Patients may be more likely to be misdiagnosed if they are considered ‘difficult' by their doctor, a new study indicates.

It has been widely suggested that the accuracy of a diagnosis may be adversely affected if a patient is considered difficult, but until now, there has been no evidence to back this up. Dutch researchers decided to investigate further.

They provided 63 doctors who were in their last year of specialty training in family medicine with one of two versions of six different clinical case scenarios. In each of the cases, one of the patients was considered difficult, while the other was considered neutral, i.e. they did not display any disruptive behaviour.

The difficult patients included one who was aggressive, one who was demanding and one who questioned the doctor's competence. The six conditions included appendicitis, pneumonia and a blood clot in the lung (pulmonary embolism).

The doctors assessed the patients and also rated their likeability using a recognised scale.

As expected, the doctors were more accurate when they were diagnosing simpler cases, although they were 6% more likely to misdiagnose difficult patients presenting with simple cases. However, when it came to more complex cases, such as appendicitis, the doctors were 42% more likely to misdiagnose a patient if they were difficult.

These findings stood irrespective of the time spent on the diagnosis. The researchers believe that the mental effort needed to deal with disruptive behaviours distracts doctors from the job at hand, making it harder for them to process the clinical information properly.

In a second study, 74 trainee hospital doctors were asked to diagnose eight clinical case scenarios. Half of these involved neutral behaviours, while half involved difficult behaviours, including accusing the doctor of discrimination and threatening the doctor.

After making a diagnosis, the doctors were then asked to recall the clinical findings and behaviour of their patients.

This study found that diagnostic accuracy was 20% lower for difficult patients, even though the time spent reaching the diagnosis was around the same. The doctors also tended to recall slightly fewer clinical findings in the disruptive patients.

The researchers again believe that the mental energy required to deal with disruptive patients adversely affects the way in which doctors process clinical information.

They said that while most people feel that doctors should be above reacting in this way, ‘the fact is that difficult patients trigger reactions that may intrude with reasoning, adversely affect judgements and cause errors'.

Details of these findings are published in the journal, BMJ Quality & Safety.