|Potential Years of Life Lost (PYLL)
(sometimes, Years of Potential Life Lost, or YPLL)
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1. Core Knowledge:
Deaths occurring early in life are considered a more serious loss than later deaths, so in comparing the impact of diseases it may be better to consider not only total numbers of deaths, but also the age at which they occur. People who die prematurely are said to have lost years of potential life. 'Premature' can be defined in terms of the average life expectancy for a person of that sex, or an arbitrary value (such as 75 years) can be used for everyone. Hence, a person who dies from a myocardial infarction at age 55 would have lost 20 years of potential life.
These values could be summed over a population to indicate the impact (in terms of potential years of life lost) due to a particular disease in the population; this can be used in setting priorities among health issues in a society. Here, deaths that occur at younger ages (doing wheelies on your 1100 cc. Kawasaki) receive more weight than deaths that occur late in life (my pneumonia). This reflects a social judgment that the death of a young person is more significant than the death of an older person. [Discussion point: is this the best way? Are there disadvantages? See the US NCHS link below]
The chart below show PYLL data for Canada for 2007. Neoplasms lead, but for men, injuries cause an equal burden of premature mortality.
3. Additional Information:
Link to Public Health Agency of Canada, which has an excellent web resource on Chronic Disease Surveillance. This allows you to print off maps showing the distribution of all kinds of disease - go play with it!
There is a U.S. web site from the US National Center for Health Statistics that lets you play with PYLL data (click on the 'Related Links' button).
Link to related concepts: Disability-adjusted life years (DALYs)
Population Attributable Risk
Updated January 13, 2015