The mortality gap during the COVID-19 pandemic: an increase in excess deaths in the US relative to peer West European countries

By Bhavana KunkalikarReviewed by Danielle Ellis, B.Sc.Mar 31 2023

In a recent study published in the PLOS ONE journal, researchers assessed the impact of the coronavirus disease 2019 (COVID-19) pandemic on the mortality gap between individuals in the US and Europe.

Background

During the initial 20 years of the 21st century, there was a significant increase in the mortality gap between the US and other high-income countries. The COVID-19 pandemic may have exacerbated the existing disparity in COVID-19 mortality rates across different countries, as indicated by international comparisons.

By utilizing population-weighted average mortality rates from the five largest West European countries and applying them to the US population, it can be inferred that the mortality gap has resulted in a significant increase in the number of deaths in the US.

About the study

In the present study, researchers investigated the effect of the COVID-19 pandemic on the mortality gap between US and European residents.

The study calculated the excess fatalities resulting from various causes in the United States, utilizing data from the Short-Term Mortality Fluctuation (STMF) of the Human Mortality Database. The present dataset comprises mortality figures and mortality ratios for each week until the conclusion of 2021 in Wales and England, France, Italy, Germany, the US, and Spain, categorized by sex and five major age cohorts.

The study computed the population-weighted average age- and sex-specific mortality rates for the five European countries. This was achieved by adding the deaths as well as population exposure noted for each year, age group, and sex from each country. The resulting sum of deaths was then divided by the combined population exposure noted for each year, age group, and sex.

Counterfactual figures were computed by applying the mean European rates to the American population's exposure in the corresponding age and gender categories annually. The calculation of excess deaths involves determining the disparity between the observed number of deaths and the hypothetical number of deaths in a given year, categorized by age, sex, and other relevant factors.

To evaluate the precise impact of COVID-19 mortality and its temporal trends, counterfactual figures pertaining to the number of deaths in the United States attributed to COVID-19 were computed for the years 2020 and 2021, as well as for three intervening twelve-month intervals.

Results

Based on the average European rates, the projected figure for the total number of deaths in the United States in 2021 was 2,563,113. The recorded number of deaths in the United States for that year was 3,455,604. By subtracting this figure from the total number of deaths in 2021, it is revealed that there were 892,491 excess deaths.

When considering the sex and age cohorts in the United States, it was observed that population changes have only played a minor role in the rise of excess deaths between 2017 and 2021. The standardized measure of excess mortality had a 91.7% increase in 2021 compared to 2017. Furthermore, 2017 observed a rise in the overall number of mortalities by 18.7% due to excess mortality. In 2021, the US experienced a surge in deaths attributed to excess mortality, resulting in a 34.8% increase.

The majority of the rise in the standardized proportion of excess fatalities was reported from 2019 to 2021. It can be anticipated that variations in COVID-19-related fatality rates were accountable for the significant increase in the expanding mortality disparity between the United States and European populations.

A significant proportion of the upsurge in excess mortality rates between 2019 and 2021 can be ascribed to variances in COVID-19 mortality across different countries. The number of US deaths attributed to COVID-19 that can be classified as excess deaths, based on standardized metrics, rose to 223,266 in 2021 from 136,594 in 2020.

The incidence of excess deaths related to COVID-19 in the United States rose between 2020 and 2021, despite a slight reduction in the overall number of COVID-19-related deaths over a 12-month period. The marginal decrease was offset by a rise in the proportion of surplus fatalities ascribed to COVID-19. The fraction in question exhibited a degree of stability until mid-2021, after which it declined to 29.2% for the 12 months till 1 October 2021. However, it subsequently rebounded, rising to 48.2% in 2021.

In 2021, 31.0% of excess deaths were reported among males aged between 15 and 64. Additionally, 19.1% of excess deaths were also recorded among females within the same age bracket. In 2021, most excess fatalities were observed within that particular age bracket. In contrast, approximately 50% of fatalities occurring within the age range of 15 to 64 years were classified as excess deaths, indicating a greater proportion than other age cohorts. Consequently, the cumulative number of deaths in this demographic was elevated by 98.4% for females and 86.4% for males due to excess deaths.

Conclusion

The study findings highlighted the considerable increase in the proportion of excess fatalities in the US compared to the European population from 2000 to 2017. The standardized proportion of excess deaths observed between 2017 and 2021 can be attributed to over 50% of the variation in COVID-19 mortality rates. The observed dissimilarities could potentially be attributed to variations in the frequency of coexisting medical conditions correlated to COVID-19 case-mortality rates.