Measuring the Burden of Disease

Interactive class tasks for epidemiology students focusing on calculating and interpreting YLL, YLD, DALY, and QALY metrics within a public health framework.
Epidemiology
Public Health
Daly
Qaly
Assignment
Author

Kostadin Kostadinov

Published

March 7, 2026

Practical Class Instructions:

This document contains four interactive scenarios designed for group work in epidemiology and public health workshops. Each group will analyze a specific case study to calculate burden of disease indicators, evaluate health-related quality of life, and debate the social and ethical implications of health resource allocation.

Reference Material

This assignment is based on the reading material: The Burden of Disease: Concepts, Measurement, and the Bulgarian Context. All calculations and interpretations must reference the definitions and metrics established in this text.

General Instructions for Students

Each group will independently solve a distinct burden of disease problem. Your task is to:

  1. Perform the Calculations: Calculate the requested metrics (YLL, YLD, DALY, QALY) using the provided data and formulas. Show your working.
  2. Evaluate the Public Health Impact: Interpret what the numbers mean for the affected community and the healthcare system.
  3. Participate in the “Battle” Presentation: Prepare a brief defense of your position on the assigned “Battle Point” for a class-wide debate.

Scenario 1: The Pediatric Outbreak (YLL & YLD Focus)

The Context: In the region of Equatoria, an outbreak of a vaccine-preventable paralytic disease occurs among children under age five. Local health officials need to present the “social cost” of this outbreak to justify an emergency mass-immunization budget.

The Data:

Parameter Value
Total Cases 600 children
Deaths 40 children (Avg. age: 2 years)
Survivors with Permanent Paralysis 560 children
Disability Duration 60 years
Disability Weight (DW) 0.25 (25% disabled)
Standard Life Expectancy at age 2 80 years

Your Task:

  1. Calculate YLL (Years of Life Lost): \(Deaths \times (Life Expectancy - Age at Death)\).
  2. Calculate YLD (Years Lived with Disability): \(Cases \times Duration \times Disability Weight\).
  3. Calculate Total DALYs (Disability-Adjusted Life Years): Sum of YLL and YLD.

Discussion Hints & “Battle” Points:

  • The Weight of the Young: Discuss why infectious diseases in children often generate significantly more DALYs than chronic diseases in the elderly. Consider the “life unlived” component.
  • Battle Point: One group argues that YLL (death) is the only “true” loss, while another argues that YLD (disability) is a heavier social burden because it requires lifelong healthcare and social support.
  • Guidance: Use the “Health Gap” concept to defend your position—how far does the reality fall from the ideal of full biological potential?

Scenario 2: The Chronic Heart Initiative (DALY & HRQL Focus)

The Context: A high-income nation is comparing two districts. District A has high rates of Ischemic Heart Disease (IHD), while District B has high rates of Depressive Disorders. The Ministry of Health can only fund one major screening program.

The Data:

District Primary Condition Mortality (Deaths/Year) Survival Context
District A Ischemic Heart Disease 500 Survivors have high HRQL scores (0.85 on SF-36)
District B Depressive Disorders 10 (Suicides) 2,000 people live with “Severe Depression” (DW = 0.65)

Your Task:

  1. Interpret the Burden: Based on the data, identify which district likely carries more YLLs and which carries more YLDs.
  2. Mortality vs. DALY: Explain why conditions like IHD, which often cause high mortality in older populations, might account for a higher percentage of total deaths than of total YLL.
  3. HRQL Assessment: Review the SF-36 concepts (vitality, social functioning, mental health). Describe how a patient with IHD might score differently across these domains compared to a patient with severe depression.

Discussion Hints & “Battle” Points:

  • The Mortality Bias: Discuss why traditional “death rates” would strongly favor funding District A, while DALY metrics might shift the focus toward the chronic suffering in District B.
  • Battle Point: Argue whether “Quality of Life” is too subjective to be used in national budget allocations.
  • Guidance: Should we rely solely on expert-derived disability weights (used in DALY) or on patient-reported outcomes (used in HRQL tools like SF-36)? Which is more “democratic”?

Scenario 3: Choosing the Treatment (QALY & Utility Focus)

The Context: A hospital board must decide between two treatments for a chronic condition. Treatment X is a surgery that provides an immediate return to full health but carries a 5% mortality risk. Treatment Y is a safe long-term medication that leaves the patient in a suboptimal health state.

The Data:

Treatment Expected Outcome Utility Elicitation (TTO Method) Cost
Treatment X 10 years of “Perfect Health” Utility (Q) = 1.0 $50,000
Treatment Y 12 years of “Suboptimal State” Indifferent between 12y with condition vs 6y perfect $20,000

Your Task:

  1. Calculate the Utility Value (Q): Use the Time Trade-Off results: \(Years_{Perfect} / Years_{Condition}\).
  2. Calculate QALYs (Quality-Adjusted Life Years): Multiply Expected Years of Life by the Utility Value (Q).
  3. Cost-Utility Analysis: Calculate the Average Cost-Effectiveness Ratio (ACER) per QALY for both treatments. (\(Cost / QALYs\)).

Discussion Hints & “Battle” Points:

  • Extra-Welfarism: Discuss the Extra-welfarist approach. How does this view differ from simply maximizing individual happiness?
  • Battle Point: One group defends Treatment X because it provides a higher number of QALYs on average. The other group attacks it on the grounds of Equity and Ethics, arguing that the 5% mortality risk is unacceptable even if the mathematical average is superior.
  • Guidance: If the patient dies during surgery, they get 0 QALYs. Is “Expected Value” a fair way to treat individual human lives?

Scenario 4: The Aging “Silver Tsunami” (HALE & Social Values Focus)

The Context: As life expectancy in a nation rises to 85 years, the government notices that HALE (Health-Adjusted Life Expectancy) is only 68 years. This indicates that citizens spend an average of 17 years in poor health.

The Data:

State Years in Disability Average Disability Weight YLL Component
Current State 17 years 0.30 0 (Lived to full expectancy)
Projected (After Policy) 10 years 0.30 0 (Lived to full expectancy)

Your Task:

  1. Calculate Current DALYs: For an individual over their lifespan (\(Years \times Weight\)).
  2. Calculate Projected DALYs: After a “healthy aging” program aims for the compression of morbidity.
  3. Define HALE: In plain language, explain the difference between standard life expectancy (85) and HALE (68) in this specific population.

Discussion Hints & “Battle” Points:

  • The Ethics of Age-Weighting: Discuss the GBD concept of age-weighting (valuing years lived by young adults more than those by the elderly).
  • Battle Point: One group argues that age-weighting is essential because young adults are “productive” and support children and the elderly. The other group argues this discriminates against the aged and violates social justice.
  • Guidance: Which “Social Value” should lead the nation’s health policy: Economic productivity or Universal Human Rights?

Evaluation Criteria:

  • Mathematical Accuracy (40%): Correct application of YLL, YLD, DALY, and QALY formulas.
  • Public Health Interpretation (30%): Clear explanation of the difference between mortality-only measures and burden-of-disease measures.
  • Critical Synthesis (20%): Depth of engagement with the “Battle Points” and ethical dilemmas.
  • Professional Communication (10%): Clarity of the group’s presentation during the class debate.