Does average years of life loss (AYLL) can be used to monitor the progress of a particular disease over time? If so, does it require to be age-adjusted? What does an increasing AYLL over time suggest?
If the AYLL increases over time, then at least two possibilities - 1. Higher prevalence/incidence of that disease adds up to more YLLs, 2. Better treatment means people are no longer dying of the disease, but live longer with it e.g. HIV, some cancers etc
Metrics like YLLs, years lived with disability etc are great for assessing the burden of a particular disease, but like all data, it's vital to know what the numbers mean, what the caveats are, and what conclusions you can realistically draw from the data.
Age-adjusted? I would suggest it depends what you're doing. You might be comparing global burden of HIV across all ages, you might be wanting to know what the YLLs are for HIV compared to pneumonia (in which case, under 5s bear the highest pneumonia burden, not so for HIV where the burdens are seen at an older age).
As AYLL is calculated by adding YLL and divided by number of deaths, an increasing trends over iltime of AYLL indicates people are dying at earlier age. Obviously YLL is measured by subtracting age at deaths from life expectancy. So your first paragraph somewhat contradictory. Am I wrong?
Yes, if one is interested in changes in life expectancy over time. You then need to estimate an average of YLL per specified period, say, 5-year periods, get at least 3 period points, to measure trend. hope this helps
For trends analysis purpose, it is recommended to use the age-standardize YLL rate instead of YLL rate. This is important because the age structure of the population changes over time, so it requires to adjust for age as a confounder factor.
I hope this helps.
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