DALYs (disability-adjusted life years) - the frequently used indicator for relative effects of public health interventions which specifically incorporate disability - need to be updated or replaced, says a Viewpoint in this week's edition of The Lancet.
Dr Daniel Mont, Disability and Development Team, The World Bank, Washington DC, USA, says that the notion of disability embodied in DALYs does not accord with that in the World Health Organisation's (WHO) International Classification of Functioning, Disability and Health (ICF).
He says: "Disability and health are difficult concepts to measure. In fact, the appropriate measure of disability depends on the reason behind its measurement."
He adds: "Critics claim that DALYs devalue the lives of disabled people. A year lived with a disability is counted as something less than a year lived without one. Conversely, saving the life of an individual with a disability does not improve the summary measure of health as much as saving the life of a person without a disability.
"The fear is that this fact will drive resources away from disabled people, making them even more vulnerable and disadvantaged than they already are in many societies."
With the ICF approach, the medical condition does not matter; however functional status does - in particular how the individual's functioning interacts with the environment to create disability.
The Viewpoint cites the example of a child born deaf, whose ability to function depends not only on its inability to hear but on the ability of its family and the community to use sign language.
Dr Mont says: "The effect on someone's life comes not from their functional status - in this case their mode of communication but from the extent to which that mode of functioning has been accommodated."
The Viewpoint goes on to discuss the problems that can stem from the views of some doctors that disability is a disorder to be cured rather than a functional status that needs to be accommodated.
Dr Mont says: "The main difficulty with DALYs is that they do not value interventions that enhance the lives of people with disabilities. To do so, they must draw on the social model of disability to look at how the environment interacts with functional status."
He concludes: "We should develop a limited set of measures aimed at addressing different aspects of health, which coincide within the approach taken by the ICF. Health - and indeed disability - are too complex to be encapsulated with one measure."