Imagine being told you have cancer based on finding a lump on your torso. You proceed onwards with the course of treatment; chemotherapy and nearly die from it. Just to find out you don’t have cancer after all but rather panniculitis (skin inflammation of fat cells) and all you needed was antibiotics to treat it.
That is how Trisha Torrey felt, after being told she only had a short while to live. Luckily for her, she sensed something was not right because she had no other symptoms except for hot flashes, which could be attributed to menopause (she was 52), and decided to get a second opinion as well as do her own research. Unfortunately, misdiagnosis like this happens quite often. In fact, Trisha is not the first person thought to have cancer only to be an illness that has a simple and easy cure. She was lucky, however, others in the same situation are not as fortunate. There are people who get diagnosed with cancer, undergo chemotherapy and die, only for an autopsy to reveal that they never had cancer to begin with (plus side, the families won a lot of money from law suits). This happens more frequently than we realize. Although
Availability bias is what influences people to overestimate the probability of events associated with memorable or vivid events (Schmidt, Mamede, Van, Van Gog, Van Saase, Jan, & Rikers, 2014). Because memorable events are further intensified by media coverage, we believe it to be more frequent and common. So when we see or hear things that may share similarities with something we perceive to be common, we are more likely to judge that new information to be the same as the information already in our minds. This idea was the bases of Schmidt and colleagues (2014) study on whether exposure to media reported diseases could bias doctors’ diagnoses and cause them to use that information, leading to diagnostic mistakes. The study instructed 38 doctors to evaluate the accuracy of two diseases (legionnaires disease and q fever) found on wikipedia. Six hours later the doctors were asked to diagnose 8 cases (all had different diagnosis, however, two had similar symptoms to the two wikipedia entries). What they found was that, the doctors misdiagnosed cases with similar symptoms to the two wikipedia diseases more frequently when they had read the wikipedia information similar to that disease. However, because their decision were not based on analytical reasoning, when the doctors were given 4 of the 6 cases (2 were the previously misdiagnosed cases with symptoms similar to the wikipedia diseases) and were able to reflect on the case studies, the accuracy of the diagnosis of the 2 cases influenced by the media exposure improved.
What this study essentially says is that availability bias can emerge from a doctor’s exposure to information about diseases in the media. For example; when there is a disease outbreak, and there is lots of media coverage on it (e.g. the Ebola crisis happening right now), it is more likely to come to mind when we see similar symptoms. This information while diagnosing patients, could be used by doctors unconsciously to make diagnostic errors especially when they have some shared symptoms.
Why do doctors succumb to this bias?
An explanation by Schmidt et al., (2014) is that it could have an evolutionary standpoint. We look for similarities to make easy and quick decisions in our environment. As well, it could be how our memory works; how we think. This is called a top down process; we look for similarities, cues in our environment and memories that will help us understand and make sense of our surroundings. The downfall of this is that our memory treats indirect events in the same way as it would treat events actually experienced by us. Our memory can be deceitful, it makes these impersonal events available to us when something similar is encountered. This idea is called pattern recognition, and is often used by doctors when making a diagnosis. Doctors diagnose diseases in an automatic way, through recognition of patterns between the current case and previous cases of patients. This type of reasoning according to Schmidt et al., (2014) is fast, requires little effort, and is only effective in common illnesses like the common cold or flu.
The authors found that when the doctors were given time to reflect on each case separately and to look at the symptoms individually, the accuracy of their diagnosis improved. This suggests that, if the doctors are able to reflect, and critically assess each case on it’s own there would be less room for diagnostic mistakes. Even with this, one must keep in mind that medicine is based on trial and error. It is far from being a perfect science and this applies to the wonderful people who practice this flawed science. Even when reflection is done on their part, there is still a chance of mistakes happening.
So then what can you the patient do?
Firstly, no, you cannot disregard everything your doctors tell you.
What you can do is:
- Be cautious: pay attention when the doctor goes over your diagnosis with you.
- If there is something that doesn’t make sense to you, ask for clarification.
- Do your own research to learn more about your diagnosis (note: reading something online does not equate to actual professional opinion).
- When in doubt seek multiple opinions, after all, the worst that could happen is that they tell you what you already know.
References
Schmidt, H. G., Mamede, S., van, d. B., van Gog, T., van Saase, Jan L. C. M., & Rikers, R. M. J. P. (2014). Exposure to media information about a disease can cause doctors to misdiagnose similar-looking clinical cases. Academic Medicine, 89(2), 285-291. doi:http://dx.doi.org/10.1097/ACM.0000000000000107
Torrey, T. (2014). A storey of misdiagnosis: how a wrong diagnosis became a source of motivation. Retrieved fromhttp://patients.about.com/od/yourdiagnosis/a/How-Common-Is-Misdiagnosis-Or-Missed-Diagnosis.htm
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