County Health Rankings Model

COVID-19 Age-Adjusted Mortality*

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Use County Health Rankings’ model of health to explore the measures that influence how long and how well we live.

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About

All deaths occurring between January 1, 2020 and December 31, 2020 due to COVID-19, per 100,000 population (age-adjusted). The 2022 County Health Rankings used data from 2020 for this measure.

COVID-19 mortality data, alongside other leading causes of death in a county, provide context for the magnitude of pandemic impact on community health. Nationwide, COVID-19 was the underlying cause of 350,851 deaths in 2020, making it the third leading cause of death in the United States in 2020.[1] Deaths from COVID-19 have varied temporally, across geographies, and among racial and ethnic groups. COVID-19 deaths in 2020 reflect the early impacts of a dynamic pandemic. 

Studies using COVID-19 mortality data from 2020 have found relationships between socioeconomic disadvantage and increase in COVID-19 deaths. Examples include an increase in COVID-19 mortality rate in counties with higher historic daily fine particulate matter (PM 2.5) exposure.[2] Studies also found higher COVID-19 mortality in counties with a higher proportion of residents without health insurance.[3, 4] The disproportionate COVID-19 death rate among Black and Hispanic communities was well-documented in many county-level studies and highlights the serious problem of racial disparities in COVID-19 outcomes in the United States.[2-4] 

This measure is calculated using final death certificate data and is the most complete count of COVID-19 deaths in 2020 in the United States. Mortality data are less susceptible to underrepresentation compared to other measures of COVID impact such as case counts or hospitalization, which are subject to limitations in access to testing or care.   

Data and methods

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. 

Website to download data
For more detailed methodological information

Key Measure Methods

COVID-19 Age-Adjusted Mortality is a rate

COVID-19 Age-Adjusted Mortality measures the number of deaths among residents per 100,000 population. 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. 

COVID-19 Age-Adjusted Mortality 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. This measure is age-adjusted to the 2000 US population. 

What deaths count toward COVID-19 Age-Adjusted Mortality?

The National Center for Health Statistics (NCHS) classifies a death as a COVID-19 death if the death certificate is coded with the International Classification of Diseases, Tenth Revision (ICD-10) code U07.1. The code signifies that COVID-19 is listed as the underlying cause of death on the death certificate.[1, 5]   

Deaths are counted in the county where the individual lived regardless of where the death occurred.

Some data are suppressed

A missing values is reported for counties with fewer than 10 COVID-19 deaths in 2020.

Measure limitations

This measure cannot be directly compared with COVID-19 death data from sources outside NCHS. Other sources may only count laboratory-confirmed COVID-19 deaths and not “presumed” or “probable” COVID-19 deaths. Other sources may also attribute deaths to different locations (e.g., an individual’s county of residence versus the county where they died).  

This measure does not encapsulate all the population health impacts of the pandemic. Those experiencing emotional, mental, and physical health impacts resulting from the loss of loved ones or community members, and those who survived COVID-19 are not reflected in this measure. 

Numerator

The numerator is the number of deaths occurring between January 1, 2020 and December 31, 2020, due to COVID-19 in a county.

Denominator

The denominator is the total county population.

Can This Measure Be Used to Track Progress

The COVID-19 deaths have followed waves of transmission varying over time and geography. Caution and additional context should be applied when using COVID-19 age-adjusted mortality to measure progress.

Finding More Data

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

The US COVID Atlas https://theuscovidatlas.org/: Death counts from USA Facts, 1point3acres, and The New York Times. USA Facts death counts are taken from publicly available information from state and local agencies and may differ from death counts reported by the NCHS (see https://usafacts.org/articles/detailed-methodology-covid-19-data/). 

The CDC’s COVID Data Tracker https://covid.cdc.gov/covid-data-tracker/#datatracker-home: Death counts reflect what is reported to the CDC by states, territories, and other jurisdictions and not the NCHS death certificate data because this data takes longer to process. Therefore, the death counts on the CDC COVID-19 Data Tracker may be higher than the provisional and final counts from the NCHS[5]. The data in the COVID-19 age-adjusted deaths reflect final death counts from the NCHS for the year of 2020. 

Johns Hopkins University of Medicine Coronavirus Resource Center https://coronavirus.jhu.edu/: Data is compiled from state and county health departments and may differ from death counts reported by NCHS https://github.com/CSSEGISandData/COVID-19

COVID-19 Mortality Overview from the National Center for Health Statistics  https://www.cdc.gov/nchs/covid19/mortality-overview.htm: Provisional death counts for COVID-19 reported in real time (due to data lags, these provisional counts may not match other sources). Includes deaths attributed to COVID-19 on death certificates, place of death, death by age group, percentage of COVID-19 deaths by race and Hispanic origin, and other measures. 

References

[1] Murphy S.L., Kochanek K.D., Xu J.Q., and Arias E. 2021. Mortality in the United States, 2020. NCHS Data Brief, no 427. Hyattsville, MD: National Center for Health Statistics. https://stacks.cdc.gov/view/cdc/112079
[2] Wu, X., Nethery, R. C., Sabath, M. B., Braun, D., & Dominici, F. (2020). Air pollution and COVID-19 mortality in the United States: Strengths and limitations of an ecological regression analysis. Science advances, 6(45), eabd4049. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7673673/ 
[3] Millett, G. A., Jones, A. T., Benkeser, D., Baral, S., Mercer, L., Beyrer, C., Honermann, B., Lankiewicz, E., Mena, L., Crowley, J. S., Sherwood, J., and Sullivan, P. S. (2020). Assessing differential impacts of COVID-19 on black communities. Annals of Epidemiology, 47: 37-44. 
[4] Glance, L. , Thirukumaran, C. & Dick, A. (2021). The Unequal Burden of COVID-19 Deaths in Counties With High Proportions of Black and Hispanic Residents. Medical Care, 59(6): 470-476. https://oce.ovid.com/article/00005650-202106000-00002/PDF 
[5] “About CDC COVID-19 Data.” 2021. Centers for Disease Control and Prevention. https://www.cdc.gov/coronavirus/2019-ncov/covid-data/about-us-cases-deaths.html