Comparative Methodologic and Practical Considerations for Life Expectancy as a Public Health Mortality Measure

Area of Science:

• Public Health
• Biostatistics
• Demography

Background:

• Life expectancy is a key public health metric for assessing mortality across populations.
• Commonly used length-of-life metrics include years of potential life lost before age 75 (YPLL-75) and premature age-adjusted mortality (PAAM).
• Methodological differences, data availability, and age-specific risks can influence metric selection.

Purpose of the Study:

• To calculate life expectancy at the US county level.
• To compare life expectancy calculations with YPLL-75 and PAAM.
• To explore associations between life expectancy and other health measures.

Main Methods:

• Utilized National Center for Health Statistics death data (2015-2017) and County Health Rankings & Roadmaps data (2019).
• Calculated county-level life expectancy using an abridged life table and the Chiang method.
• Employed studentized residuals to identify discordant metric values and correlations to test associations with health factors.

Main Results:

• Life expectancy varied widely across 3073 US counties (62.4 to 98.0 years; mean 77.4 years).
• Strong negative correlations were observed between life expectancy and YPLL-75 (r = -0.91) and PAAM (r = -0.95).
• Life expectancy associated with health factors like smoking, employment, and education; discordant values related to differing age structures.

Conclusions:

• Life expectancy calculations provide valuable insights into county-level mortality.
• The choice of length-of-life metric should consider methodological factors and audience communication needs.
• Understanding variations in life expectancy and its correlates is crucial for targeted public health interventions.