Association between high and low ambient temperature and out-of-hospital cardiac arrest with cardiac etiology in Japan: a case-crossover study

Environmental Health and Preventive Medicine, Jul 2017

Objective The objective of the study was to examine the association between high and low temperature and out-of-hospital cardiac arrest (OHCA) with cardiac etiology. Methods The study was conducted under a case-crossover design. Subjects were 97,500 patients aged 40 years or older with OHCA having a cardiac etiology in Tokyo, Osaka, and Fukuoka Prefecture from 2005 to 2012. We used national data with an Utstein-style resuscitation registration. Temperature was categorized into five categories with cut points of 5, 10, 24, and 30 °C. The reference category was 10–23.9 °C. Conditional logistic regression was used with adjustment for daily means of relative humidity, atmospheric pressure, and wind speed and daily amount of precipitation and hours of daylight. Results Exposure to high temperature (≥30 °C) increased the risk of OHCA (OR = 1.11, 95% confidence interval (CI) 1.04–1.18). Further, low temperature (<5 °C) and relatively low temperature (5–9.9 °C) were also associated with OHCA (OR = 1.20, 95% CI 1.16–1.25; OR = 1.10, 95% CI 1.07–1.13, respectively). The temperature-OHCA association curves were U-shaped or J-shaped, and the association was more prominent among those aged 80 years or older. Conclusion This study shows that the occurrence of OHCA with cardiac etiology is associated with low temperature. In addition, the occurrence is also associated with high temperature in those aged 80 years or older.

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Association between high and low ambient temperature and out-of-hospital cardiac arrest with cardiac etiology in Japan: a case-crossover study

Yamazaki and Michikawa Environmental Health and Preventive Medicine Association between high and low ambient temperature and out-of-hospital cardiac arrest with cardiac etiology in Japan: a case-crossover study Shin Yamazaki 0 Takehiro Michikawa 0 0 Environmental Epidemiology Section, Centre for Health and Environmental Risk Research, National Institute for Environmental Studies , Onogawa 16-2, Tsukuba 305-8506 , Japan Objective: The objective of the study was to examine the association between high and low temperature and outof-hospital cardiac arrest (OHCA) with cardiac etiology. Methods: The study was conducted under a case-crossover design. Subjects were 97,500 patients aged 40 years or older with OHCA having a cardiac etiology in Tokyo, Osaka, and Fukuoka Prefecture from 2005 to 2012. We used national data with an Utstein-style resuscitation registration. Temperature was categorized into five categories with cut points of 5, 10, 24, and 30 °C. The reference category was 10-23.9 °C. Conditional logistic regression was used with adjustment for daily means of relative humidity, atmospheric pressure, and wind speed and daily amount of precipitation and hours of daylight. Results: Exposure to high temperature (≥30 °C) increased the risk of OHCA (OR = 1.11, 95% confidence interval (CI) 1.04-1.18). Further, low temperature (<5 °C) and relatively low temperature (5-9.9 °C) were also associated with OHCA (OR = 1.20, 95% CI 1.16-1.25; OR = 1.10, 95% CI 1.07-1.13, respectively). The temperature-OHCA association curves were U-shaped or J-shaped, and the association was more prominent among those aged 80 years or older. Conclusion: This study shows that the occurrence of OHCA with cardiac etiology is associated with low temperature. In addition, the occurrence is also associated with high temperature in those aged 80 years or older. Introduction Many studies have provided estimates of death attributable to either heat or cold [ 1, 2 ]. For example, a multicountry study showed that mortality risk increased slowly for cold temperatures below the minimum mortality temperature and quickly at high temperature [3]. With regard to death caused by cardiovascular disease, a large American study found that 2-day mean extreme high and low temperatures were associated with increased risk of death [ 4 ]. In addition, a Chinese study showed that out-of-hospital coronary death (OHCD) from the Chinese death register was associated with 14day mean temperature. The temperature-OHCD association curves in that study were U- or J-shaped and showed that extreme temperature significantly increased the risk of OHCD [ 5 ]. In contrast, a systematic review pointed out that the effects of temperature on cardiorespiratory morbidity appeared to be smaller and more variable than previous findings related to cardiorespiratory mortality [ 6 ]. In Japan, the occurrence of adult cases of out-of-hospital cardiac arrest (OHCA) with cardiac etiology increases with decreasing temperature during the day, in elderly people in particular [ 7 ]. Japan is presently aging more rapidly than any other country in the world. In 2014, the percentage of the population aged 65 and over (percentage of elderly) was 26.0% (previous year: 25.1%) and 12.5% for that aged 75 years old and over (the old elderly; 15.92 million people) [ 8 ]. With the progress of aging, it is expected that the number of people experiencing OHCA will increase. A previous Japanese study suggested that the frequency of OHCA with cardiac etiology increases with decreasing temperature during the day [ 7 ]. However, analysis on the effect of extremely hot temperature on OHCA in that study was insufficient. Here, we examined the association between extreme hot and cold temperatures and OHCA with cardiac etiology in Japan. Methods Study design The study was conducted under a time-stratified casecrossover design, which is typically used to assess brief changes in risk associated with transient exposures [ 9, 10 ]. Case-crossover studies can be regarded as a special type of case-control study in which each case serves as its own control, thereby providing inherent control of potential confounding by fixed individual characteristics such as sex, race, diet, and age. “Time-stratified” indicates the method by which the control periods were chosen. Specifically, we stratified time into months to select days for control periods that fell on the same day of the week within the same month as the date of the occurrence of OHCA (day of the index period). Data collection We used national data with an Utstein-style resuscitation registration. Subjects were patients with OHCA of presumed cardiac origin who were treated by emergency medical service personnel in Tokyo, Osaka, and Fukuoka Prefecture from January 1, 2005, to December 31, 2012. We restricted subject age to 40 years or older. The data were obtained from the Japanese Fire and Disaster Management Agency. Outcome was the occurr (...truncated)


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Shin Yamazaki, Takehiro Michikawa. Association between high and low ambient temperature and out-of-hospital cardiac arrest with cardiac etiology in Japan: a case-crossover study, Environmental Health and Preventive Medicine, 2017, pp. 1-5, Volume 22, Issue 1, DOI: 10.1186/s12199-017-0669-9