This document provides an overview of DALYs (Disability-Adjusted Life Years) and QALYs (Quality-Adjusted Life Years), which are measurements used to calculate the quality and quantity of life. DALYs measure overall disease burden in terms of years of life lost due to ill-health, disability or early death. QALYs measure effectiveness of treatments by combining quality and length of life. Both methods assign a weight between 0 and 1 to different health states, with 0 representing death and 1 representing perfect health. The document discusses the calculation and uses of DALYs and QALYs, and highlights some differences and criticisms of the approaches.

1. DALYs and QALYs
Presented by:
Samrat Gurung
LA Grandee International
College
Pokhara, Nepal
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2. INTRODUCTION
Quality adjusted life years(QALY) and Disability adjusted life
years(DALY) are both measurements to calculate the quality and
quantity of life either of individuals or the general population.
QALY was developed earlier than DALY. After 20 years, DALY was
developed by Harvard University in 1900. A decade later, it was
adopted by the World Health Organization (WHO).
The DALY is a measure of overall disease burden. The DALY is
becoming increasingly common in the field of public health and
health impact assessment.
And the QALY is considered to be the cornerstone of economic
analysis which combines both morbidity gains and the mortality
impact of a treatment.
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3. DALYs and QALYS are both measurements used in order to
calculate time (life years) of an individual or a general population.
The concept of time illness diseases and health treatments are
major and recurring factor in both methods of measurement.
They also share a common technique of weighing the cost per
healthy unit measure.
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4. DALYs
DALY stands for Disability-Adjusted Life Year.
DALY is the only quantitative indicator of burden of diseases
and measure of overall disease burden, expressed as the
number of years lost due to ill-health, disability or early death.
It reflects the total year lost(pre-mature mortality) or some
degree of disability(morbidity) during a period of time
DALYs are calculated by combining measures of life expectancy
as well as the adjusted quality of life during diseases or disability
for a population.
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5. Premature mortality is measured as a years of life lost (YLLs )
Morbidity is measured in terms of years lived with a disability
(YLDs)
One DALY represents one lost year of healthy life.
DALY is expressed in either 0 or 1, where
 0= perfect health
 1=death
 One DALY represents one lost year of healthy life.
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7. Uses
• Quantitative analysis of the burden of disease
• Analysis of cost-effectiveness of alternative interventions
• Selection of a package or list of interventions deliverable
within the available budget
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8. Calculation
• The calculation of DALYs of a woman who has been deaf since
she was 5 and dies when she is 50: ( Disability weight of
deafness is set at 0.33) :
• Number of healthy life years × the disability weight of full
health (0) + life years with disability (50) × disabilty weight
for deafness (0,33) + life years lost (30) × the weighting of
death (1)
• 5 × 0+ 45 × 0,33 + 30 × 1 = 47.35 DALYs
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9. QALYs
QALY are used to quantify the effectiveness of a new treatment
(eg. new medication) compared to current treatment for a particular
condition.
It can measure both the effectiveness and cost –effectiveness of an
intervention.
QALY gives an idea of how many extra months or years of life of a
reasonable quality a person might gain as a result of treatment
(particularly important when considering treatments for chronic
conditions)
It is expressed in either 0 or 1
 1=perfect health
 0=death
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10. QALY= Quality of life x length of life
• Health is defined as a function of two components:
1. length of life - i.e.. mortality
2. quality of life - i.e.. morbidity
• In health economic evaluations, the QALY is used to
quantify the effectiveness of a new medicine versus the
current one. In other words, the current standard of care is
taken as the baseline, and the QALYs gained from the new
(improved) intervention are counted in addition.
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11. 1. If an individual has perfect health for a period of 1 year, they
will be said to have 1 QALY.
i.e.. 1 Year of Life x 1 Utility Value = 1 QALY
2. If an individual lives in perfect health but only for half a year,
that individual will have 0.5 QALY.
i.e.. 0.5 Years of Life x 1 Utility Value = 0.5 QALY
3. If an individual lives for 1 year in a situation with 0.5 utility
(half of perfect health) that individual will have 0.5 QALY
i.e.. 1 Year of Life x 0.5 Utility Value = 0.5 QALY
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12. Uses of QALY-
• QALYs are used to quantify the effectiveness of a new treatment
(eg. new medication) compared to the current treatment for a
particular condition.
• QALYs can also be used to compare the health benefit of a new
treatment for one condition with the health benefit of a new
treatment for a different condition. .
• QALYs can also be used to evaluate the cost effectiveness of a
treatment, that is how much the drug or treatment costs per
QALY.
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13. • The above diagram demonstrates the QALYs that can be gained by an
individual from receiving treatment as opposed to no treatment.
• The area under the curve equates to the total QALY value. The lower
path shows the health profile if no treatment is received.
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14. Example
• If a person lives for 3 years with a disease and the current
standard of care for that disease means he/she lives with a
utility level of 0.7, that person will have 2.1 QALYs.
(3 Years of Life x 0.7 Utility Value = 2.1 QALYs)
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15. Relation between QALYs and DALYs
*DALYs = healthy years lost
*QALYs = healthy years gained
Here ‘red’ area denotes DALY and ‘white+red’ area
denotes standard life.
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16. Differences between QALY and DALY
QALY
• It measures quality and quantity
of care and life.
• Well developed earlier than DALY.
• It is an absolute measure used to
compare disease burden in
population.
• In QALY:
 1=perfect health
 0=death
• QALY= Quality of life x length of
life
DALY
• Measure health loss in the quality of
life.
• DALY was developed after 20 years.
• It is used to analyze clinical
intervention.
• In DALY:
 0= perfect health
 1=death
• DALY =YLL+YLD
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17. Critics of DALY & QALY
• Discriminates against young and the old (DALY)
• No Male-Female difference in length of life (DALY)
• Discounting future health outcomes (DALY)
• Doesn’t help determine the right intervention (DALY + QALY)
• Does not assess qualitative difference in outcomes (DALY + QALY)
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18. THANK YOU!!!
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