Don't raise false hope or misrepresent the risks of medical care

Here's one more probability: When a patient is surprised and upset by a treatment failure or complication, he may sue you, even though you're not at fault.

That's all the more reason to carefully approach informed consent, that exam room ritual of securing a patient's permission for a test or treatment after discussing its benefits, risks, and alternative measures. If you help a patient form reasonable expectations about a course of action, he's not only in a better position to say Yes or No, but he's also less likely to legally retaliate when medical results are less than perfect, says San Francisco GP and JD Dan Tennenhouse, co-author of Risk Prevention Skills for Physicians.

To help you avoid this debacle, we've identified ways that doctors inadvertently lead patients to expect too much from proposed treatment, as well as stratagems to set patients straight.

Odd beliefs about odds, and other challenges

"The risk of this complication is low, Mrs. Jones."

That sounds like good informed consent, doesn't it? Unfortunately, what you mean by "low" and what Mrs. Jones means by "low" may be two different things, says John Paling, educator and author of Helping Patients Understand Risks. "A doctor performing a kidney transplant may think that odds of 1 in 100 for a complication represent a low risk, while a patient may think they're huge."

Paling preaches the importance of establishing common linguistic ground. He suggests that doctors peg risk descriptors to a range of odds; such as 1 in 1,000 to 1 in 10,000 for "low" and 1 in 100,000 to 1 in a million for "minimal." Doctors, in turn, could share these standards with patients.

Descriptive words alone aren't sufficient for informed consent, he says, and should be complemented by some statistical expressions of risk. That's familiar territory for doctors who are taught to think like scientists. How-ever, patients may be less well-schooled, so doctors must guard against statistical misunderstandings, too, says Paling.

"If you tell patients the odds of Complication A are 1 in 250 and the odds of Complication B are 1 in 25, many will view the second complication as less likely, because the denominator is lower," says Paling. Always compare risks in terms of a common denominator-4 in 1,000 versus 40 in 1,000, for example.