The value of DALY life: problems with ethics and validity of disability adjusted life years
BMJ 1999; 319 doi: https://doi.org/10.1136/bmj.319.7222.1423 (Published 27 November 1999) Cite this as: BMJ 1999;319:1423
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Sir,
Although the title of Arnesen's recent paper suggests that it is the
DALY concept that is critically reviewed, it appears that this concerns
only the operationalization of the valuation methods used to derive
disability weights.[1] The DALY belongs to a family of summary measures of
population health that combine information on mortality and non-fatal
health outcomes to represent a population's health.[2] [3] To take the varying
severity of disease sequelae into account, years lived with disability are
combined with a disability weight. Central in the concept is that we lose
important information when all years lived are considered equal regardless
of disability (the life expectancy approach) or that years lived with
disability are totally disregarded (as in healthy life expectancy
measures). We feel the DALY concept in the GBD has pulled the QALY
approach to a populations' health level, and that is progress.
We agree with Arnesen that the scientific development of the
derivation of disability weights is not yet completed. Their conclusion
that PTO1 and PTO2 should not necessarily result in the same values is
important: these are simply different questions. Much work in this field
is currently underway, both through the BIOMED project 'European
Disability Weights' and at WHO.
Arnesen, however, wrongly concludes that the values in DALYs
presuppose that life-years of disabled people are worth less than life-
years of people without disabilities. Disability weights in DALYs intend
to reflect differences in the relative severity in the burden of health
states. If one does not take this perspective into account, there can be
no benefit derived from any disease prevention or cure that reduces the
prevalence of disability. In resource allocation this would really
discriminate against those with a disability.
Finally, Arnesen and Nord report a survey conducted among 'the other
11 participants' of 'a workshop of European researchers working with
DALYs'. This workshop happened to be the first meeting of the BIOMED
project mentioned above, and it was held from 7 to 9 May, 1998, in
Rotterdam, The Netherlands. We, the authors of this letter and the co-
ordinating team of the BIOMED project, were present at this workshop. In
fact, there were 20 participants and an advisor. We were not included in
the survey and were not sent 'this summary of the valuation sessions', nor
'some questions'. Why not? Because Arnesen and Nord feared that our
answers would not fit in their interpretations? We feel the scientific
debate and development of the DALY concept and the disability weights is
important, but it deserves to be based on sound evidence.
Yours sincerely,
Marie-Louise Essink-Bot (a)
Marlies Stouthard (b)
Gouke Bonsel (b,c)
Louise Gunning-Schepers (b)
Paul van der Maas (a)
(a) Dept. of Public Health, Erasmus University Rotterdam, PO Box
1738, 3000 DR Rotterdam, The Netherlands. Tel. +31 10 408 7714. Fax +31 10
408 9455. E-mail of corresponding author: ESSINK@MGZ.FGG.EUR.NL
(b) Institute of Social Medicine and (c)Institute of Clinical Epidemiology
and Biostatistics, Academic Medical Centre / University of Amsterdam, PO
Box 22660, 1100 DD Amsterdam, The Netherlands.
References:
1. Arnesen T, Nord E. The value of DALY life: problems with ethics
and validity of disability adjusted life years. BMJ 1999;319:1423-25.
2. Murray CJL, Lopez AD. Mortality by cause for eight regions in the
world: the Global Burden of Disease study. Lancet 1997;349:1269-76. (+ 3
subsequent papers 1347-52; 1436-42; 1498-1504)
3. Murray CJL, Lopez AD. The Global Burden of Disease, vol. I.
Cambridge MA, USA: Harvard University Press, 1996.
Competing interests: No competing interests
Re: The problems with disability weights
Sir,
The reaction of Essink-Bot et al (1) to our article on ’The value of
DALY life’ (2) calls for some comments.
Whether DALYs at the end of the day will prove useful is an
interesting and controversial issue that our article did not address. In
our article we criticised the particular version of the person trade-off
technique (PTO1 and PTO2) that until recently formed the basis for
estimating disability weights in the Global Burden of Disease Project (3).
Our point was that the requirement of ’consistency’ between PTO1 and PTO2
de facto forces people to give answers to PTO1 that violate their ethical
beliefs and devalue the lives of the disabled. The underlying intentions
of the constructors of DALYs is a different issue. We of course prefer to
believe that the constructors think that the lives of disabled people
(for instance the blind) are as valuable as the lives of healthy people.
But then the following statement, made in defense against earlier
criticism, is somewhat unfortunate: ’Results are quite consistent across
groups that individuals prefer, after appropriate deliberation, to extend
the life of healthy individuals rather than those in a health state worse
than perfect health’ (4, p.726).
We conducted our mini-survey after the meeting in Rotterdam in May
1998 because we wished to report from inside ‘a black box’ of research and
wanted to make sure that other visiting participants shared our
impressions. Essink-Bot et al wonder why they were not included in the
survey. The answer is simple: They were the organisers (with the help of
Chris Murray) of the sessions that we experienced, with a view to train
the participants from other countries. It was of course out of the
question to ask those who were in charge to evaluate what it felt like to
be at the receiving end. Furthermore, when Trude Arnesen informed the
Dutch team that she was planning to do the survey as part of her PhD work,
she was asked not to do so (letter of 18 Sept 1998).
All visiting teams (Denmark, Sweden, England, France, Spain and
Norway) had problems with the Global Burden of Disease valuation approach
at the meeting in Rotterdam and took an interest in an alternative person
trade-off phrasing that was proposed at the meeting. The results of this
line of research remain to be seen. Eventually also Murray et al realised
that PTO1 (and PTO2 for that matter) was a mistake and proposed a new
approach (5).
References
1. Essink-Bot M-L et al. The problems with disability weights. BMJ
eletters;1999;319:1423.
2. Arnesen T, Nord E. The value of DALY life. BMJ 1999;319:1423-5.
3. Murray C, Lopez A. The Global Burden of Disease, vol 1. Cambridge:
Harvard University Press 1996.
4. Murray C, Acharya AK. Understanding DALYs. J Health Econ 1997;16:703-
30.
5. Murray C, Salomon JA, Mathers C. A critical examination of summary
measures of population health. GPE Discussion Paper No. 2, May 1999.
Geneva: WHO.
Competing interests: No competing interests