MEANING OF YEARS OF LIFE LOST
years of life lost (YLL, years of potential life lost, YPLL, potential years of life lost, PYLL) a measure of premature mortality that calculates the number of additional years a person could have expected to live, on average, had they not died prematurely. A reference age intended to represent the total number of years a person can expect to live, on average, is required for the calculation: this is often given in square brackets after YLL (typically YLL ). Negative values for YLL are not used: if somebody survives longer than the reference age, their YLL is calculated as 0. YLLs for different diseases can be compared across populations to give an indication of which diseases carry the greatest burden of premature mortality.