Temperature-mortality association during and before the COVID-19 pandemic in Italy: A nationwide time-stratified case-crossover study

Abstract

Objectives To identify the associations of temperature with non-COVID-19 mortality and all-cause mortality in the pandemic 2020 in comparison with the non-COVID-19 period in Italy. Methods The data on 3,189,790 all-cause deaths (including 3,134,137 non-COVID-19 deaths) and meteorological conditions in 107 Italian provinces between February 1st and November 30th in each year of 2015–2020 were collected. We employed a time-stratified case-crossover study design combined with the distributed lag non-linear model to investigate the relationships of temperature with all-cause and non-COVID-19 mortality in the pandemic and non-pandemic periods. Results Cold temperature exposure contributed higher risks for both all-cause and non-COVID-19 mortality in the pandemic period in 2020 than in 2015–2019. However, no different change was found for the impacts of heat. The relative risk (RR) of non-COVID-19 deaths and all-cause mortality at extremely cold (2 °C) in comparison with the estimated minimum mortality temperature (19 °C) in 2020 were 1.63 (95% CI: 1.55–1.72) and 1.45 (95%CI: 1.31–1.61) respectively, which were higher than all-cause mortality risk in 2015–2019 with RR of 1.19 (95%CI: 1.17–1.21). Conclusion Cold exposure indicated stronger impacts than high temperatures on all-cause and non-COVID-19 mortality in the pandemic year 2020 compared to its counterpart period in 2015–2019 in Italy.

Association of cause-specific hospital admissions with high and low temperatures in Thailand: a nationwide time series study

“…However, excluding data from 2020 to 2022 was necessary to prevent potential confounding effects induced by the coronavirus disease 2019 (COVID-19) pandemic. 48 During this period, governments implemented extensive containment measures, including quarantines, lockdowns, travel restrictions, and resource reallocation, to curb viral spread and reduce mortality. 49 These measures, both directly and indirectly, had a significant influence on temperature-related hospitalization rates.…”

“… 49 These measures, both directly and indirectly, had a significant influence on temperature-related hospitalization rates. 48 For example, stay-at-home orders would curtail outdoor physical activity, therefore decreasing exposure to non-optimum temperatures. 50 The COVID-19 pandemic also caused a shortage of healthcare resources, leading to increased vulnerability of patients to non-optimum temperatures.…”

“… 50 The COVID-19 pandemic also caused a shortage of healthcare resources, leading to increased vulnerability of patients to non-optimum temperatures. 48 , 51 Additionally, increased risk of mental illness during this period could have negatively impacted overall health outcomes. 52 …”

A new method to separate the impacts of interday and intraday temperature variability on mortality

“…Thus, it could be addressed if additional data are released, thereby facilitating the use of the new indices to assess the vulnerability of different subgroups. Third, the COVID-19 pandemic led to excess deaths during the study period, which may affect individual vulnerability to environmental factors such as temperature and air pollution [ 40 , 41 ]. However, the impacts would be similar for interday and intraday TV and thus the outbreak of COVID-19 is unlikely to have a great impact on our conclusion.…”