title: The Role of Influenza in the Delay between Low Temperature and Ischemic Heart Disease: Evidence from Simulation and Mortality Data from Japan.
abstract: Many studies have found that cardiovascular deaths mostly occur within a few days of exposure to heat, whereas cold-related deaths can occur up to 30 days after exposure. We investigated whether influenza infection could explain the delayed cold effects on ischemic heart diseases (IHD) as they can trigger IHD. We hypothesized two pathways between cold exposure and IHD: a direct pathway and an indirect pathway through influenza infection. We created a multi-state model of the pathways and simulated incidence data to examine the observed delayed patterns in cases. We conducted cross-correlation and time series analysis with Japanese daily pneumonia and influenza (P&amp;I) mortality data to help validate our model. Simulations showed the IHD incidence through the direct pathway occurred mostly within 10 days, while IHD through influenza infection peaked at 4-6 days, followed by delayed incidences of up to 20-30 days. In the mortality data from Japan, P&amp;I lagged IHD in cross-correlations. Time series analysis showed strong delayed cold effects in the older population. There was also a strong delay on intense days of influenza which was more noticeable in the older population. Influenza can therefore be a plausible explanation for the delayed association between cold exposure and cardiovascular mortality.
authors.affiliation: School of Public Health and Social Work, Queensland University of Technology, 60 Musk Avenue, Brisbane QLD 4064, Australia. chisato.imai@gmail.com.|Department of Pediatric Infectious Diseases, Institute of Tropical Medicine, Nagasaki University, 1-12-4 Sakamoto, Nagasaki 852-8523, Japan. chisato.imai@gmail.com.
authors.forename: Chisato
authors.initials: C
authors.lastname: Imai
authors.affiliation: School of Public Health and Social Work, Queensland University of Technology, 60 Musk Avenue, Brisbane QLD 4064, Australia. a.barnett@qut.edu.au.
authors.forename: Adrian G
authors.initials: AG
authors.lastname: Barnett
authors.affiliation: Department of Pediatric Infectious Diseases, Institute of Tropical Medicine, Nagasaki University, 1-12-4 Sakamoto, Nagasaki 852-8523, Japan. hashizum@nagasaki-u.ac.jp.
authors.forename: Masahiro
authors.initials: M
authors.lastname: Hashizume
authors.affiliation: Faculty of Health and Sport Science, The University of Tsukuba, Comprehensive Research Building D, 1-1-1 Tennoudai, Tsukuba 305-8577, Japan. honda@taiiku.tsukuba.ac.jp.
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Honda
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002423:Cause of Death; D003080:Cold Temperature / Q000009:adverse effects*; D003430:Cross-Sectional Studies; D005260:Female; D006358:Hot Temperature / Q000009:adverse effects*; D006801:Humans; D015994:Incidence; D007251:Influenza, Human / Q000150:complications* / Q000453:epidemiology / Q000401:mortality*; D007564:Japan / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D017202:Myocardial Ischemia / Q000453:epidemiology / Q000209:etiology* / Q000401:mortality*; D018570:Risk Assessment; D055815:Young Adult
keywords: cold; influenza; ischemic heart disease; mortality; temperature