There is one important respect in which the committee’s model does not assign equal value to year of life no matter the age at which a person receives it. The model does not assume that population-averaged levels of health status are the same at all ages, since that assumption is clearly false. The model therefore does use population-based age-related adjustments for average health status of populations at different ages; for example, because the health status of the average 45-year-old is higher than that of the average 80-year-old, the model adjusts the value of life extension to reflect this difference and thereby assigns higher quality-adjustment value to a year of life at age 45 than at age 80. This does not give different value to a year of life at different ages simply because of the difference in age, but is only a way of adjusting for differences in average health status of populations at different ages. It also should not be confused with the age-weighting of the DALY which assigns different value to a year of life based simply on age itself and independent of the health-related quality of that life-year for the person who receives it.
There is a further respect in which adjustments for differences in the health-related quality of life of added life years is ethically controversial. Some vaccines are developed for a disease to which specific populations may be vulnerable because of predisposing conditions that also reduce their health-related quality of life. The vaccine will not affect the underlying health condition, nor its impact on the person’s quality of life. For example, people with untreated AIDS have a reduced health-related quality of life, as measured with the HUI, and are predisposed to other infectious diseases. Preventing those other infectious diseases by itself will not affect the quality of life decrement due to AIDS. On the other hand, the current influenza vaccine does not prevent all disease in elderly persons, but it does tend to avert life-threatening illness.
In each of these cases, the value of preventing death or illness, or alternatively of the years of life gained, will be reduced according to the effects that the preexisting condition or the resultant limitation have on the health-related quality of life of survivors. This means, to use the example of a vaccine to be given to prevent opportunistic infections in patients with AIDS (who have an already compromised quality of life), that a year of life extension for the patients with AIDS will have less value than a year of life extension produced by a different vaccine given to healthy persons or which leaves survivors with their initial healthy quality of life. In the context of disabilities, of which AIDS is an example covered by the Americans with Disabilities Act, it has been charged that this method of valuing health benefits discriminates against persons with disabilities