Any attempt at a more casual dress-down approach appears not to put patients at their ease at all.
And the very worst thing a doctor can wear to undermine their standing with a patient is a nose ring.
They pinpointed four items that help create the right impression with patients, and suggest that doctors wear at least two at any given time:
Twelve general physicians working at John Hunter took part in the study.
Over seven months, each doctor gradually changed their appearance each month.
Six became more and more casual. First, they shed their white coat, then their tie, then changed from smart trousers to flared jeans, and from a smart shirt to an Hawaiian shirt.
Finally, they moussed and highlighted their hair, and inserted a nose ring.
Six others did the opposite, and gradually smartened themselves up.
Questionnaires were sent to 1,680 patients after discharge asking them about their feelings towards their doctors.
Questions included: "Would you buy a used car from this doctor?"
The results showed that while patient confidence was highest with the "respectable" dress protocol, confidence levels did not deteriorate significantly with the loss of the white coat or tie.
But the switch from smart shirt and trousers did send confidence levels plunging.
Part of a package
Writing in the Medical Journal of Australia, the researchers argue that some doctors are so focused on the treatment and advice they give patients, that they give little thought to other matters such as putting people at ease.
They say: "Our results indicate strong contextual effects for the delivery of care, with physicians' dress influencing patient perceptions."
Dr Simon Fradd, chairman of the Doctor-Patient Partnership, said a doctor's appearance was just one factor in helping to create an air of confidence, which in some cases was all that was needed to have a beneficial effect on patients.
"For GPs especially, one is very often not required to give treatment, what one needs to do is to give reassurance, and that requires more than simply saying' there is nothing wrong with you, go away', the patient actually has to believe that."
