In the work world and in life, confidence is a highly appealing trait. But when it goes overboard, it can be dangerous—especially when it’s a doctor who is wielding an infallible, all-knowing attitude.

A growing body of evidence suggests that diagnostic errors—diagnoses that are missed, wrong or delayed—may cause as much death and disability as all other types of medical errors combined. And a common cause of these errors, research shows, is an overconfident doctor. 

Sobering study: To understand how doctors’ confidence levels sync up with their accuracy in diagnosing medical conditions, 118 internal medicine doctors in the US were given diagnostic cases to solve online—two that were easy and two that were difficult. The doctors were given the patients’ medical profiles (histories, physical exams and diagnostic tests) and could ask for additional resources if they needed help. The doctors got the right diagnosis in 55% of the easy cases, but in only 5.8% of the hard ones, according to the research, which was published in JAMA Internal Medicine

The doctors then were asked to rate their confidence level for each diagnosis on a scale of zero to 10. For the easy cases, the average confidence level was just over seven. For the hard ones—the ones they got right only 5.8% of the time—the confidence level averaged 6.4, hardly dropping at all. 

To learn how physician overconfidence can contribute to diagnostic errors, Bottom Line Health spoke with David E. Newman-Toker, MD, PhD, a leading expert in patient safety.

How does doctor overconfidence contribute to diagnostic error? There is a lot of research showing that people who have the highest confidence levels are less competent than their peers who are a little less confident. So having a little uncertainty is a good thing—you’re less likely to assume that you’re right, and it gives you some motivation to learn and improve. This is now being recognized in medical schools and residency programs. In the past, confidence and quick decisions were valued in medical training. Today, there is more of an emphasis on a willingness to express uncertainty. Doctors who get more help and more information become better doctors. 

We can think of overconfidence as a special type of “cognitive bias” that makes us unaware of the risk we might be wrong. Bias happens to everyone—all people rely on past experience to make new decisions, and our brains often take “shortcuts” or go on “autopilot.” But this can be a trap for doctors with years of medical experience. They may substitute past experience for critical thinking and that can be dangerous.

What other factors can lead to overconfidence? The biggest issue in overconfidence is a lack of feedback. When a doctor makes the right diagnosis, the patient comes back and gives thanks and praise. When a doctor makes the wrong diagnosis, however, the patient often moves on to another doctor, and the first doctor never finds out.

For an emergency room (ER) doctor, overconfidence could be a factor when he/she, say, orders a CT scan for a patient with new dizziness to rule out a stroke. If the scan is normal, the ER doc may confidently dismiss it—and miss the diagnosis of stroke. A neurologist would know that an early CT scan (especially in the first 24 hours after symptoms begin) will miss at least 85% of the most common type of stroke, the type caused by a blood clot in the brain. An MRI would miss only about 15% to 20%. The ER doctor may have been overconfident because he did not know what he didn’t know. 

How can you spot an overconfident doctor and protect yourself from a medical mistake? The three most important things patients can do is come prepared…ask the right questions…and stay vigilant. When you have a new problem…

Write down all of your symptoms on a sheet of paper in the order they happened—make a timeline if you can. Take your time and include all the things that could be important. Giving your doctor a good starting point saves time and helps your doctor focus on your problem. 

Write down key questions to ask. If your doctor gives you a diagnosis, ask what else could be causing your symptoms. Ask what your doctor is most worried about. What is the worst thing that could be causing your symptoms? Why does your doctor think that condition is not the problem? 

Stay vigilant. If your doctor starts treatment and you are not getting better, don’t assume it’s just the wrong medication. It could be the right medication for the wrong diagnosis. Instead of accepting a change in medication or a higher dose, it’s OK to question the diagnosis. Don’t be afraid to ask for a consult with a specialist or a second opinion. If the doctor seems upset when you ask questions or the treatment being proposed is risky, consider getting that second opinion even before starting treatment. 

Some situations are riskier and more error-prone than others. High-risk situations occur, for example, when your doctor is really busy and seems to be in a hurry…if you’ve been seen multiple times for the same symptoms without a clear diagnosis being made…and if your symptoms are new and serious enough that you’ve gone to the ER.

Finally, look out for overconfidence “red flags.” If your doctor does not give you enough time, does not listen to your questions or gets in a huff when you ask for a consult or second opinion, get another doctor. If you do find out that your doctor made a mistake, let him/her know. That type of feedback may help your doctor avoid the overconfidence trap in the future.