Discounting life-years: whither time preference?

If elicited time preferences are to be incorporated into economic evaluations, not only social but also individual preferences may be included. The view of this paper is that social intertemporal preferences should govern social intertemporal choices when prioritising between the saving of lives now or in the future. However, the present value of an individual's stream of future health benefits is a matter of private consumption and hence either individual time preferences or social interpersonal preferences could be applied when evaluating the value of extended life or improved quality of life. This paper shows that it is possible to incorporate both types of time preferences in an economic evaluation; using the individual time preference or the social interpersonal preference when discounting the remaining life expectancy and the social intertemporal time preference for discounting the health benefits from the time of the risk reduction to present time. Such a scenario could solve potential problems such as double discounting of QALYs, the paradox of intertemporal equity versus interpersonal equity, as well as include elements of quantity, risk and uncertainty which are otherwise ignored in evaluations of life-saving therapies.