Martin Stephens, chief pharmacist, Southampton University Hospitals trust Your debate on quality-adjusted life years as a means to assist resource allocation is welcome (HSJ Debate, pages 20-21, 26 May), but the starkly opposing views of Professor Nick Bosanquet and Sir Michael Rawlins could cause bemusement. They seem to argue from different premises and use contrasting scenarios. I would not accept the bleak picture painted by Professor Bosanquet, but Sir Michael's defence also misleads.

'QALYs are ageist' has been a recurrent topic for debate. The extra years resulting from a life-saving intervention would stack odds towards the young.

To say that age is only a disadvantage where the intervention is over£150,000 ignores the fact that moderately costly life-saving interventions with modest 'numbers needed to treat' can actually have high incremental cost-effectiveness ratios. This is made worse in older people, where few life years are gained.

For example, a£30,000 procedure that is life-saving for 20 per cent of recipients has a cost of£30,000 per life year gained in the 80-year-old Sir Michael describes.

The cost per QALY would be higher if those years are not of perfect health. Exactly the same circumstances for the three-year-old would result in a cost-per-life-year gain of hardly more than£2,000.

So age can matter, but attempts have been made to address this.

Discounting future health benefits, just as you would future costs, could help - though this is much-disputed territory.

But comparing interventions by their impact on health-related quality of life, not simply by gains in months or years, has great merit.

And the interventions Professor Bosanquet is worried about will get the boost they deserve in priority setting: a QALY league table that - for all its faults - can rank domiciliary podiatry above high-cost surgery must be worth consideration.

However I would agree with Professor Bosanquet that the QALY, or indeed any cost-utility analysis technique, is not good enough for exploring the value of some interventions - Alzheimer's treatment for example.

Conventionally, cost-utility analysis looks at the health gains and health costs. Cost-benefit analysis would be a more appropriate tool, looking at the whole package including impact on carers and so on.