Introduction

In medicine, decisions have to be made between alternative courses of action: how to treat a particular patient, say, or how to allocate resources nationally between different specialities. Qalys (quality-adjusted life years) are intended to help in this sort of decision making.

Specifically, they are intended to measure the benefit – or the good, as I shall say – that will result from each of the alternatives. The idea is that the benefit of a course of action is the extra years of life it gives people, adjusted for quality; better years count more than worse ones. In medical decisions, benefit is obviously an important consideration, but it is often not the only one. Another is fairness: when treatment is to be given to some patients and denied to others, to treat those whose treatment would do the most good is not necessarily the fairest thing to do. Other things being equal, for instance, treating a younger person is likely to do more good in total than treating an older one, because the younger has longer to enjoy the benefits. But if resources are concentrated on the young for this reason, that may be unfair to the old. So benefit and fairness may conflict.

Qalys are concerned only with benefit. Consequently, they cannot entirely determine which decision is the right one. The friends of qalys have not always acknowledged this limitation, and this has exposed qalys unnecessarily to attacks from their enemies. The main objection raised against them is that their use is unfair. Qalys certainly do not take account of fairness; they cannot be expected to. Fairness must be considered separately. Nevertheless, benefit is plainly important, so qalys have an important role open to them.