• policy
• genetic therapy
• ethics

It is hard to argue with the proposition that value for money should guide health spending. However, even after decades of development, economic evaluation is still a work in progress. As applied, it deals poorly with issues of social justice, ageing and end of life issues; cases involving small numbers—such as decisions about orphan drugs—are also contested.

Unfortunately, differences in incremental cost-effectiveness ratios are presented with a degree of precision which contributes to an ‘illusion of validity’.1 Nobel Laureate Amartya Sen has suggested that ‘when all the requirements of ubiquitous market-centred evaluation have been incorporated into the procedures of cost–benefit analysis, it is not so much a discipline as a daydream’.2

As with any approach to public decision making, the use of economic evaluation rests on an implicit social licence, including that the decision making is fair and reasonable. Many countries have developed special policies for rare, ‘ultrarare’ or ‘orphan’ diseases to moderate the effect of a ubiquitous application of economic evaluation. The threshold for defining ‘small’ or rare is a matter of judgement and ranges between 2 and 80 per 100 000 population.3

Magalhaes challenges the ethical basis of special programmes for low incidence conditions and argues against such provisions. In this commentary, I will argue the contrary: that there are good reasons …