Global Burden of Disease Quiz 2019

QALY and DALY Measures

• QALY and DALY measure health states less than "excellent" health.
• DALY measures disability, while QALY measures quality of life.
• The perpendicular position of QALY and DALY on a graph can be seen in a later image.

QALY

• A chronic illness, such as schizophrenia, significantly impacting quality of life, will result in a disability score of 0.8.
• A score of 0 represents perfect health, and 1 represents death.
• A disability score of 0.8 also corresponds to a quality of life score of 0.2.
• One year of full health equals one QALY.
• Death means the QALY value drops to zero.
• QALY is used to calculate health-related quality across different life periods.

DALY

• DALY is calculated using years of life with disability (YLD) or years of life lost (YLL).
• YLL is based on gender and age-specific life expectancy, considering how many years life would continue with normal function if death did not occur.
• YLD is a product of disability severity and duration.

Case Study

• A 60-year-old experiences a heart attack.
• Without proper healthcare, the person would have died, but they survived.
• The person's health state corresponds to 0.9 on a scale of 0-1, representing 90% normal health.
• On a DALY chart, the equivalent value is 0.1.
• The person dies from a second heart attack at the age of 70.

Case Solution

• Years lost due to the first heart attack are calculated as follows: YLL (80-70) + YLD (10 * 0.1) = 11 DALY.
• The QALY from the medical intervention after the first heart attack is 10 years * 0.9 = 9 QALY.
• The sum of QALYs and DALYs equals the remaining time (60-80), which is 20 years.

QALY = DALY Reduction

• Comparing the cost of a medical intervention with its benefits yields comparable QALY gain and DALY reduction values.
• In the given example, the QALY gain is 9, and a DALY reduction of 11 was observed.

Scales

• QALY and DALY ranges are from 0 to 1.
• Calculating these criteria involves mathematical formulas.

Example: QALY Calculation

• A woman is expected to live 79 years.
• The first 40 years of her life had a QALY score of 0.95.
• Between ages 40 and 60, the QALY score was 0.90.
• Between ages 60 and 70, the score reduced to 0.80.
• Between ages 70 and 82, the QALY score is 0.70.
• The total QALY is calculated as: (40 x 0.95 + 20 x 0.9 + 10 x 0.8 + 12 x 0.7) = 72.4 QALY.
• Successful hip surgery at age 60 would've prevented a decline in QALY score until age 70, gaining an additional QALY (10 x (0.9 - 0.8)) = 1 QALY.

Calculation of QALYs as a Whole of the Country

• Generalizations in QALY calculations for an entire nation include:
  • Older person's QALY is equivalent to a younger person's QALY.
  • 0.50 QALY from one person and 0.25 QALY from two people are seen as equal.

For the QALY to be a Fit-for-Purpose Index

• The QALY index needs universally accepted definitions for health status and interventions.
• Assumptions in the Von Neumann-Morgenstern Expected Utilization Theory include a constant value for health status, regardless of duration, location, or other circumstances.
• Health status is also assumed to be equal for all individuals in the population contributing to QALY assessments.

DALY

• DALY was developed in the 1990s by WHO and WB to measure the negative impact of diseases and injuries on national health.
• More accurate health policies and decisions are expected based on these burdens.

DALY Calculation

• DALY is calculated using the International Classification of Impairments, Disabilities, and Handicaps.
• The index is not related to individual health but is indexed to illness, disability, and death.
• The Global Burden of Disease approach classifies data with 22 health-status-related indicators.

Burden of Disease Calculation

• Disease burden is calculated for all major diseases.
• Healthy life in younger ages is proportionally more valuable than in older ages.

DALY (Disability Adjusted Life Years)

• DALY is an absolute measure of health loss.
• It measures time lost due to premature death, diseases, or injuries, causing long-term functional impairments.
• A single DALY corresponds to the loss of one year of healthy life.

DALY Calculation Example

• Calculate DALY for a woman in a QALY assessment.
• Ideal life expectancy at birth is 82.5 years.
• Ideal life expectancy at age 60 is 84.83 years in the environment where the woman lives.

Assumptions for QALY Calculation

• The person lives in perfect health until age 60.
• Osteoarthritis occurs at age 60 with a disability score of 0.158 (untreated) or 0.108 (treated).
• Osteoarthritis's disability impact covers 24.83 years, with a calculated DALY loss of 3.9 (untreated) or 2.68 (treated).
• Diabetes may also be a factor contributing to loss in health, with a score between 0.012 and 0.078.
• Loss of 22.5 DALYs is calculated in case of death due to hip surgery at age 60.

Years of Life with Disability (YLD)

• YLD measures years lived with disabilities but does not lead to death.
• For example, a person who loses mobility from an accident and uses a wheelchair for 14 years has a YLD of 9.8 years.

Years of Life Lost (YLL)

• YLL represents years of life lost due to premature death.
• It is calculated by subtracting the person's age of death from the average life expectancy in that country.

DALY = YLL + YLD

• DALY is the sum of mortality and morbidity loads observed.
• Example: QALY calculated for a person is 80, morbidity is 9.8, and mortality is 6. The final QALY result is 80 - 15.8 = 64.2.

2019 Global Burden of Disease Survey

• The survey covers 286 causes of death, 369 diseases, and 87 risk factors.
• It evaluates the health profile of 204 countries nationally and globally.
• The survey was conducted by the University of Washington Institute for Health Metrics and Evaluation (IHME).

Disease Burden Studies

• Disease burden studies provide essential data for priority setting and evaluating health program effectiveness.
• The studies calculate the burden of diseases and injuries leading to premature death or long-term disability.
• The 2019 Burden of Disease Study provides detailed data at the level of gender, age, year, country, and region.

2019 Burden of Disease Survey

• The survey provides data on sex, age groups, years, countries, and regions.
• Disease and risk factors data are provided.
• Detailed comparisons for disease burdens are possible.

Other Measures

• Health-adjusted life expectancy (HALE) calculates health expectancy using a simple index equivalent to perfect health.
• Disability-adjusted life expectancy (DALE) is a variant of HALE focusing on years of healthy life lost due to disabilities.
• Disability-free life expectancy (DFLE) is a two-option criterion (0 for disability, 1 for no disability).

Active Life Expectancy (ALE)

• ALE is a bi-option, classifying individuals as active or inactive.

Healthy Year Equivalent (HYE)

• HYE uses QALY, but the evaluation criterion assesses perceived health (comfort and happiness) over time.

Test your knowledge on the Global Burden of Disease Survey conducted in 2019. This quiz covers essential concepts such as DALY, YLD, and health policy implications. Learn how health indicators are calculated and their significance in public health.