Diagnostic Error

A diagnostic error is a failure to establish an accurate and timely explanation of a patient's health problem, or a failure to communicate that explanation to the patient. It includes diagnoses that are missed, wrong, or delayed, whether or not the patient is ultimately harmed. Diagnostic error has been described as a large and under-recognized component of patient harm, because it is hard to detect, often becomes apparent only in retrospect, and arises from both clinician reasoning and the systems that support diagnosis.

Definition

Diagnostic error is the failure to establish an accurate and timely explanation of a patient's health problem, or the failure to communicate that explanation, encompassing missed, wrong, and delayed diagnoses.

Scope

This topic covers how diagnostic error is defined and classified, its principal cognitive and system-related causes, the challenges of measuring it, and why it has historically received less attention than other safety problems. It treats diagnostic error as a reference and educational subject within patient safety; it is not a guide to diagnosing or managing any specific condition.

Core questions

• How is diagnostic error defined, and how does it differ from an adverse outcome that follows correct diagnosis?
• What are the relative contributions of cognitive factors and system factors to diagnostic error?
• Why is diagnostic error particularly difficult to measure?

Key concepts

• Missed, wrong, and delayed diagnosis
• Cognitive (no-fault, faulty knowledge, faulty processing) errors
• System-related contributing factors
• Cognitive bias and heuristics
• Anchoring and premature closure
• Diagnostic timeliness and communication

Key theories

Dual-process model of clinical reasoning

This account distinguishes fast, intuitive pattern recognition (System 1) from slow, analytical reasoning (System 2) and attributes many cognitive diagnostic errors to faulty heuristics and biases that arise when intuitive reasoning goes unchecked; it is widely used to explain the cognitive component of diagnostic error.

Mechanisms

Analyses of diagnostic error commonly separate no-fault errors (where the disease is silent or atypical), system-related errors (such as failures in test reporting, handoffs, or access), and cognitive errors (such as faulty information gathering, flawed knowledge, or biased reasoning). Many cases involve a combination of cognitive and system factors. Within the cognitive domain, biases such as premature closure, in which a diagnosis is accepted before it is fully verified, and anchoring, in which initial impressions are not revised, are recurrent contributors.

Clinical relevance

Diagnostic error is a major source of preventable harm and is central to understanding how diagnosis can fail at both individual and system levels. This topic describes the nature and causes of diagnostic error for educational purposes; it does not provide diagnostic criteria or treatment advice for individual patients.

Epidemiology

Diagnostic error is difficult to quantify because it is often identified only in retrospect, but autopsy, record-review, and other studies suggest it is common and contributes substantially to harm. Reviews have summarized estimates indicating that a meaningful proportion of patients experience diagnostic error over their lifetime, while emphasizing that the figures vary with method and setting and are subject to considerable uncertainty.

History

Diagnostic error received less early attention than medication and procedural errors, in part because it is harder to detect. Graber and colleagues' classification of diagnostic error into no-fault, system, and cognitive categories helped structure the field, and the 2015 National Academies report Improving Diagnosis in Health Care reframed diagnostic error as a definable, measurable, and improvable patient safety problem.

Debates

Are diagnostic errors mainly cognitive or mainly systemic?

Some accounts emphasize clinician reasoning and cognitive bias, while others stress system failures in test follow-up, communication, and access; most evidence suggests the two interact, and the balance shapes whether interventions target individual reasoning or system redesign.

Key figures

• Mark Graber
• Pat Croskerry
• Hardeep Singh

Seminal works

• graber-2005
• graber-2013
• nasem-2015

Frequently asked questions

Does every diagnostic error harm the patient?

No. A diagnosis can be missed, wrong, or delayed without the patient suffering harm; diagnostic error refers to the failure of the diagnostic process itself, which may or may not lead to an adverse outcome.

Why is diagnostic error hard to measure?

Diagnostic accuracy often becomes clear only as a disease evolves or at autopsy, so errors are frequently recognized only in retrospect, and there is no single reliable detection method, which makes incidence estimates uncertain.