All-cause mortality

All-cause mortality is the risk of death from any cause over a given period. Health studies often report how a factor — fitness, a habit, a biomarker — relates to it, because it sidesteps the problem of one risk simply shifting deaths from one disease to another.

It matters because a factor linked to lower all-cause mortality is genuinely associated with living longer overall, not just avoiding one specific illness. Cardiorespiratory fitness, strength and not smoking show some of the strongest such links.

In practice, when you read that something is 'associated with lower all-cause mortality', it means people with more of it tended to live longer — though association isn't proof of cause, and context matters.