Relationship between COVID-19 cases and monthly mortality from all causes, cancer, cardiovascular diseases and diabetes in 16 countries, 2020-21

Background: During the COVID-19 pandemic, mortality from some chronic diseases increased. In this study, we evaluated monthly excess mortality from all causes, cancer, cardiovascular diseases (CVD) and diabetes during the months of 2020 and 2021, examining its relationship with COVID-19 cases. Methods: Monthly cause-specific mortality data were downloaded from public repositories of national statistics offices or directly requested from them, and population data were obtained from the United Nations archives. Excess deaths were estimated as the difference between observed and expected deaths. Monthly expected deaths for 2020 and 2021 were calculated using a quasi-Poisson regression model trained on 2010-19 data (or a shorter timespan if the full decade of data was not available). To quantify the correlation between COVID-19 cases and monthly excess mortality, we used the Spearman's correlation coefficient (rs). Results: The study included 16 countries that provided monthly national data on causes of death (Argentina, Austria, Brazil, Switzerland, Chile, the Czech Republic, Germany, Georgia, Hungary, Italy, Lithuania, Latvia, Mexico, Serbia, Slovakia and the USA). A positive correlation was found between COVID-19 cases and monthly excess mortality from all causes in all countries (rs ranging from 0.61 to 0.91), from CVD in 11 countries (rs ranging from 0.45 to 0.85) and for diabetes in 13 countries (rs ranging from 0.42 to 0.79). Excess mortality above 5% was estimated from all causes in 14 countries for both 2020 and 2021, from CVD in seven countries for 2020 and in nine countries for 2021, and from diabetes in 11 countries for 2020 and in 12 countries for 2021. No excess above 5% was estimated for cancer mortality in any of the countries considered. Conclusions: Excess mortality from CVD and diabetes persisted in several countries throughout 2021. These increases coincide with COVID-19 peaks, supporting a short-term impact of the COVID-19 pandemic on mortality from these causes.