Table 2.
Variables and formula for Disability Adjusted Life Years (DALYs) and basic formulation for Quality-Adjusted Life Years (QALYs).
| Description | Unit | Symbol |
|---|---|---|
| Years of life lost due to death before expectation of life had the disease not occurred | years | YLL |
| Years lost due to disability multiplied by disability weight | years | YLD |
| Number of deaths | number | N |
| Number of incident cases | number | I |
| Life expectation or duration of disability | years | DW |
| Discount rate | % | r |
| Age-weighting correction constant | 0.1658 | C |
| Parameter for age-weighting function | 0.04 | b |
| Age at onset of disease | years | a |
| Parameter for setting age-weighting | 1 or 0 | K |
|
DALY = YLL + YLD where YLL = N Ce(ra) / ( +r)2 [e (+r)(L+a) [-( +r) (L+a)-1] - e (+r)a [–( r)a-1]] YLD = I DW { K Ce(ra) / ( +r)2 [e (+r)(L+a) [-( + r)(L+a)-1] - e (+r)a [–( r)a-1]] + (1-K) (L/r) (1– e rL )} QALYs (basic formulation) QALY = Life years lived (duration) x quality of life (health state) indicator° | ||