Cost_2 and Effect_2 are the cost and effect of the new (or more effective) intervention.Cost_1 and Effect_1 are the cost and effect of the comparator (e.g., standard care, no intervention).Expert Insight: A common misconception is to simply choose the intervention with the lowest total cost or highest total effect. CEA emphasizes the *incremental* ratio, as it guides decisions about moving from one option to a marginally better, but potentially more expensive, one.
Years of Life * Utility Value (0-1).Years of Life Lost (YLL) + Years Lived with Disability (YLD).Disease outbreak causes:
- 50 deaths (average age 40)
- 200 cases with disability weight 0.3 lasting 2 years
(Assume standard life expectancy at birth = 75 years for all)
Calculation of YLL:
Years of life lost per death = 75 (standard LE) - 40 (age at death) = 35 years
Total YLL = 50 deaths × 35 years/death = 1,750 years
Calculation of YLD:
Total YLD = 200 incident cases × 0.3 (disability weight) × 2 years (duration) = 120 years
Total DALYs = YLL + YLD
Total DALYs = 1,750 + 120 = 1,870 DALYs
Interpretation: This outbreak led to a substantial health burden, primarily driven by premature mortality.
Chronic Kidney Disease (CKD) in a region for a year:
- 10 deaths due to CKD (average age 65)
- 1,000 new cases of CKD (disability weight 0.2, average duration 10 years)
(Assume standard life expectancy at birth = 75 years for all)
Calculation of YLL:
Years of life lost per death = 75 (standard LE) - 65 (age at death) = 10 years
Total YLL = 10 deaths × 10 years/death = 100 years
Calculation of YLD:
Total YLD = 1,000 incident cases × 0.2 (disability weight) × 10 years (duration) = 2,000 years
Total DALYs = YLL + YLD
Total DALYs = 100 + 2,000 = 2,100 DALYs
Interpretation: For chronic diseases like CKD, the burden is predominantly from years lived with disability, emphasizing the importance of long-term care and management.
YLL = N × LL = 70 - 25 = 45 yearsTotal YLL Averted = 50 deaths × 45 years/death = 2,250 YLL averted per yearYLL calculation provides insight into the impact of an intervention on mortality, emphasizing how many years of productive life are gained back for the community. The choice of 'L' can significantly impact the result; using a standard global life expectancy allows for better cross-country comparisons, while local life expectancy offers a more regionally relevant perspective.
YLD = I × DW × LYLD (severe) = 300 × 0.4 × 0.5 = 60 YLD avertedYLD (uncomplicated) = 800 × 0.2 × 0.1 = 16 YLD avertedTotal YLD Averted = 60 + 16 = 76 YLD averted per yearDisability Weights are crucial; they reflect the severity of health states on a scale from 0 to 1. These weights are often derived from population surveys asking people to value different health states. For comprehensive and comparable analyses, researchers typically refer to standardized Global Burden of Disease (GBD) disability weights.
YLL Averted + YLD Averted2,250 + 76 = 2,326 DALYs averted per year"Every dollar or pound not spent cost-effectively represents a missed opportunity for improving health. It is, in essence, a life or a healthy year of life that could have been saved elsewhere if resources had been optimally allocated."Technical Insight: Efficiency-driven CEA often employs threshold analysis (e.g., WHO's 1-3x GDP per capita for a QALY) to define "cost-effective." These thresholds rarely incorporate explicit equity weights, potentially leading to decisions that disadvantage certain groups.
"The true measure of a society's moral character is not how it treats its average member, but how it treats its most vulnerable members. Justice in health demands that we actively prioritize those who are worst off, even if it means a less 'efficient' allocation of resources by narrow economic metrics."Ethical Framework Connection: This perspective often draws on John Rawls's "difference principle" (benefiting the least advantaged) or Norman Daniels's work on justice in health, emphasizing fair equality of opportunity.
Expert Insight: Dr. Anya Sharma, an economic development expert for South Asia, notes: "For development economics in South Asia, SA isn't just a technical step; it's a negotiating tool. It helps policymakers and donors find common ground on complex investments by showing how results hold under different perspectives on future value. It de-risks long-term commitments."
"Dynamic models are essential when interventions have an impact on transmission, disease progression rates, or population behavior. For infectious diseases or interventions targeting health determinants, ignoring these dynamics can lead to significantly biased CEA results." - Dr. Asha Devi, Health Economist, South Asian Health Institute