DALY (Disability Adjusted Life Years)

1. Description

DALY (Disability Adjusted Life Years) is an index quantifying number of years lost from treatment compared to the national life expectancy.[1] It weighs the individual level of disability and counts both the year of loss due to disability and the year short of the local/national life expectancy. DALY can also act as a population measure by summing up DALYs for each individual in the population.

2. Evaluation

2.1 Principle
  • DALYs provide a common currency for both benefit and risk (in terms of life lived and lost) adjusted for "disability".
  • DALYs are meant to complement QALYs.
  • DALYs can be combined with QALYs using the benefit-risk ratio (BRR) approach to estimate benefit-risk balance.
  • The principles are however flawed, without a fixed reference population.

2.2 Features
  • Benefit and risk are integrated, and so is the time dimension.
  • DALY accommodates multiple criteria.
  • A sensitivity analysis can be performed on various parameters in DALYs e.g. different reference population or data.

2.3 Visualisation
  • Visualisations similar to the one used for QALYs may be used.

2.4 Assessability and accessibility
  • The use of the local/national life expectancy to determine the years of life lost is problematic.
  • DALY is otherwise only semantically different from QALY if the reference population issue is solved.

3. References

[1] Airoldi M, Morton A. Adjusting Life for Quality or Disability: Stylistic Difference or Substantial Dispute? Health Econ. 2009 18:1237-1247.