The time trade-off (TTO) is a choice-based method of eliciting health state utility, which reflects the length of remaining life expectancy that a person may be prepared to trade-off in order to avoid remaining in a sub-perfect health state.  The TTO method usually involves asking the respondent to consider remaining in a specified health state (‘Health State A’) for the next 10 years, and then to die without pain.  The respondent is then asked how many years he or she would need to live in full health (and then dying without pain) to make this option exactly as desirable as being in Health State A for 10 years.  Typically, the answer will be a value less than 10 years.  If, for example, the respondent answers that 8 years in full health would be required, then it is inferred that the being in Health State A has 80% of the utility of being in full health (i.e. it has a utility value of 0.8), since both options would then provide exactly 8 QALYs.  A limitation of this method is the fact that people do not always value health in future years the same as health at the current time.  In order to allow for this, discount rates are applied to QALYs in economic evaluations to adjust the value of future health benefits.  However, because it is impossible to calculate the exact rate at which each individual will discount, the adjustments cannot be relied upon to be an exact reflection of their true preferences.

 

How to cite: Time Trade-Off [online]. (2016). York; York Health Economics Consortium; 2016. https://yhec.co.uk/glossary/time-trade-off/