Qalys are good and Dalys are bad

Quality years? Yes, please.

Disability years? No thanks.

That’s the difference between these two adjusted life year metrics.

A Quality Year is simply a year lived in full health.

A Disability year is a year lived with disability.

The metrics for Qaly are straightforward: 100% is perfect health, 0% is, well, dead.

For Daly the metrics are similarly straightforward if you simply consider iy as a measure of how disabled you are. How disabled are you with a broken leg? Maybe 15%? (This is a good time to note that both Qaly and Daly are subjective measures, which gain power through comparisons and statistics.)

How disabled are if you’re dead? That wouldneed to be 100%. We can get into some interesting meta math and consider that torture ahould be ranked even higher than death, but death’s finality and irrwversability can serve as its trump card here and we’ll let it hang on to the coveted 100% spot.

Now, disability years, which include years of “additional” death, are added to provide the impact of an event, disease, war, etc. Even though death is really just 100% disabled, the concept of separating out the disability from death to create the Daly is reflected in this diagram:

Finally, the “adjusted” term in each acronym illustrates that the terms are characeristically used to show the effect of some variable. The variable effects, or “adjusts” Quality years or Disabled years by some percentage or amount.

Think you got it? Here’s a paper comparing the two that’s chock full of all the details you’ll need to evaluate:just how much did reading this post increase your quality of life?