Premature Death

Data Source

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. 

Premature Death is a rate

Rates measure the number of events (i.e., deaths, births) 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 3-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 can aid interpretation of variation in measures. If the error margins overlap year to year, it is 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, regardless of where the death occurred.

Some data are suppressed

A missing value is reported for counties with fewer than 20 deaths in the three year timeframe.

Measure limitations

YPLL can be difficult for public health practitioners to interpret and communicate to others. For example, the Florida Health Department’s Epidemiology Bureau found that county public health units often do not understand how to interpret YPLL.²

Deaths occurring after the age limit are not acknowledged in measures of premature death. Because of this, YPLL can fail to completely capture the burden of chronic disease, especially if the age cut-off is set too low.³

Numerator

The numerator is the cumulative number of years of potential life lost from deaths among county residents under age 75, over a three-year period.

Denominator

The denominator is 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.

Please note, the release of postcensal bridged-race population estimates ceased with the release of the Vintage 2020 estimates.

This measure can be used to track progress with some caveats. Premature death is a is a long-term health outcome, effects of interventions might not be reflected in this measure 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, meaning that small changes in small communities may be difficult to detect. It is important to note that the estimate provided in the County Health Rankings is a 3-average. In some cases, single-year YPLL estimates may provide a better measure of progress over time.

Disaggregation means breaking data down into smaller, meaningful subgroups. Disaggregated data are often broken down by characteristics of people or where they live. Disaggregated data can reveal inequalities that are otherwise hidden. These data can be disaggregated by:

• Age
• Gender
• Race
• Education

There is no national source of data on Years of Potential Life Lost (YPLL) that stratifies county data. However, premature mortality rates (the rate of death prior to age 75) are available on CDC WONDER, and can be calculated within counties by gender, age, race/ethnicity, and educational attainment.

You can also use the County Health Rankings’ Mortality and Life Expectancy Calculator if you have information on the population and deaths in the geography of interest to calculate Years of Potential Life Lost.

¹ Centers for Disease Control and Prevention. Premature mortality in the United States: Public health issues in the use of years of potential life lost. Morbidity and Mortality Weekly Report. 1986;35(suppl 2):1S-11S.

² McDonnell S, Vossberg K, Hopkins RS, Mittan B. Using YPLL in health planning. Public Health Reports. 1998;113:55-61.

³ 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; 5(7).