time trade-off (TTO)

A method for determining preference between two health states for different lengths of time, to estimate how many years of life a person is prepared to sacrifice to improve his/her health status.

Note: For chronic states, the options are the reference health state for time t followed by death, or perfect health for a shorter time followed by death. For temporary states, the options are the reference health state for time t followed by an explicitly specified outcome (usually health), or a worse health state for a shorter time followed by the same outcome.