On assisted dying, are we really any good at predicting survival?

Forecasting the last seven days of life is harder than the final 24 hours; beyond that, things become shakier still.

- Anjana Ahuja

On Nov 29, the British Parliament will vote on whether terminally ill individuals with mental capacity can ask for medical help to hasten death. If the assisted dying Bill passes, Britain will move closer towards sanctioning state-assisted suicide, bringing it in line with countries such as Switzerland, Belgium and Canada.

There are compelling arguments on both sides of this emotive issue, and the result feels impossible to call. While public opinion broadly supports change, parliamentarians seem more divided.

But one aspect has been overlooked: the science of predicting survival. As a safeguard, the Bill restricts the right to assisted dying to those with less than six months left to live. While ballpark estimates of survival can be calculated using patient groups, forecasts for individuals are harder to pin down.

"My research demonstrates that there is no reliable way to identify patients with less than six, or 12, months to live—at least, no method that would be reliable enough to act as any sort of 'safeguard' for the proposed assisted dying legislation," emeritus professor Paddy Stone, a former head of the Marie Curie palliative care research department at University College London, told me this week.