SUMMARY: Outside the surgical specialties, faulty diagnosis is the commonest type of medical error. Though even the most conscientious physicians sometimes misdiagnose, diagnostic error is more commonly found to have arisen from negligence than are other types of medical mishap. Most misdiagnoses occur because of faulty reasoning. Systemic factors usually contribute.
Caregiver mistakes may arise from cognitive error, lack of skills and failure to complete tasks. Personal causal factors are varied and common.
The process of medical diagnosis is generally viewed as combining hypothetico-deductive reasoning and pattern-matching (heuristics). 1
As soon as a consultation begins, the physician starts generating hypotheses, based on a combination of knowledge and experience.
Selecting among the 2-6 most likely diagnoses is determined by probability, seriousness, treatability and how memorable the disease is. The process is very rapid and automatic. Rapid selection of a hypothesis tends, if anything, to result in greater, not lesser, accuracy.
By contrast, the search for evidence to confirm or refute a diagnosis is "controlled, deliberate and frequently time-consuming." 1
Practical PointerThe art of diagnosis requires conscientious scepticism and an understanding of the likely pitfalls in the process. |
Though even the most conscientious physicians sometimes misdiagnose, diagnostic error is more commonly found to have arisen from negligence than are other types of medical mishap.
Faulty diagnosis is the commonest type of error that results in medical malpractice litigation against physicians in the Emergency Department, 2 [Full Text] general medicine, 3 in some medical specialties 4 [Full Text] and in paid malpractice claims. 5
Causes of erroneous diagnosis can usefully be categorised as no-fault, system-related or cognitive.
No-fault errors 3 are attributable to masked or unusual presentation of a disease, and to patient-related factors such as lack of cooperation and deception.
System-related errors include technical failure, equipment problems and organisational flaws.
Practical PointerNot all diagnostic errors are avoidable and, in those that are avoidable, system-related factors are almost as common as cognitive mistakes |
Most misdiagnoses occur because of faulty reasoning.
Cognitive errors have long been sub-classified in the aviation industry as data collection (SO) - interpretation (A) - plan (P). 6 In primary care medical records, these categories correspond with Lawrence Weed's widely adopted SOAP acronym: Subjective/Objective - Assessment - Plan. 7
Diagnostic errors rarely occur because of lack of knowledge, uncommonly as a result of faulty data gathering and most commonly because of faulty synthesis.
Remedies (
Practical PointerCognitive errors have a variety of origins that must be anticipated and actively prevented |
Systemic factors usually contribute.
A viable Cause of medical malpractice Action requires more than a diagnostic error.
Often both system-related and cognitive errors contribute to erroneous diagnosis. 3 In a study of diagnostic errors in Internal Medicine, system-related errors were present in about two-thirds and cognitive errors in about three-quarters of the cases. 3
Counsel should be aware that assessment of misdiagnosis is particularly prone to hindsight bias. Nevertheless, a variety of cognitive errors are commonly present and should be identified and explicitly addressed by directed medical expert opinion.
Practical PointerDiagnostic errors often have contributory systemic causes and negligence is particularly susceptible to hindsight bias |
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