The Use of Death Certificate Data to Characterize Mortality Associated With Respiratory Syncytial Virus, Unspecified Bronchiolitis, and Influenza in the United States, 1999-2018

Abstract

Background: Death certificate data can improve our understanding of the mortality burden associated with respiratory syncytial virus (RSV) and influenza.

Methods: We used International Classification of Diseases, Tenth Revision codes listed on death certificates to characterize deaths from 1999 to 2018 as RSV, influenza, and unspecified bronchiolitis. We described the distribution of each cause of death by age, sex, race/ethnicity, place of death, and contributing causes of death.

Results: Over the 20-year study period, RSV, bronchiolitis, and influenza were listed as the underlying causes of death on 932, 1046, and 52 293 death certificates, respectively. Children <1 year of age accounted for 39% of RSV and bronchiolitis deaths, while 72% of influenza deaths were in adults ≥65 years. Children <1 year were more likely to die outside of the hospital from RSV, bronchiolitis, or influenza compared to all causes (P < .01), and black infants had the highest mortality rate for all 3 causes. Most infants dying from RSV did not have a high-risk condition listed on the death certificate. Death certificates captured 20%-60% of estimated excess RSV-attributable mortality in infants and <1% in seniors.

Conclusions: Thorough reporting on death certificates is an important public health goal, especially as new therapeutics become available. Infants had higher odds of dying out of hospital from respiratory pathogens compared to other causes, and race/ethnicity alone did not explain this disparity.

Keywords: RSV; bronchiolitis; death certificates; excess mortality; infant mortality; influenza.

Figure 1.

Place of death and race/ethnicity by age group for deaths attributed to underlying respiratory syncytial virus (RSV), bronchiolitis, influenza, and all causes. A, Distribution of deaths in each age group (<1, 1–4, 5–49, 50–64, ≥65 years) occurring in each location. Each bar represents 100% of deaths in the specified age group, and colors represent the percentage of deaths in each location, for each cause of death. B, Distribution of deaths in each age group in years by race/ethnicity. Each bar represents 100% of deaths in the specified age group. Colors indicate the percentage of deaths represented by each race/ethnicity.

Figure 2.

Age (0–11 months) at time of death in infants (<1 year of age) dying from underlying respiratory syncytial virus (RSV), bronchiolitis, or influenza. Bars represent the total number of deaths occurring during that month of age for each cause of death. Colored dots represent the number of deaths based on place of death (in-hospital or out-of-hospital).

Figure 3.

Comparison of number of respiratory syncytial virus (RSV) and influenza deaths based on death certificates and excess mortality estimates for each respiratory illness in children <1 year of age for 19 respiratory illness seasons (1999/2000 [99/00] through 2017/2018 [17/18]). Each bar represents the number of deaths for each season and cause of death (RSV, bronchiolitis, influenza) based on death certificate coding. The dots represent the range of deaths for each cause of death based on excess mortality estimates when using underlying pneumonia & influenza and underlying respiratory mortality as the dependent variables in regression analysis. Excess mortality estimates from: Hansen et al. Mortality associated with influenza and respiratory syncytial virus in the US, 1999–2018. JAMA Netw Open 2022; 5:e220527 (https://doi.org/10.1001/jamanetworkopen.2022.0527).