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Geriatric Anesthesia

Informed Consent and Cognitive Dysfunction After Noncardiac Surgery in the Elderly

Hogan, Kirk J. MD, JD*; Bratzke, Lisa C. RN, PhD; Hogan, Kendra L. JD, MPH

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doi: 10.1213/ANE.0000000000002689
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In one respect at least the Martians are a happy people; they have no lawyers.

—Edgar Rice Burroughs1

If you go to law school to palliate a midcareer crisis in anesthesiology, you may be amused to discover that the first class of the first semester is Torts, the first tort is battery, the first battery is unconsented touching, and the first court cases of unconsented touching arose during surgery under general anesthesia.2 Accordingly, the doctrine of informed consent is the Magna Carta of perioperative medicine. Since resolution of early battery lawsuits at the turn of the last century, judicial analysis of informed consent before surgery has shifted from the tort of battery to the tort of negligence, ie, a legal wrong at the hands of another who has failed to take due care to avoid what a reasonable person would regard as a foreseeable risk. Under the theory of negligence, caregivers owe a duty to fully inform their patients of the benefits and risks of a procedure. Failure to do so is a breach of this duty.3 At issue is the content of the informed consent disclosure in view of the identity of the reasonable person, and the foreseeability of the risk. In the United States, 24 states apply a “physician-based standard” that obliges a caregiver to disclose risks that a reasonable medical practitioner would make under the same circumstances.4 Twenty-three states adjudicate a “patient-based standard” in which a jury decides if an undisclosed risk would have been relevant or “material” to a reasonable patient in a similar situation. New Mexico and Minnesota require a blended standard. Caregivers in North Carolina must satisfy both standards. All courts agree that informed consent before a procedure must be voluntary, competent, and documented. No state court, legislature, federal agency, professional school, training program, medical licensing board, accreditation council, specialty association, or risk management office provides formal guidelines for amending the content of informed consent before surgery in view of new scientific information.5

Since the introduction of general anesthesia in the 1840s, our central dogma has been that loss of awareness and cognition during surgery and anesthesia is reversible in full. We now know that 12% of patients over the age of 60 years with normal cognition on neuropsychological testing before noncardiac surgery do not return to baseline performance by 3 months after surgery, with deficits observed in tasks of memory, processing speed, attention, language, and problem solving.6 Twenty years after the first report of “postoperative cognitive dysfunction (POCD)” there is no evidence to the contrary.7,8 What happens in patients who are cognitively symptomatic before surgery appears to be worse, although the percentage of seniors with cognitive impairment before elective surgery is high.9,10 What happens 12 months after surgery and thereafter (ie, “persistent POCD”) is unknown; prospective studies beyond 12 months are lacking. The incidence of POCD after regional anesthesia is no different than the incidence after general anesthesia.11 There are no peer-reviewed case reports of POCD. The incidence of POCD in twins, families, or other cohorts related by descent or by shared environmental exposures has not been reported. Because patients do not routinely undergo neuropsychological testing before surgery, POCD has only been diagnosed in the research setting. Even in the research setting, neurologists have not participated in POCD investigations to rule out other causes of cognitive decline after surgery. Moreover, an indeterminate proportion of elderly patients may experience “postoperative cognitive improvement” as a consequence of a favorable surgical outcome.12

Differences between published POCD investigations in experimental design, nomenclature, components of psychometric test batteries, thresholds for categorizing abnormal results, diverse control populations, variable test intervals after surgery, heterogeneous statistical methods, and lack of consensual research and publication best practices hamper further resolution of POCD risk estimates after noncardiac surgery. The effect of surgery on the tempo of normal cognitive aging is not known. The relationships among postoperative delirium, POCD, and postoperative dementia are uncertain. Investigations in animals and in administrative human data sets collected for other purposes are useful to generate testable hypotheses, but are not substitutes for prospective trials with human cognitive traits as experimental end points. In contemporary clinical care, it is not possible to communicate the cause of POCD, to predict POCD, to diagnose POCD, to treat POCD, to assign a prognosis to POCD, or to prevent POCD other than to forego a surgical procedure. Taken together, these facts in view of the law of informed consent suggest that it is timely to consider whether or not the risk of POCD should be disclosed to patients over 60 years who are contemplating elective, noncardiac surgery.

Should patients be informed of a clinical risk that is a “research construct”?13 We contend that patients over 60 years who are weighing surgery that requires general anesthesia, or that requires regional anesthesia comprising spinal, epidural or major nerve blockade, should be informed of the risk of POCD. Patients having surgery with light sedation may also be susceptible although these data await confirmation.14 Knowledge of POCD satisfies conventional thresholds of foreseeability, with an incidence far greater than other complications that are presently imparted to patients before surgery including drug allergy, transfusion reaction, myocardial infarction, stroke, awareness, and heritable disorders (eg, malignant hyperthermia). A 3- to 4-fold increase in the odds for new onset memory and problem solving deficits after surgery is clearly material under both a physician- and a patient-based standard. A large majority of patients prefer that complications with a high likelihood but low degree of severity be discussed together with those with a low likelihood but high degree of severity.15 POCD is both common and severe, with profound implications for a patient’s return to work and critical activities of daily living, and a 5-fold increase in the likelihood of death in the first year after surgery.16 Beyond question, patients should be informed that the “safety step” of not undergoing surgery is theirs to choose. Each patient must determine if the proposed benefits of a procedure outweigh the foreseeable and material risks of cognitive decline after surgery, in keeping with our profession’s core values of autonomy and beneficence.17

