It might be the most difficult question a patient will ask a health care provider: "How long do I have to live?"

Last Tuesday, I wrote about how clinicians struggle with maintaining "rational" hope in seriously ill individuals while being open and honest and allowing them to make difficult personal choices.

The next day, The New England Journal of Medicine published a set of guidelines about how to respond when elderly or terminally ill patients wonder when they should expect to die.

Prognosis — the science of predicting how long a patient will live — is complex because predictions about medical outcomes are always uncertain, note researchers at the University of California, San Francisco, and the University of Pittsburgh.

"On the one hand," says Alexander K. Smith, M.D., assistant professor of medicine in the UCSF Division of Geriatrics, physicians "should not use uncertainty as an excuse to avoid the conversation entirely. On the other hand, how should they help patients to deal with uncertain information, given that uncertainty tends to produce so much anxiety in patients?"

Among the guidelines recommended by Smith and his co-authors:

  1. Acknowledge that, much like the weather, it is difficult to make certain predictions.
  2. Respond to a patient's emotional reactions to uncertainty and address concerns about what the future may bring.
  3. Help patients focus on living in the present so that patients and their families aren't stuck dwelling on an uncertain future that may be terrifying to them.

When a patient presses the issue, Smith tells them, "I could pick a date, but I can guarantee that I would be wrong." Instead, when he gives a prognosis, Smith often says days to weeks, weeks to months or months to years. "Acknowledging uncertainty is part of the prediction," he says.

Read more about the guidelines.