disability-free survival

Staying alive and staying well are not the same thing, and a trial that counts only deaths cannot tell them apart. Disability-free survival is the measure researchers reach for when the question is whether a treatment adds good years rather than simply more years. It folds three events into a single outcome: death from any cause, dementia, and persistent physical disability. A participant who reaches any one of the three has reached the endpoint.

The measure was defined in this form by the ASPREE trial, which tested daily low-dose aspirin in 19,114 community-dwelling adults aged 70 and over in Australia and the United States. Its investigators derived the composite from those three components and described it as a way to reflect a healthy life span, so that a drug's benefits and its harms could be weighed together in one number rather than argued over separately.

Because it bundles three very different events, disability-free survival is a demanding thing to shift. A treatment can cut heart attacks sharply and still leave it unmoved, since heart attacks are only one of many roads to death, dementia or disability. That outcome is a real answer to a real question, not a failure of the trial.