framework to decide about future medical scenarios such as stroke or Alzheimer’s were inaccurate >30% of the time. Furthermore, when inaccurate, surrogates consistently chose more aggressive care compared to what patients stated they would choose for themselves. Providing surrogates with a copy of an advance directive completed by the patient did not improve the accuracy of surrogate predictions.

These findings are consistent with the observations of many practitioners involved in end-of-life care. Even when patients leave explicit instructions to withdraw care, it is common for family members to intuitively feel guilty about “abandoning” a loved one when making these decisions. These discrepancies raise significant questions about whether a substituted judgment paradigm for surrogate decision making is realistic.

In defense of substituted judgment, one might argue that even if surrogates make inaccurate predictions, retaining patient wishes as the primary driving factor represents the best hope for decisions to approach what the patient would have wanted. However, this approach must balance at least three considerations.

First, surrogates are also often the primary caregiver and subject to stressors which may significantly affect decisions. For instance, depressed caregivers are less likely to choose cardiopulmonary resuscitation (CPR) for their loved ones. Second, while patients may discuss their treatment preferences with surrogates, for most patients, it is difficult to fully anticipate what they might want in a given situation. Thus, a patient might express a strong desire to “do everything.” However, in practice, even this “ultimatum” may present significant ambiguities: should a surrogate enroll this patient in a trial that offers a 50:50 chance of significant improvement versus significant decline? Occasionally, patients with amyotrophic lateral sclerosis, another incurable neurodegenerative disease, will initially find it inconceivable to imagine consenting to a feeding tube, but change their mind when faced with the reality of swallowing dysfunction. The limited ability of patients to foresee and convey preferences for a multitude of potential scenarios, at a minimum severely limits the situations in which substituted judgment is useful. Third, it is not clear that patients themselves always want their wishes to be followed to the letter. In one study of patients receiving dialysis, two-thirds expressed the desire for their surrogates to exercise “leeway” when interpreting their advance directives should they develop Alzheimer’s disease. Thus, even patients themselves express reservation about surrogates strictly adhering to their instructions in light of future uncertainties.

Substituted interests model

To address the challenges of implementing either one of these approaches in isolation, Sulmasy and Snyder have proposed a blended “substituted interests model” as an alternative. This model acknowledges that attempts to preserve patient autonomy by divining what a patient would have decided in a given situation are ultimately futile and highly stressful for surrogates. Instead, surrogates are asked to speak in their capacity as experts regarding the patient’s values and beliefs. A surrogate’s testimony to distinctive values which characterize a patient provides the foundation for a constructive conversation between clinician and surrogate about what the real interests of the patient might be. Drawing on this knowledge, clinicians can offer surrogates information and guidance on ways in which this patient’s unique profile of interests might be honored in the particular clinical context. Together, clinicians and surrogates can then participate in the process of shared decision making, judging what course of medical action most authentically represent the patient’s interests.

The substituted interests model differs from its predecessors in two distinctive ways. First, according to the substituted judgment and best interests standards, decision-making responsibility rests solely on the surrogate’s shoulders. In contrast, the substituted interests model acknowledges that the heavy responsibility of decision making should be shared between clinicians and surrogates (although ultimate decision continues to rest with the surrogate). Second, where uncertainty exists regarding what the patient would have wanted, decisions are driven by knowledge of the patient’s core values and beliefs, instead of attempts to guess the details of what specific decision the patient would have made. For example, a substituted judgment standard asks the surrogate to determine what particular judgment (i.e. decision) the patient would have made (i.e. “I am sure my father would never have chosen a feeding tube”). Instead, the substituted interests model proposes that the surrogate and physician’s task is to determine what decision best represents the patient’s known interests, i.e. “Two things my father deeply valued were spirited conversations with family and living without pain. Alzheimer’s has made such conversations no longer possible and he has developed painful bedsores and trouble swallowing. Although he never specifically discussed feeding tube placement, having a feeding tube placed to keep him alive would not be in keeping with the things he valued – like relating to family and living pain free.”

Importantly, in this model, specific instructions which the patient left should certainly continue to guide decisions. However, this model suggests that patients should be encouraged to discuss not only specific medical decisions but how strictly instructions should be followed. This substituted interests approach preserves the commitment to patient-centeredness which motivates substituted judgment, but acknowledges that particularly where ambiguity exists, surrogates and clinicians can use the patient’s values to infer what decision best reflects the patient’s interests.

Related posts:

Diagnosis and Differential Diagnosis of Dementia An Approach to the Problem of Normal Pressure Hydrocephalus Depression: Cause or Complication of Cognitive Decline? After the Diagnosis: Continuing Neurological Care of the Outpatient with Dementia Using Psychotropic Medications to Manage Problem Behaviors in Dementia Young Onset Dementia: How Much Diagnostic Testing is Enough?

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