Years of Potential Life Lost (YPLL) is a widely used measure of the rate and distribution of premature mortality. Measuring premature mortality, rather than overall mortality, reflects the County Health Rankings’ intent to focus attention on deaths that could have been prevented. YPLL emphasizes deaths of younger persons, whereas statistics that include all mortality are dominated by deaths of the elderly. For example, using YPLL-75, a death at age 55 counts twice as much as a death at age 65, and a death at age 35 counts eight times as much as a death at age 70.
Premature Death is a Rate
Rates measure the number of events (i.e., deaths, births, etc.) in a given time period (generally one or more years) divided by the average number of people at risk during that period. Rates help us compare data across counties with different population sizes. All the years of potential life lost in a county during a three-year period are summed and divided by the total population of the county during that same time period. This value is then multiplied by 100,000 to calculate the years of potential life lost under age 75 per 100,000 people.
Premature Death is Age-Adjusted
Age is a non-modifiable risk factor, and as age increases, poor health outcomes are more likely. We report an age-adjusted rate in order to fairly compare counties with differing age structures. YPLL is age-adjusted to the 2000 US population.
Premature Death is a Rare Event (statistically speaking)
Premature death is a relatively rare event in most counties. Counties with smaller populations can see a lot of change in their rates of premature death data from year to year. Such changes are usually due to normal variation and are not necessarily caused by any actual change in the underlying risk of premature death in the county. To help determine if the premature death change in a county is due to normal variation or real change, we recommend examining the provided error margins. Error margins are statistical tools that take into account variation in measures. If the error margins overlap year to year, it’s less likely that the variation in premature death reflects real underlying changes.
What Deaths Count Toward Premature Death?
Deaths are counted in the county where the individual lived, not the county where they died.
Some Data Are Suppressed
A missing value is reported for counties with fewer than 20 deaths in the three-year time frame.
YPLL can be difficult for lay people and public health practitioners to interpret. For example, the Florida Health Department’s Epidemiology Bureau investigated this issue and learned that county public health units often do not understand how to interpret YPLL. Further, deaths that occur after the age limit are not accounted for at all. Because of this, YPLL can fail to completely capture the burden of chronic disease, especially if the age cut-off is set too low.
The number of years of potential life lost for deaths that occurred amongst people who reside in a county under age 75 over 3 years.
The aggregate population under age 75 for the three years from the bridged-race postcensal estimates of the July 1 resident population released by the National Center for Health Statistics.
This measure can be used to track progress with some caveats. Premature death is a very long-term health outcome, effects on which might not be seen for years or even decades after a program or policy is implemented. Premature death is also a relatively rare event, especially in small counties. Statistics depend on large numbers of events to detect small changes, and small changes in small communities may be hard to detect. It is important to note that the estimate provided in the County Health Rankings is a 3-year average. In most cases, it would be better to calculate single-year YPLL estimates to measure progress over time.
Years of Data Used
National Center for Health Statistics - Mortality Files
Data on deaths and births were provided by NCHS and drawn from the National Vital Statistics System (NVSS). These data are submitted to the NVSS by the vital registration systems operated in the jurisdictions legally responsible for registering vital events (i.e., births, deaths, marriages, divorces, and fetal deaths). In prior years of the Rankings, Premature Death was calculated by the National Center for Health Statistics, but this year the Mortality-All County (micro-data) file was requested. This allowed us to calculate Premature Death and Life Expectancy ourselves. While most calculations of mortality rates can be downloaded from CDC WONDER, the calculation of Years of Potential Life Lost and Life Expectancy requires raw data files.
 Centers for Disease Control and Prevention. Premature mortality in the United States: Public health issues in the use of years of potential life lost. MMWR Morb Mortal Wkly Rep. 1986;35(suppl 2):1S-11S.
 McDonnell S, Vossberg K, Hopkins RS, Mittan B. Using YPLL in health planning. Public Health Rep.1998;113:55-61.
 Dranger E, Remington P. YPLL: A Summary Measure of Premature Mortality Used in Measuring the Health of Communities. Madison, WI: University of Wisconsin Population Health Institute; 2004. Issue Brief 5(7).