Evidence-appraisal glossary
Restricted Mean Survival Time
The average event-free time a group accumulates up to a chosen cutoff, found by measuring the area under the survival curve out to that time point. It expresses survival results in plain units like months rather than as a ratio.
Also called: RMST, restricted mean survival.
RMST answers a concrete question: on average, how much extra event-free time did treatment buy over the follow-up window? It does not require the proportional-hazards assumption, so it stays interpretable even when survival curves cross or bend. Because it reports a difference in time, readers can weigh benefit against burden more directly than a hazard ratio allows. The chosen cutoff, called the restriction time, shapes the answer, so trials should fix it in advance.
This is a plain-language methodology definition for reading research. It is general education, not medical advice.