Are you raising false hopes?

Key Points

Medicine is all about probabilities-the probability of a calcium channel blocker averting a stroke, of a Pap smear detecting abnormal cells, of a Botox injection making it difficult to swallow.

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. However, 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 vs 40 in 1,000, for example.

Likewise, put expressions of relative risk such as "Drug XYZ reduces the chances of such and such disease by 50 percent" into context, he says. A patient may find this benefit compelling, but for a better understanding, he also needs to hear about the absolute risk. How many people in 10,000 normally contract the disease when untreated, and how many do so on the medication? Let's assume the medication reduces the number from 2 in 10,000 to 1 in 10,000. A patient may have second thoughts about taking it, particularly if it comes with a high risk of debilitating side effects.