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May 13, 2015

Could you be making a diagnostic error? How to avoid Cognitive Bias

autopsy1-resized-173Diagnosis is the first and most important decision made about a patient - it determines all subsequent treatment and determines the course of each patient encounter. How well this decision is made, therefore, is one of the most significant measurements of healthcare quality and efficiency.

Despite this, misdiagnosis, is everywhere. It accounts for 30-40% of all malpractice claims in the industry and about 2/3 of all claims in primary care. Moreover, diagnostic errors are frequently the leading or second leading cause of malpractice claims in the United States, accounting for twice as many alleged and settled claims as medication errors.

Some diagnostic errors are caused by a breakdown in the system, such as test results being misplaced or not received by the physician - something that could be helped by introducing more health technologies like personal, connected health records into the medical environment. Most mistakes, however, come down to the mind of the physician, and the processes they take to arrive at a diagnosis. Physicians can fall short of their own experience, or simply not take on all options available.


Premature Closure

There is now a large body of work describing the many biases that we, as human beings and not just clinicians, are prone to. The most prevalent of these in diagnostic errors is “Premature Closure.” As Dr. Mark Graber described in his landmark paper, “Diagnostic error in internal medicine,” this is where the clinician decides on a diagnosis very quickly, but then fails to consider other reasonable possibilities until it is too late. In any analysis of cases where the diagnosis was delayed or missed, premature closure has been the most common contributing bias.

Cognitive De-biasing

One of the proposed solutions to this cognitive bias problem is termed “cognitive de-biasing.” In a nutshell this means the physician is made aware of the potential bias they may form when deciding on a diagnosis, and therefore avoids the bias by exploring further options. And how do they explore these options?

Differential Diagnosis

The concept and practise of a comprehensive differential diagnosis has been taught for over 100 years, but it is not used routinely in medicine. One of the main reasons for this is the time it takes to construct one. Due to a lack of time in the ED or primary care, for example, many clinicians rely on their memory to construct a differential - the bias kicks in and you’re back where you started. There are approximately 200-300 diseases that come up in primary care. Compare this to a total universe of about 12,000 diseases and it is possible and even obvious that, on occasion, a clinician will simply not think of a diagnosis either because he did not remember it or never knew it in the first place.

If there is diagnostic doubt, the clinician then typically has to consult with colleagues, read textbooks or research online in order to investigate further and come up with a feasible answer. With medical textbooks and online reference resources, it’s very difficult to search for something when you don’t know what you’re looking for. A search for “toxic shock,” for example, will provide huge amounts of information, but if you are unsure and just know that the patient has ankle pain, ankle edema, diarrhea and fever, then the traditional reference resources are not very helpful in connecting and making sense of all of these signs and symptoms.

That’s where tools like Isabel can help. When more complex clinical presentations come up, a diagnostic tool or aid can give you a list of possible diagnoses from symptoms input by the physician. Using such a tool could be the difference between an unexplored misdiagnosis made with a cognitive bias, and a well thought out diagnosis taken from a credible differential. And the best part - differential diagnosis tools work in seconds. No searching through book after book and emailing colleagues past and present in the hope someone will come up with an answer - any answer - quickly. The tool’s job is to get the clinician thinking about a disease that he had not thought about previously by giving you a list of all possibilities, right there and then.

This is an excerpt from our whitepaper: "Why and How to Improve Diagnostic Decision Making." Download the full whitepaper here:

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Jason Maude

Jason Maude

Jason is the CEO and Co-founder of Isabel. Prior to co-founding Isabel, Jason spent 12 years working in finance and investment banking across Europe. His daughter, Isabel, fell seriously ill following a misdiagnosis in 1999 and this experience inspired Jason to abandon his city career and create Isabel Healthcare Ltd.


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