key: cord-0857158-0i28vstv authors: Yu, W.; Xu, R.; Ye, T.; Han, C.; Li, S.; Guo, Y. title: COVID-19 pandemic increased the magnitude of mortality risks associated with cold temperature in Italy: A nationwide time-stratified case-crossover study date: 2020-09-18 journal: nan DOI: 10.1101/2020.09.15.20194944 sha: a66f6ca4f92a8badd82169380c04904c656dc5fa doc_id: 857158 cord_uid: 0i28vstv Abstract Backgrounds: The coronavirus disease 2019 (COVID-19) pandemic and some containment measures have changed many people lives and behaviours. Whether the pandemic could change the association between cold temperature and mortality remains unknown. Objectives: We aimed to assess whether the association between cold temperature and all-cause mortality in the pandemic period has changed compared to non-COVID-19 period (2015-2019) in Italy. Methods: We collected daily all-cause mortality data and meteorological data for 107 Italian provinces from 1, January 2015 to 31, May 2020. A time-stratified case-crossover design with the distributed lag non-linear model was used to examine the association between cold temperature and all-cause mortality during the first three months (from March to May in 2020) of the COVID-19 outbreak and the same months in 2015-2019. Results: The relative risk (RR) of all-cause mortality at extreme cold temperature (2.5th percentile of temperature at 3 {degrees}C) in comparison with the minimum mortality temperature (24 {degrees}C) was 4.75 [95% confidence interval (CI): 3.90-5.79] in the pandemic period, which is more than triple higher than RR [1.41 (95%CI: 1.33-1.50)] in the same months during 2015-2019. The shift in cold-mortality association was particularly significant for people aged 65-74 years [RR (95%CI): 5.98 (3.78-9.46) in 2020 versus 1.29 (1.10-1.51) in 2015-2019], 75-84 years [5.25 (3.79-7.26) versus 1.40 (1.25-1.56)], and [≥] 85 years [5.03 (3.90-6.51) versus 1.52 (1.39-1.66)], but not significant for those aged 0-64 years [1.95 (1.17-3.24) versus 1.24 (1.05-1.48)]. Conclusion: The findings suggest that the COVID-19 pandemic enhanced the risk of cold temperature on mortality in Italy, particularly among the elderly people. Further studies are warranted to understand the exact mechanism when detailed data are available. With the coronavirus disease 2019 (COVID-19) infection sweeping across the globe at 52 a startling speed (Bedford et al. 2020) , restrictive social containment measures such as 53 social distance, travel restriction, and regional emergency lockdown, have been widely is the author/funder, who has granted medRxiv a license to display the preprint in (which was not certified by peer review) preprint The copyright holder for this this version posted September 18, 2020. . https://doi.org/10.1101/2020. 09.15.20194944 doi: medRxiv preprint The association between ambient temperature and mortality/morbidity outcomes has 76 been well-documented (Gasparrini et is the author/funder, who has granted medRxiv a license to display the preprint in (which was not certified by peer review) preprint The copyright holder for this this version posted September 18, 2020. In this study, we aimed to identify the risk of all-cause mortality associated with is the author/funder, who has granted medRxiv a license to display the preprint in (which was not certified by peer review) preprint The copyright holder for this this version posted September 18, 2020. We collected the hourly ambient temperature (at 2 meters above the land surface) and 129 ambient dew point temperature at 0.1°×0.1° spatial resolution from the ERA5 dataset 130 (ERA5) (https://cds.climate.copernicus.eu/cdsapp#!/home). We aggregated all hourly 131 observations into daily data. This dataset has good temporal and spatial coverage in 132 Italy, but it might be less accurate than observations from weather stations. Thus, we 133 calibrated the ERA5 daily mean temperature and ERA5 daily mean dew point is the author/funder, who has granted medRxiv a license to display the preprint in (which was not certified by peer review) preprint The copyright holder for this this version posted September 18, 2020. is the author/funder, who has granted medRxiv a license to display the preprint in (which was not certified by peer review) preprint The copyright holder for this this version posted September 18, 2020. is the author/funder, who has granted medRxiv a license to display the preprint in (which was not certified by peer review) preprint The copyright holder for this this version posted September 18, 2020. is the author/funder, who has granted medRxiv a license to display the preprint in (which was not certified by peer review) preprint The copyright holder for this this version posted September 18, 2020. is the author/funder, who has granted medRxiv a license to display the preprint in (which was not certified by peer review) preprint The copyright holder for this this version posted September 18, 2020. is the author/funder, who has granted medRxiv a license to display the preprint in (which was not certified by peer review) preprint The copyright holder for this this version posted September 18, 2020. (Table S1 ). We replaced the study period of 2015-2019 with every single year from 250 2015 to 2019 to examine the stability of the association between temperature and all-251 cause mortality in the period with no pandemic, which gave similar results (Fig. S3) . 