Difference between revisions of "Estimating disability-adjusted life years"

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'''Disability-adjusted life years''' (DALYs) are a method for combining different health impacts such as mortality and morbidity into a single common metric. The DALY is one of the most commonly used integrated health measures and was first introduced by Murray and Lopez (1996) in collaboration with World Health Organization and the Worldbank in an attempt to introduce morbidity in mortality-based health discussions. In effect, the DALY integrates many dimensions of public health impact e.g. the number of persons affected by a particular agent or event, the severity and duration of any health effects.<ref>Havelaar A., De Hollander A.E.M., Teunis P.F.M., Evers E.G., Van Kranen H.J., Versteegh J.F.M., Van Koten J.E.M., Slob W. Balancing the Risks and Benefits of Drinking Water Disinfection : Disabiliity Adjusted Life-Years on the Scale. Environ Health Perspect 108:315-321 (2000)</ref>
 
'''Disability-adjusted life years''' (DALYs) are a method for combining different health impacts such as mortality and morbidity into a single common metric. The DALY is one of the most commonly used integrated health measures and was first introduced by Murray and Lopez (1996) in collaboration with World Health Organization and the Worldbank in an attempt to introduce morbidity in mortality-based health discussions. In effect, the DALY integrates many dimensions of public health impact e.g. the number of persons affected by a particular agent or event, the severity and duration of any health effects.<ref>Havelaar A., De Hollander A.E.M., Teunis P.F.M., Evers E.G., Van Kranen H.J., Versteegh J.F.M., Van Koten J.E.M., Slob W. Balancing the Risks and Benefits of Drinking Water Disinfection : Disabiliity Adjusted Life-Years on the Scale. Environ Health Perspect 108:315-321 (2000)</ref>
  
This document describes briefly how Disability Adjusted Life Years (DALYs) can be used in a Health Impact Assessment (HIA). After a short introduction about integrated health measures, the calculation steps are described. Together with [[:media:DALY calculator.xls|Excel sheets]] made for this purpose (“DALY worksheets Intarese”), this information can be used as a basis for the calculation of environmental DALYs. [[DALY]].
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This document describes briefly how Disability Adjusted Life Years (DALYs) can be used in a Health Impact Assessment (HIA). After a short introduction about integrated health measures, the calculation steps are described. Together with [[:media:DALY calculator.xls|Excel sheets]] made for this purpose (“DALY worksheets Intarese”), this information can be used as a basis for the calculation of environmental DALYs.  
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The proponents of DALY's use the metric for atleast two separate exercise
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1. Positive exercise of measuring the burden of disease.
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2. The normative exercise for resource allocation.
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The burden of disease is simply measured as the sum of DALYs attributable to premature mortality and morbidity. for resource allocation, Murrey suggested that DALYs be used "in conjunction with the literature on cost effectiveness of health intervention" so as "using estimates of the burden of disease in determining health resource allocations". In using DALY for this purpose, the object is to minimize and aggregate DALYs subject to a given budget.
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Murrey states "{T}he he intended use of an indicator of the burden of disease is critical to its design. at least 4 objectives are very important
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* to aid in sitting health service (both curative and preventive) priorities.
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* to aid in sitting health research priorities.
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*         
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[[DALY]].
  
 
==Scope==
 
==Scope==

Revision as of 20:35, 15 February 2012



Disability-adjusted life years (DALYs) are a method for combining different health impacts such as mortality and morbidity into a single common metric. The DALY is one of the most commonly used integrated health measures and was first introduced by Murray and Lopez (1996) in collaboration with World Health Organization and the Worldbank in an attempt to introduce morbidity in mortality-based health discussions. In effect, the DALY integrates many dimensions of public health impact e.g. the number of persons affected by a particular agent or event, the severity and duration of any health effects.[1]

This document describes briefly how Disability Adjusted Life Years (DALYs) can be used in a Health Impact Assessment (HIA). After a short introduction about integrated health measures, the calculation steps are described. Together with Excel sheets made for this purpose (“DALY worksheets Intarese”), this information can be used as a basis for the calculation of environmental DALYs.

The proponents of DALY's use the metric for atleast two separate exercise

1. Positive exercise of measuring the burden of disease.

2. The normative exercise for resource allocation.

The burden of disease is simply measured as the sum of DALYs attributable to premature mortality and morbidity. for resource allocation, Murrey suggested that DALYs be used "in conjunction with the literature on cost effectiveness of health intervention" so as "using estimates of the burden of disease in determining health resource allocations". In using DALY for this purpose, the object is to minimize and aggregate DALYs subject to a given budget.

Murrey states "{T}he he intended use of an indicator of the burden of disease is critical to its design. at least 4 objectives are very important

  • to aid in sitting health service (both curative and preventive) priorities.
  • to aid in sitting health research priorities.

DALY.

Scope

How should DALYs be calculated so that it is in accordance with the WHO?

Definition

[2]

Result

DALY in case of recovery:

Peffect  * (Prec* YLDrec * Sev)


DALY in case of death

Peffect * [Pdie *(YLDdie * Sev) + L.E. - C.A. - YLDdie]


DALY if 'diseased' to natural life expectancy (chronic disease)

Peffect * (1 - Prec - Pdie) * (L.E. - C.A.) * Sev


Where:

  • Peffect = Probability of the considered effect (dose-response relationship)
  • Prec = Probability to recover from a disease
  • Pdie = Probability to die from a disease
  • YLDrec = Years Lived with Disability in case of full recovery [3]
  • YLDdie = Years Lived with Disability in case of death
  • Sev = Severity of the effect (0-1)[2] [4] [5]
  • L.E. = Life expectancy
  • C.A. = Current Age

References

  1. Havelaar A., De Hollander A.E.M., Teunis P.F.M., Evers E.G., Van Kranen H.J., Versteegh J.F.M., Van Koten J.E.M., Slob W. Balancing the Risks and Benefits of Drinking Water Disinfection : Disabiliity Adjusted Life-Years on the Scale. Environ Health Perspect 108:315-321 (2000)
  2. 2.0 2.1 Murray CJL, Lopez AD, eds. 1996. The global burden of disease: a comprehensive assessment of mortality and disability from diseases, injuries and risk factors in 1990 and projected to 2020. Cambridge, Harvard School of Public Health on behalf of the World Health Organization and the World Bank.
  3. Data by regions (European), for example YLD (years of life lived with the disease)
  4. An update of the disability weights
  5. Dutch disability weights Available only in Dutch.