Questions: Global Burden of Disease and Health Metrics

Question 1

A country reports 50,000 deaths per year from depression but zero years lived with disability (YLD) attributed to depression. Which of the following best explains why this country's DALY count for depression is likely still substantial?

• A. DALYs only count deaths, so zero YLD means zero DALYs
• B. Depression causes very few years of life lost, so YLL dominates
• C. Depression is primarily a morbidity condition — most burden comes from YLD, not YLL — so a country that only counts deaths will dramatically undercount DALYs
• D. GBD does not include mental health conditions in DALY calculations

Answer: (C)

DALYs = YLL + YLD. Depression causes very few direct deaths but imposes enormous morbidity — years of reduced function, disability, and quality-of-life loss. A country that counts deaths but not disability will capture YLL but miss most of the burden. This is precisely the insight that makes DALYs more informative than mortality counts alone.

Question 2

Disability weights used in DALY calculations are objective, biologically determined values that do not involve value judgments.

• T. True
• F. False

Answer: False

Disability weights are derived from population surveys asking respondents to compare health states and rate their severity. They reflect societal values and preferences, not biological facts. Different survey methodologies and populations produce different weights, and the choice of whose values to use is inherently normative. This is one reason DALYs should be interpreted as structured estimates, not objective measurements.

Question 3

Why might a country's top 10 causes of death look very different from its top 10 causes of DALYs?

Model answer: Some conditions (like lower back pain, depression, or hearing loss) cause substantial disability and years lived with reduced function but rarely kill people directly, so they rank high in DALYs (via YLD) but low in mortality statistics. Conversely, conditions like stroke may kill quickly, contributing heavily to YLL. Deaths alone miss the burden of non-fatal but disabling conditions.

This divergence is the central motivation for the DALY metric. Mental health conditions, musculoskeletal disorders, and sensory impairments collectively account for a large share of global DALYs but appear underrepresented in death statistics. Policy makers who allocate resources only based on mortality data systematically underfund conditions that reduce quality of life without killing quickly.