By way of background: "QALYs", or Quality-Adjusted Life Years, are self-explanatory. "DALYs", or Disability-Adjusted Life Years, sound like they should be the same thing but (confusingly) also build in an instrumental component, discounting the "unproductive" years of the very young and elderly in favour of the (young-ish) working-age population.
Persad et al. criticize the DALY system on the grounds that "DALY allocation wrongly incorporates age into the outcome measure, claiming that a year for a younger person is in itself more valuable. Priority for young people is better justified on grounds of distributive justice." (428)
I find this criticism confusing. Firstly, at least as they describe it, the DALY system is explicitly based on the idea that a working-aged life-year is instrumentally rather than "in itself" more valuable. Is this "wrong"? It seems factually plausible, though one could reasonably ask whether such non-medical factors should enter into medical decision-making at all. (In principle, it certainly seems reasonable to prefer that public resources go to help as many people as possible, whether directly or indirectly. But such a policy might have a high risk of poor implementation or other unintended consequences, rendering it unwise to implement in practice. I remain agnostic on the practical question -- the answer's not obvious to me either way.)
Moreover, it seems extremely plausible that some years of life are intrinsically more valuable for us than others. (I previously noted this as a respect in which QALYs are insufficiently discriminating.) Persad et al seem to recognize this, at least implicitly, when they explain how their own view would take age into account. After noting a general principle of favouring the young on prioritarian grounds (they haven't yet had a "fair innings"), they add:
Consideration of the importance of complete lives also supports modifying the youngest-first principle by prioritising adolescents and young adults over infants... [A]dolescence brings with it a developed personality capable of forming and valuing long-term plans whose fulfilment requires a complete life. As the legal philosopher Ronald Dworkin argues, “It is terrible when an infant dies, but worse, most people think, when a three-year-old child dies and worse still when an adolescent does”
Here, intuitively, the adolescent's death is worse for his own sake -- a datum that may be explained by the fact that he has a developed personality, would have thwarted plans and projects, etc., in contrast to a cognitively undeveloped infant with nothing yet to lose. But I would similarly argue that the twenty years of life from age 15 - 35 are likely of greater value to the individual than the twenty years from 70 - 90. After all, the former span is likely to involve much more experiential diversity, is more central to the development of one's values and sense of self, and may also involve more central life projects (from relationships to career choices) than one is likely to be undertaking in very old age. In short: The former twenty years are utterly transformative. The same can't be said of the latter. They may still be very valuable, to be sure; but they can't compare to the significance of more transformative decades of life. I think our intuitions reflect this: A life cut short at 70 rather than 90 seems not as radically and detrimentally truncated as one that's cut short at 15 rather than 35, even though the same number of life-years are at stake in either case.
So while Persad et al. object that "DALY allocation treats life-years given to elderly or disabled people as objectively less valuable", in fact this seems like a point in favour of the view. It's simply true that those life-years are less valuable, both instrumentally and in terms of welfare value: the value of those years to the individual who would live them.
If anything, the "Complete Life" perspective should help us to appreciate this fact. When we look at our lives as a whole, we can see that some periods are more centrally important than others. It's vitally important (for one's welfare) to live a full, complete life. It's a nice bonus, but ultimately less important, to achieve additional life-extension beyond what is necessary to live a "complete life". This isn't just a matter of distributive justice, as Persad et al seem to think. It's a fact about welfare, or the value of the life(-year) for the person living it.
(But I do wish we had a less misleading name than "DALYs" for including age-based adjustments. Something like "Welfare-Adjusted Life Years" would make more sense!)
* Persad G, Wertheimer A, & Emanuel EJ. (2009) 'Principles for allocation of scarce medical interventions' Lancet 373(9661): 423-31.