tetano
Editor, Senior Moderator
BMJ Open
. 2021 Jul 7;11(7):e044876.
doi: 10.1136/bmjopen-2020-044876.
Role of temperature, influenza and other local characteristics in seasonality of mortality: a population-based time-series study in Japan
Lina Madaniyazi[SUP] 1 2 [/SUP], Chris Fook Sheng Ng[SUP] 2 [/SUP], Xerxes Seposo[SUP] 2 [/SUP], Michiko Toizumi[SUP] 3 2 [/SUP], Lay-Myint Yoshida[SUP] 3 2 [/SUP], Yasushi Honda[SUP] 4 5 [/SUP], Ben Armstrong[SUP] 6 [/SUP], Masahiro Hashizume[SUP] 3 7 [/SUP]
Affiliations
Abstract
Objectives: To investigate the extent to which temperature and influenza explained seasonality of mortality in Japan and to examine the association of the seasonality with prefecture-specific characteristics.
Design: We conducted time-series analysis to estimate the seasonal amplitude before and after adjusting for temperature and/or influenza-like illness (ILI). Next, we applied linear mixed effect models to investigate the association of seasonal amplitudes with each indicator on prefecture-specific characteristics on climate, demographic and socioeconomic factors and adaptations.
Setting: 47 prefectures in Japan PARTICIPANTS: Deaths for all-cause, circulatory, and respiratory disease between 1999 and 2015.
Outcome measures: Peak-to-trough ratio (PTR, a measure of seasonal amplitude).
Results: The nationwide unadjusted-PTRs for all-cause, circulatory and respiratory mortality were 1.29 (95% CIs: 1.28 to 1.31), 1.55 (95% CI: 1.52 to 1.57) and 1.45 (95% CI: 1.43 to 1.48), respectively. These PTRs reduced substantially after adjusting for temperature but very little after a separate adjustment for ILI. Furthermore, seasonal amplitudes varied between prefectures. However, there was no strong evidence for the associations of PTR with the indicators on prefecture-specific characteristics.
Conclusions: Seasonality of mortality is primarily driven by temperature in Japan. The spatial variation in seasonal amplitudes was not associated with prefecture-specific characteristics. Although further investigations are required to confirm our findings, this study can help us gain a better understanding of the mechanisms underlying seasonality of mortality.
Keywords: epidemiology; preventive medicine; public health.
. 2021 Jul 7;11(7):e044876.
doi: 10.1136/bmjopen-2020-044876.
Role of temperature, influenza and other local characteristics in seasonality of mortality: a population-based time-series study in Japan
Lina Madaniyazi[SUP] 1 2 [/SUP], Chris Fook Sheng Ng[SUP] 2 [/SUP], Xerxes Seposo[SUP] 2 [/SUP], Michiko Toizumi[SUP] 3 2 [/SUP], Lay-Myint Yoshida[SUP] 3 2 [/SUP], Yasushi Honda[SUP] 4 5 [/SUP], Ben Armstrong[SUP] 6 [/SUP], Masahiro Hashizume[SUP] 3 7 [/SUP]
Affiliations
- PMID: 34233967
- DOI: 10.1136/bmjopen-2020-044876
Abstract
Objectives: To investigate the extent to which temperature and influenza explained seasonality of mortality in Japan and to examine the association of the seasonality with prefecture-specific characteristics.
Design: We conducted time-series analysis to estimate the seasonal amplitude before and after adjusting for temperature and/or influenza-like illness (ILI). Next, we applied linear mixed effect models to investigate the association of seasonal amplitudes with each indicator on prefecture-specific characteristics on climate, demographic and socioeconomic factors and adaptations.
Setting: 47 prefectures in Japan PARTICIPANTS: Deaths for all-cause, circulatory, and respiratory disease between 1999 and 2015.
Outcome measures: Peak-to-trough ratio (PTR, a measure of seasonal amplitude).
Results: The nationwide unadjusted-PTRs for all-cause, circulatory and respiratory mortality were 1.29 (95% CIs: 1.28 to 1.31), 1.55 (95% CI: 1.52 to 1.57) and 1.45 (95% CI: 1.43 to 1.48), respectively. These PTRs reduced substantially after adjusting for temperature but very little after a separate adjustment for ILI. Furthermore, seasonal amplitudes varied between prefectures. However, there was no strong evidence for the associations of PTR with the indicators on prefecture-specific characteristics.
Conclusions: Seasonality of mortality is primarily driven by temperature in Japan. The spatial variation in seasonal amplitudes was not associated with prefecture-specific characteristics. Although further investigations are required to confirm our findings, this study can help us gain a better understanding of the mechanisms underlying seasonality of mortality.
Keywords: epidemiology; preventive medicine; public health.