DALYs and QALYs by samrat gurung

DALYs and QALYs

1. DALYs and QALYs Presented by: Samrat Gurung LA Grandee International College Pokhara, Nepal 1

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. 2

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. 3

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. 4

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. 5

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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 7

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 8

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 9

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. 10

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 11

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. 12

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. 13

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) 14

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 . 15

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 16

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)   17

18. THANK YOU!!! 18