Who should tell a patient about the risk of POCD? The duty to disclose the risk of POCD falls to the party in charge of the safety step. The duty to disclose is not bound by an assumed etiology of the syndrome, or by the professional specialty of those who discovered the syndrome. We propose that the surgeon and caregivers, under the surgeon’s supervision including advanced practice nurses and physician assistants, are responsible for ensuring that a patient is properly informed of the risk of POCD, in addition to the risks of foregoing a procedure. Only the surgery team is positioned to discuss alternative treatment options. For the present, anesthesia care offers no validated POCD safety step. If such a safety step becomes available to anesthesiologists comprising alternative drugs and techniques, then anesthesiologists and caregivers under the anesthesiologists’ supervision must also participate in the informed consent disclosure, but not to the exclusion of the surgeon’s leading role. Anesthesiologists are not trained in ascertaining the legal competence of a patient with signs and symptoms of cognitive decline to provide consent, or in the interpretation of preoperative neuropsychological testing. Anesthesiologists do not evaluate patients at 3 months or longer after surgery. Anesthesiologists are not credentialed in the differential diagnosis of cognitive dysfunction caused by a diversity of disorders other than POCD such as stroke, seizure, trauma, intoxication, infection, and neurodegenerative conditions unrelated to surgery.

When should a patient be told about the risk of POCD? For consent that is truly informed, patients must learn about the risks of POCD before a surgical procedure is scheduled. Patients and their families facing elective surgery are entitled sufficient time to have questions answered, reflect on personal priorities and values, and balance acceptable and unacceptable risks. During the transition from no POCD disclosure at present to broadened POCD disclosure in the future, it may be commonplace for a patient to learn about a 1 in 10 or greater risk for cognitive decline 3 months after surgery for the first time in the anesthesia preoperative clinic, or on the gurney in the surgical holding area. What is the proper action for the anesthesia caregiver to take under these circumstances? Providers may wish to have agreed on options expressly laid out in advance.

What should a patient be told about the risk of POCD? We counsel that the content of informed consent for POCD risk be guided by a “physician-as-patient–based standard.” What would you wish to know before your own surgery, or surgery in a family member? A minimum disclosure comprises: a definition of POCD; the incidence of POCD 3 months after noncardiac surgery in cognitively healthy patients aged 60 years or older; that the effects of presurgical cognitive deficits are unknown; reassurance that many if not all patients with POCD may recover 12 months after surgery although the evidence is scant; risk factors for POCD that are not modifiable (eg, age and education); that regional anesthesia and light sedation may not be protective; that the cause of POCD is unknown; that there is no specific treatment for POCD; that the implications of POCD for accelerated cognitive aging are unsettled; that POCD is an active and growing research focus including proposals for introduction of cognitive testing before and after surgery as a routine; and that not having surgery may deprive a patient of postoperative cognitive improvement coincident with removal of pain and inflammation, and resumption of normal nutrition, sleep, and physical activity.

How should a patient be told about the risk of POCD? We recommend that a basic disclosure similar to that proposed above be conducted in person. For patients desiring further information, verbal and nonverbal cues in addition to specific prompts may suffice to direct a patient to digital multimedia configured to be interactive and personalized at a patient’s preferred rate and level of detail (eg, “Would you like to learn more?”), that accommodates different degrees of literacy and language proficiency, and that provides and documents a standardized scope of disclosure and shared decision making.18 Technical innovations such as augmented reality and artificial intelligence may 1 day be harnessed so that the content and quality of informed consent before surgery and anesthesia keep pace with scientific discovery.

While informed consent in contemporary practice readily adapts to the introduction of novel drugs, devices, and techniques, it does not readily adapt to the discovery of new risks attendant to everyday drugs, devices, and techniques in decades of widespread use. POCD is a syndrome discovered almost wholly by 1 specialty (ie, anesthesiology) that is almost wholly the clinical burden of other specialties (ie, surgery and nursing).19,20 In addition to anesthesiologists, surgeons, and nurses, we urge that all professionals with a stake in perioperative care including rule and policy makers at multiple levels, payers, patient advocates, plaintiff and defense attorneys, and specialist society members acquire and maintain familiarity with the best evidence of POCD risk, and warrant that consent before surgery is medically and legally informed. Disclosure of other postoperative cognitive syndromes in the elderly including emergence delirium, postoperative delirium, and postoperative dementia as distinct risks is belated.21 Adoption of the Nomenclature Consensus Working Group’s recommendations for the nomenclature of cognitive change associated with anesthesia and surgery will accelerate this transition.22 In turn, routine preoperative cognitive assessment of older surgical patients as endorsed by the American College of Surgeons and the American Geriatrics Society is key for patients, families, and caregivers to improve risk estimates.23 The law of informed consent before surgery has changed little in recent decades, but medical knowledge evolves from month to month. Failing to engage in formal means of ensuring that informed consent policy and practice tracks new scientific data renders patients and their families a disservice.


Name: Kirk J. Hogan, MD, JD.

Contribution: This author helped write the manuscript.

Name: Lisa C. Bratzke, RN, PhD.

Contribution: This author helped write the manuscript.

Name: Kendra L. Hogan, JD, MPH.

Contribution: This author helped write the manuscript.

This manuscript was handled by: Robert Whittington, MD.


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