Table 1.

Selected cognitive biases associated with antibiotic use

Bias	Definition	Example	Managing the bias
Anchoring	Fixating on certain diagnostic features early in the process. Initial impression can be powerful and a challenge to deviate from, even once new information becomes available. Anchoring can lead to ‘premature diagnostic closure’ where other diagnoses may not be considered.	Altered mental status in an elderly nursing home resident may often be considered to be caused by UTI before other causes are ruled out. Antibiotics are often initiated in these patients even though antibiotics do not confer any survival benefit.43	Decision support and algorithms to trigger assessment of other causes for non-specific symptoms (e.g., dehydration in the older patient with altered mental status).   Re-evaluation of antibiotic therapy once further information is available (e.g., antibiotic time-out).
Availability bias	Overestimating the likelihood of events that are more memorable. See Negativity effect.	There may be a tendency to select an antibiotic that has had recent perceived success and avoid antibiotics with recent perceived failure.33 Physicians who recalled that they had frequently cared for bacteraemic patients were more likely to over-estimate bacteraemia in a current patient.44	Estimate and re-evaluate confidence in predictions. Provide and reflect upon statistical data showing the risks and benefits of each option and its alternatives.
Commission bias	Tendency towards action over inaction. This may be influenced by the perception that doing something is better than nothing; the regret associated with an omission error outweighs that of a commission error, and may be augmented by patient and family demand.	Antimicrobial stewardship recommendations are more likely to be accepted if they expand antibiotic spectrum compared with reducing spectrum,45 and are more likely to be accepted if they increase antibiotic exposure rather than decrease exposure.46 Concerns about missing an infection outweigh concerns about serious antibiotic harms such as Clostridioides difficile infection.47	Sharing narratives and stories of harm associated with antibiotic commission or overuse (e.g., C. difficile infection or antibiotic-resistant infections).48 Thorough evaluation of risks and benefits of antibiotic therapy and withholding antibiotic therapy, ideally at the point of care.
Confirmation bias	The tendency to seek out evidence that confirms an initial hypothesis and reject information that refutes it. This is an especially powerful bias as it helps to reduce cognitive overload associated with evaluating other alternative hypotheses.	An initial suspicion of UTI in a patient with non-specific symptoms is often ‘confirmed’ by a positive urine culture or dipstick result, leading to unnecessary antibiotic treatment.49 Clinicians and patients may justify antibiotics retrospectively based on symptom resolution, for example, for upper respiratory tract infection, where the natural course of illness is self-resolution with or without antibiotics.	Seek out disconfirming evidence, e.g. use of mnemonics to remind clinicians of alternative diagnoses.4 Provide statistical data on the likelihood of infection (and spontaneous resolution), colonization, and contamination in specific patient populations.
Diagnostic momentum	An initial suspicion can gather momentum and quickly become solidified as a diagnosis as it passes from the patient to health care provider and then across disciplines during the course of illness.	Antibiotics initiated unnecessarily in the ED for suspected UTI are often continued once the patient is hospitalized.50 Although β-lactam allergy labels are common, <10% represent true IgE-mediated hypersensitivity. Penicillin allergy labels reported by the patient and accepted at face value can lead to selection of suboptimal therapy.51 Once reported, a penicillin allergy is often difficult to remove.	Re-evaluation of antibiotic therapy upon healthcare transitions (e.g., ED to ward, upon discharge). Structured communication tools to assist nurses in transferring adequate information regarding long-term care residents with suspected infection to prescribers.52 Use of checklists and frameworks to re-evaluate β-lactam allergies.53
IKEA effect	The tendency of a person to place higher value on, and satisfaction with, a product if they made it themselves.	At the individual-patient level, physicians may be more likely to support a given antibiotic regimen if they were the initial prescriber. At the programmatic level, clinician involvement in antibiotic stewardship strategy selection is associated with increased appropriateness of antibiotic use.54	Engage end users and prescribers early in process of antibiotic stewardship strategy and guideline development.
Negativity effect	Experienced negative outcomes make a greater impression than equally positive outcomes and as a result may be deemed to be more frequent than their actual occurrence.55	Adverse outcomes (side effects, relapse) may be more easily recalled and alter decision making to less judicious therapy (e.g., broader spectrum agents, longer duration).	Reassurance through face-to-face discussion. Provide and reflect upon statistical data showing the risks and benefits of each option and its alternatives.
Optimism or Impact bias	Clinicians and patients have a tendency to overestimate benefits and/or underestimate risks of a specific test or treatment.6,56	Parents of patients vastly underestimate the benefits of antibiotic therapy on symptom duration for upper respiratory tract infections.57 Physicians tend to perceive antibiotic resistance as a problem, but that it tends to be driven by other prescribers in different practice settings.28	Participating in shared decision making with patients, discussing both the benefits and risks of each option can help manage patient expectations and reduce unnecessary antibiotic use.58
Present bias (hyperbolic discounting)	Tendency to favour smaller more immediate benefits over larger benefits in the future.	The immediate benefit of antibiotics that increase patient satisfaction and potentially improve symptoms is weighed more heavily than later outcomes such as antibiotic resistance or C. difficile infection.	Providing cues to prescribers about potential antibiotic risks at the time of prescribing to re-calibrate benefits-versus-risk assessment.