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Years of potential life lost (YPLL) or potential years of life lost (PYLL), is an estimate of the average years a person would have lived if he or she had not died prematurely. It is, therefore, a measure of premature mortality. As an alternative to death rates, it is a method that gives more weight to deaths that occur among younger people. Another alternative is to consider the effects of both disability and premature death using disability adjusted life years. == Calculation == To calculate the years of potential life lost, the analyst has to set an upper reference age. The reference age should correspond roughly to the life expectancy of the population under study. In the developed world, this is commonly set at age 75, but it is essentially arbitrary. Thus, PYLL should be written with respect to the reference age used in the calculation: e.g., PYLL(). PYLL can be calculated using individual level data or using age grouped data.〔(【引用サイトリンク】 Calculating Potential Years of Life Lost (PYLL) )〕 Briefly, for the individual method, each person's PYLL is calculated by subtracting the person's age at death from the reference age. If a person is older than the reference age when he or she dies, that person's PYLL is set to zero (i.e., there are no "negative" PYLLs). In effect, only those who die before the reference age are included in the calculation. Some examples: # Reference age = 75; Age at death = 60; PYLL() = 75 - 60 = 15 # Reference age = 75; Age at death = 6 months; PYLL() = 75 - 0.5 = 74.5 # Reference age = 75; Age at death = 80; PYLL() = 0 (age at death greater than reference age) To calculate the PYLL for a particular population in a particular year, the analyst sums the individual PYLLs for all individuals in that population who died in that year. This can be done for all-cause mortality or for cause-specific mortality. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Years of potential life lost」の詳細全文を読む スポンサード リンク
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