Flaws and uncertainties in pandemic global excess death calculations

Abstract

Several teams have been publishing global estimates of excess deaths during the COVID‐19 pandemic. Here, we examine potential flaws and underappreciated sources of uncertainty in global excess death calculations. Adjusting for changing population age structure is essential. Otherwise, excess deaths are markedly overestimated in countries with increasingly aging populations. Adjusting for changes in other high‐risk indicators, such as residence in long‐term facilities, may also make a difference. Death registration is highly incomplete in most countries; completeness corrections should allow for substantial uncertainty and consider that completeness may have changed during pandemic years. Excess death estimates have high sensitivity to modelling choice. Therefore different options should be considered and the full range of results should be shown for different choices of pre‐pandemic reference periods and imposed models. Any post‐modelling corrections in specific countries should be guided by pre‐specified rules. Modelling of all‐cause mortality (ACM) in countries that have ACM data and extrapolating these models to other countries is precarious; models may lack transportability. Existing global excess death estimates underestimate the overall uncertainty that is multiplicative across diverse sources of uncertainty. Informative excess death estimates require risk stratification, including age groups and ethnic/racial strata. Data to‐date suggest a death deficit among children during the pandemic and marked socioeconomic differences in deaths, widening inequalities. Finally, causal explanations require great caution in disentangling SARS‐CoV‐2 deaths, indirect pandemic effects and effects from measures taken. We conclude that excess deaths have many uncertainties, but globally deaths from SARS‐CoV‐2 may be the minority of calculated excess deaths.

Variability in excess deaths across countries with different vulnerability during 2020-2023

“…Extrapolations to countries with less reliable death and age structure data are precarious. 32 Socioeconomic factors are likely to have had a major impact on mortality during 2020-2023 also in other countries, perhaps even to a larger extent than in the 34 countries that we analyzed. [33][34][35] Their impact might have been even larger for non-COVID-19 deaths.…”

Analyses of academician cohorts generate biased pandemic excess death estimates

“…increased overdose deaths or deaths from poor access to care). 1,21,22 Also during the pandemic there were no excess deaths but consistently reduced mortality for children and adolescents. 17,23 Inappropriate extrapolation of the mortality experience from elderly frail populations to non-frail and younger populations was a major misunderstanding perpetuated in various forms throughout the pandemic.…”

“…Estimating pandemic excess death burden is difficult, even in countries with excellent death registration systems, because estimates depend on many assumptions. 1,2 In countries with deficient death registration, one option is to make inferences from cohorts where death data are hopefully complete. One approach is to use cohorts of members of prestigious academies, where birth and death dates are recorded for their members.…”

Excess mortality and years of life lost from 2020 to 2023 in France: a cohort study of the overall impact of the COVID-19 pandemic on mortality

“…Kowall et al explored six sources of variability that contribute to a wide range in reported excess mortality, and they suggested that future studies should objectively present differences in results according to methodological choices [5]. Ioannidis et al detailed nine sources of flaws and uncertainties, from the estimation to the interpretation of excess deaths [6]. In the end, Levitt et al [7] illustrated the implications of different methodological choices by detailing the differences between final estimates issued from four major contributions (the COVID-19 Excess Mortality Collaborators [8], Karlinsky and Kobak [9], The Economist team [10], WHO [11]): in France, estimates vary almost three-fold, from 57,767 to 155,000 excess deaths in 2020 and 2021.…”