Diagnostic biases


how-doctors-think_cover_imageIn a previous post I discussed the widespread, and, in my case, unwitting, use of heuristics in clinical decision making. The advantages of heuristics, such as managing complexity and improving efficiency are well documented but equally they can be a disadvantage by leading to faulty reasoning and conclusions1.  One disadvantage is that they can contribute to cognitive bias in clinical decision making. Cognitive bias is defined as a pattern of deviation in judgment, whereby inferences of other people and situations may be drawn in an illogical fashion2. Several important cognitive biases deriving from heuristics are discussed in Jerome Groopman’s book ‘How Doctors Think’3. Some of the more common are:

The availability bias – ‘the tendency to judge the likelihood of an event by the ease with which relevant examples come to mind.’3 (p.64) An example could be that having seen several cases of kennel cough recently, a cough due to heart disease may be misdiagnosed as the veterinarian recalls quickly the current outbreak of kennel cough.

The anchoring bias – the ‘tendency to perceptually fixate on to the salient features in the patient’s initial presentation at an early point of the diagnostic process and failing to adjust initial impressions even in the light of later information’4

The confirmation bias – related to the anchoring bias, this refers to the tendency to look for confirming evidence to support the diagnosis we are “anchoring” to, while downplaying or ignoring information that might contradict the initial diagnosis.

The satisfaction of search bias – the tendency to stop looking for alternate or even coexisting diagnoses when we have made one diagnosis. A classic example of this is not searching for a second fracture once “sufficiently satisfied” with finding the first fracture5.

Many vets, particularly more recent graduates, worry that they won’t have sufficient knowledge of clinical disease but in fact the vast bulk of diagnostic errors come from cognitive mistakes6. Reflection on the clinical evidence available is a recommended way of limiting errors due to faulty clinical reseasoning7. Core questions include:

  • Why do I favour this diagnosis?
  • What else could it be?
  • Could two things be going on?
  • Have I considered the finding or lab result that doesn’t quite fit?7

Awareness of these potential errors is a great step towards reducing the chance of falling into the common traps.

Beside the scientific basis of clinical error, mistakes can have significant impact, obviously on the patient, but also on the clinician. Media coverage and complaints processes rightly concentrate on the former, while the failure to discuss the latter can be devastating to the people involved. As a clinician who has made mistakes, my next post will discuss the culture around clinical error.

1. Elstein, AS., 1999. Heuristics and Biases: Selected Errors in Clinical Reasoning. Academic medicine, 74 (7), 791-4

2. Cognitive bias – Wikipedia, the free encyclopedia. 2013. Cognitive bias – Wikipedia, the free encyclopedia. Available at: http://en.wikipedia.org/wiki/Cognitive_bias. [Accessed February 10, 2014].

3. Groopman, J., 2007. How Doctors Think. Houghton Mifflin, Boston

4. Emergency Medicine Blog: Heuristics and Cognitive Biases in Decision Making During Clinical Emergencies. 2013. Emergency Medicine Blog: Heuristics and Cognitive Biases in Decision Making During Clinical Emergencies. Available at: http://emergencymedic.blogspot.com.au/2012/01/heuristics-and-cognitive-biases-in.html [Accessed 30 August 2013].

5. Croskerry, P., 2009. A Universal Model of Diagnostic Reasoning. Academic Medicine, 84(8), pp.1022–1028.

6. Croskerry, P., 2003. Cognitive Forcing Strategies in Clinical Decision making. Annals of Emergency Medicine, 41(1), pp.110–120. Available at: http://home.comcast.net/~jasoncillo/Cognitive.pdf [Accessed February 10, 2014].

7. Misbah Keen University of Washington School of Medicine, 2013. Medical Decision Making in Clinical Care: Avoiding Common Errors. Available at: http://healthinfo.montana.edu/WWAMI Conference/Medical Decision Making 2013-04.pdf [Accessed February 10, 2014].


About rebekahmcbrown

I am a veterinarian with a special interest in instructional design and developing eLearning in the veterinary and medical areas. I write teaching materials for both face-to-face and online learning as well as writing and editing articles.
This entry was posted in Uncategorized. Bookmark the permalink.

One Response to Diagnostic biases

  1. Pingback: I’ve made mistakes in veterinary practice. Have you? | Rebekah Brown

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s