252 Additionally, we changed the maximum lags days to 18 and 24 days in our model, and 253 it did not modify the results (Fig. S4) . Consequently, we believe that our models 254 adequately captured the main effects of temperature on mortality. To the best of our knowledge, our study is the first to investigate the cold-related excess is the author/funder, who has granted medRxiv a license to display the preprint in (which was not certified by peer review) preprint The copyright holder for this this version posted September 18, 2020. is the author/funder, who has granted medRxiv a license to display the preprint in (which was not certified by peer review) preprint The copyright holder for this this version posted September 18, 2020. is the author/funder, who has granted medRxiv a license to display the preprint in (which was not certified by peer review) preprint The copyright holder for this this version posted September 18, 2020. is the author/funder, who has granted medRxiv a license to display the preprint in (which was not certified by peer review) preprint The copyright holder for this this version posted September 18, 2020. We also investigated the discrepancy effects by sex and age groups in the pandemic. The difference in temperature-related mortality between sex and age groups may be 344 largely driven by a thermoregulatory pathway. Some studies suggested that men have 345 larger decreases in core body temperature when exposed to cold, and thus are more is the author/funder, who has granted medRxiv a license to display the preprint in (which was not certified by peer review) preprint The copyright holder for this this version posted September 18, 2020. There are some limitations in this study. First, we did not include the analysis of the 362 disease-specific mortality because the data was not available. Therefore, we did not 363 know the extent of the temperature impact on certain disease-specific mortality in the 364 pandemic. An additional limitation is that this is an ecological study without individual 365 data. Therefore, exposure misclassification is a potential concern. For example, the 366 aggregated ambient temperature at a province-level does not necessarily remain 367 consistent for individuals, specifically for people who may reduce the cold exposure 368 because of keeping the stay-at-home orders during the pandemic. Furthermore, we were 369 unable to make any inference in terms of the possible mechanism pathways governing 370 the association between cold exposure and excess mortality in the pandemic. is the author/funder, who has granted medRxiv a license to display the preprint in (which was not certified by peer review) preprint The copyright holder for this this version posted September 18, 2020. is the author/funder, who has granted medRxiv a license to display the preprint in (which was not certified by peer review) preprint The copyright holder for this this version posted September 18, 2020. . https://doi.org/10.1101/2020.09.15.20194944 doi: medRxiv preprint Trends in temperature-related age-specific and 385 sex-specific mortality from cardiovascular diseases in spain: A national time-series 386 analysis Reversal of the seasonality of 388 temperature-attributable mortality from respiratory diseases in spain Effects of 391 cold weather on mortality: Results from 15 european cities within the phewe project Conditional poisson models: A flexible 394 alternative to conditional logistic case cross-over analysis Out-of-hospital 397 cardiac arrest during the covid-19 outbreak in italy 399 Estimating excess 1-year mortality associated with the covid-19 pandemic according to 400 underlying conditions and age: A population-based cohort study Admissions to veterans affairs hospitals for emergency 402 conditions during the covid-19 pandemic Covid-404 19: Towards controlling of a pandemic A spatio-temporal analysis for exploring the effect 406 of temperature on covid-19 early evolution in spain 409 Effects of air temperature on climate-sensitive mortality and morbidity outcomes in the 410 elderly; a systematic review and meta-analysis of epidemiological evidence Humidity: Calculate water vapor measures from temperature and dew point The lagged 415 effect of cold temperature and wind chill on cardiorespiratory mortality in scotland Effects of air temperature 418 and relative humidity on coronavirus survival on surfaces Reduced rate of hospital admissions for acs during covid-19 outbreak in northern italy 424 Reduction of hospitalizations for myocardial infarction in italy in the covid-19 era An explanation for the seasonality of acute upper respiratory tract viral 427 infections Fair 429 allocation of scarce medical resources in the time of covid-19 Distributed lag non -linear models 433 Mortality risk attributable to high and low ambient temperature: A multicountry 434 observational study Projections 436 of temperature-related excess mortality under climate change scenarios The importance of proper death certification during the 439 covid-19 pandemic Adolescent psychiatric disorders during the covid-19 pandemic and lockdown The impact of temperature on mortality 444 in tianjin, china: A case-crossover design with a distributed lag nonlinear model Extremely cold and 447 hot temperatures increase the risk of ischaemic heart disease mortality: Epidemiological 448 evidence from china Global variation 450 in the effects of ambient temperature on mortality: A systematic evaluation 453 Temperature variability and mortality: A multi-country study Projecting future temperature-456 related mortality in three largest australian cities Potential association between covid-19 458 mortality and health-care resource availability Increases in 460 platelet and red cell counts, blood viscosity, and arterial pressure during mild surface 461 cooling: Factors in mortality from coronary and cerebral thrombosis in winter Effects of temperature variation and 464 humidity on the death of covid-19 in wuhan Out-of-hospital 467 cardiac arrest during the covid-19 pandemic in paris, france: A population-based, 468 observational study Ambient temperature and cardiovascular mortality: A systematic review and meta-471 analysis Temperature and mental health: Evidence from the spectrum 473 of mental health outcomes Istat) and the InstituteSuperiore di Sanità (Iss). 2020. 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