Types of Medical Error

Types of Errors

Diagnostic

• Error or delay in diagnosis
• Failure to employ indicated tests
• Use of outmoded tests or therapy
• Failure to act on results of monitoring or testing

Treatment

• Error in the performance of an operation, procedure, or test
• Error in administering the treatment
• Error in the dose or method of using a drug
• Avoidable delay in treatment or in responding to an abnormal test
• Inappropriate (not indicated) care

Preventive

• Failure to provide prophylactic treatment
• Inadequate monitoring or follow-up of treatment
• Other
  • Failure of communication
  • Equipment failure
  • Other system failure

Source: Leape, Lucian; Lawthers, Ann G.; Brennan, Troyen A., et al. Preventing Medical Injury. Qual Rev Bull. 19(5): 144–149, 1993

Errors can be categorized as slips, lapses, or mistakes.

• Slips can be thought of as actions not carried out as intended or planned, e.g., injecting a medication intravenously when you meant to give it subcutaneously. Slips are observable.
• Lapses are missed actions and omissions (e.g., forgetting to monitor and replace serum potassium in a patient treated with furosemide for acute congestive heart failure). Lapses are generally not observable (i.e., one cannot directly “see” a lapse of memory).

Both slips and lapses are actions that do not “go as intended.”

• Mistakes are a specific type of error brought about by a faulty plan or incorrect intentions; the intended action is wrong (e.g., extubating a patient prematurely based on misapplication of guidelines, or treating a patient for a suspected pneumonia when the patient was misdiagnosed and actually has a pulmonary embolism).

Figure 14-2. Types of Error

It is important to differentiate errors (slip, lapse, or mistake) from violations.

• Violations are deliberate actions, whereby someone does something and knows it to be against the rules (e.g., deliberately failing to follow proper procedures). A health care professional may consider that a violation is well-intentioned; however, it would still technically constitute a “violation” rather than an error. For example, a physician may decide to forgo entering a patient’s allergies into the electronic record due to time constraints in starting treatment. If this act led to an adverse medication reaction due to a missed allergic reaction, it would technically be considered a violation and not an error.

Errors may result in adverse events or near-misses.

• Adverse events are harms or injuries that result directly from medical care, not from negative outcomes due to the patient’s disease or medical condition.
• Near-misses are errors that occur but do not result in injury or harm to patients because they are caught in time or simply because of luck.

Diagnostic errors account for at least 17% of preventable errors in hospitalized patients. Diagnostic errors can be categorized as no-fault, system-related, and cognitive.

• No-fault errors may happen when there are masked or unusual symptoms of a disease, or when a patient has not fully cooperated in care.
• System-related errors include technical failure, equipment problems, and organizational flaws.
• Cognitive errors frequently result from a diagnosis that was wrong, missed, or unintentionally delayed due to clinician error.

The following are examples of common cognitive errors.

A wrong diagnosis may occur when the clinician holds on to a particular diagnosis (usually the initial one, in a phenomenon called anchoring bias) and becomes dismissive to signs and symptoms pointing to another diagnosis. For example, a 65-year-old man presents with epigastric pain and emesis, and he sits leaning forward. He has a history of alcoholism. The patient is likely to be diagnosed with pancreatitis. However, holding on to this diagnosis to the exclusion of any other diagnosis—despite the patient’s denial of alcohol use for several years, normal blood levels of pancreatic enzymes, and abnormal EKG which is ignored—would be an anchoring error.

Confirmation bias, looking for evidence to support a pre-conceived opinion, rather than looking for evidence that refutes it or provides greater support to an alternative diagnosis, may accompany an anchoring error. Clinicians should regard conflicting data as evidence for the need to continue to seek the true diagnosis (e.g., in the case above; acute MI) rather than as anomalies to be disregarded.

Availability bias is the tendency to assume a diagnosis based on recent patient encounters or memorable cases (i.e., the most cognitively “available” diagnosis).

It is estimated that thousands of hospitalized patients die every year due to diagnostic errors. Missed or delayed diagnoses (particularly of cancer) are a prominent reason for malpractice claims. Poor teamwork/communication between clinicians and a lack of reliable systems for common outpatient clinical situations (e.g., triaging acutely ill patients by telephone and following up on test results) have been identified as predisposing factors for diagnostic error.

Recall Question

1. Which of the following is an example of poor workplace conditions?

   1. Overworked staff
   2. Lack of safety protocols
   3. Lack of supervision
   4. Physician fatigue
   5. All of the above

Answer: E