Misdiagnosing patients' preferences for their care may be less obvious than misdiagnosing disease, but the consequences for the patient can be just as severe, a new study warns.

Because doctors are rarely made aware of an erroneous care preference diagnosis, it could be called "the silent misdiagnosis," says the study, published by health policy think tank The King's Fund. But the NHS must break this silence, and when it does so it will score three distinct victories, according to authors Al Mulley, Chris Trimble and Glyn Elwyn.

The first victory will be that patients, who can suffer just as much from a preference misdiagnosis as a medical one, will get the medicine they would choose if they were well-informed - that is, if they had better information about treatment options, outcomes and evidence, say the authors.

Second, the NHS's aspiration to create an "internal market" will finally have a chance to active its full potential and, third, because patients choose fewer treatments when they are fully informed, the NHS could save billions of pounds, they add.

The problem of the silent misdiagnosis is widespread, the study finds. There are wide gaps between what patients want and what doctors think patients want, and there are also dramatic geographic variations in care that can only partially be explained by causes other than the silent misdiagnosis. Moreover, research shows that patients choose different treatments after they become better informed. 

The most important step which the NHS needs to take to deal with this issue is to measure and report the incidence of preference misdiagnoses, the authors recommend. The Service also needs to challenge a number of what they describe as "entrenched but erroneous assumptions that are inconsistent with the mindset necessary to tackle the problem of the silent misdiagnosis." These assumptions are: - that science alone determines need; - that variation in care is the problem; - that patient choice is about time and location; - that “the market" can sort out health care; and - that commissioners can calculate need.

The NHS also needs to support doctors by providing them with more and better information about what patients want, and by providing patients with more and better information about options, outcomes and evidence. And, to assess progress, the Service should implement measures that indicate how much doctors and patients have learned, say the authors.