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Anchoring: Its Role in Diagnostic Error

blog_Anchoring_CognitiveErrorsintheFailuretoDiagnose_260x200[8 MIN READ]

Why was the diagnosis really missed?

In my previous position as Manager of Risk, Claims & Insurance for our physician group, the available methods of error analysis never satisfied my quest for the ultimate answer to this recurring question in any given case. The majority of our group practice was emergency medicine; our claims data mirrored the national trends showing that most claims were related to diagnostic error, which contained the allegation that a clinician was negligent by either not making the diagnosis in a timely fashion or failing to make the diagnosis entirely.

Diagnostic Error & Malpractice

What data do we have to show that diagnostic error is even a problem? Closed claims data from 3 large malpractice insurance companies show that diagnostic error is the underlying cause of at least 50% of malpractice claims. This number varies widely from specialty to specialty. In nearly all medical specialties (emergency medicine, internal & family medicine, pediatrics, etc.), getting to the right diagnosis is the Holy Grail. Our patients present with a complex of symptoms, and we strive to arrive at an explanation of the problem – rapidly, accurately and within the elusive “standard of care.” The surgical specialties are more concerned with procedures, and while diagnostic errors do occur, they are less common than with the medical specialties. Claims in surgical specialties are dominated by procedure-related issues. Bottom line – if your practice or healthcare service line is more medical than surgical, the risk reduction focus should be on preventing diagnostic errors.

If we fail to diagnose and the result is an adverse outcome, the case is categorized as “diagnosis-related.” I understand the need to categorize the event for insurance purposes, but this taxonomy provides little useful information to clinicians and patients who need to know not only what happened, but how and why. The search for the true root causes of diagnostic error inevitably leads down the path of cognitive errors.

Ask the Question

In a prior blog, I opined that the true origin of an adverse patient outcome may never be discovered for the simple reason that one key question was never asked – What was the practitioner really thinking? When possible, it is worth asking this question along with the other standard inquiries. Very often the answer is there, hidden in the decision-making center of the brain, where the error truly began. Let’s look at a case of delayed diagnosis and the underlying cognitive error responsible for the adverse outcome.

Case: Enemas until Dead

A 78-year-old man presented to the ED with abdominal pain in the mid-lower abdomen for 3 days. He had no fever, vomiting or diarrhea, and had no appetite or bowel movement for several days. A cursory exam by the busy ED physician showed that the patient’s VS were normal and his abdomen was somewhat distended and moderately tender below the umbilicus. There was no guarding, rigidity or rebound. The practitioner ordered enemas for presumed constipation, with no results. More enemas were ordered, and after hours of worsening pain, the nurse noted increasing abdominal distention and tenderness. The clinician ordered an abdominal CT that showed a ruptured sigmoid diverticulum and free enema fluid in the peritoneal space. The patient died days later after surgery and a stormy course.

The Malpractice Case

It is no surprise that this case resulted in a malpractice claim. The allegations included:

  • Failure to consider other diagnoses
  • Delay in ordering appropriate diagnostic studies
  • Failure to re-examine the patient
  • Inappropriate treatment
  • Delay in diagnosis
  • Delay in consultation

The Cognitive Autopsy: Anchoring

For whatever reason, the physician’s thinking locked onto the reported history of “no bowel movement for days.”

This tendency to fixate on certain features of the patient’s presentation too early in the workup is known as anchoring. Anchoring is one of the most common, powerful and problematic cognitive errors found in diagnostic errors.

The term anchoring is appropriate because it describes something that is stuck and immovable. In this case, it was the physician’s thought process that got stuck. Immediately after the initial history and exam, he narrowly focused on the history of “no appetite or bowel movement for days.” Once the anchor of constipation was attached to the patient, it was difficult to remove for several hours. By that time, the anchor had caused irreparable damage.

Think of your own examples of anchors you have attached to certain patients. Be especially aware of the anchors that are assigned to our “frequent flyer” population. This is a high-risk group because of our tendency to not take their complaints seriously or because they are diagnosed as “the migraine,” “the gallbladder,” or “the back pain” even before assessment and testing. Could the migraine be a subarachnoid hemorrhage? Could the gallbladder pain be an acute coronary syndrome? Could the back pain be a thoracic aortic dissection? Caveat: this is not an argument for performing every test on every patient at every visit to rule out every worst-case scenario, but rather an appeal to employ a thorough history, exam, and differential diagnosis tool in order to minimize the effect of anchoring.

Avoid Anchoring to Aid in Diagnostic Error Prevention

Tips to Avoid Common Diagnostic Errors

In retrospect, it is easy to identify anchoring as the chief culprit and cause for diagnostic error in this and most cases. Preventing future errors related to anchoring is more difficult. Here are some practical tips to avoid diagnostic errors and adverse outcomes caused by anchoring.

  • Become aware of the common tendency to jump to a conclusion too early in the evaluation.
  • Consider the first impression as one, but not the only, diagnostic explanation.
  • Gather sufficient supporting information and avoid jumping to conclusions.
  • Use performance appraisal to provide feedback to members of the patient care team.
  • Re-evaluate the diagnosis at critical decision-making points such as admission or discharge.

Delayed or missed diagnoses are responsible for a huge proportion of medical errors today, and they are the major threat to patient safety. Cognitive errors are a primary component of diagnostic error in medicine and diagnosis-related claims. It is imperative for healthcare professionals to become knowledgeable and conversant in the common cognitive errors and the strategies to prevent them.




Categories: Diagnostic Error, Emergency Medicine, Patient Safety, Urgent Care, Medical Error, medical malpractice


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