Risk of Out-of-Hospital Cardiac Arrest in Aged Individuals in Relation to Cold Ambient Temperature　― A Report From North Tochigi Experience ―

Abstract

A nnually, out-of-hospital cardiac arrest (OHCA) occurs in over 120,000 individuals in Japan, and approximately 80% of these occur indoors. 1 Moreover, in approximately 70% of OHCA the subject is an elderly individual over 70 years old, and the survival rate with favorable neurological outcome is low. 1 Recently, an association between atmospheric conditions and the occurrence of OHCA was reported. 2 Furthermore, previous study has reported a relationship between colder temperature and the development of myocardial infarction. 3 Other studies have also shown that ischemic and hemorrhagic stroke hospital admissions are associated with extreme cold temperatures, and that the incidence of type A acute aortic dissection is associated with lower minimum temperature. 4,5However, with regard to elderly individuals, the rela-Background: The impact of cold ambient temperature on out-of-hospital cardiac arrest (OHCA) in aged individuals caused by cardiovascular events in indoor environments has not been investigated sufficiently. Methods and Results:We conducted a case-crossover study. The relationship between OHCA caused by cardiovascular events and exposure to minimum temperature <0°C was analyzed. Conditional logistic regression analysis was performed to estimate the odds ratios for the relationship between exposure to minimum temperature <0°C and the risk of OHCA. Between January 1, 2011, and December 31, 2015, a total of 1,452 cases of OHCA were documented, and patients were screened for enrollment. A total of 458 individuals were enrolled in this analysis, and were divided into 2 groups of 110 (elderly group: 65-74 years old) and 348 (aged group: ≥75 years old). The aged individuals had a significant increased risk of OHCA after exposure to minimum temperature <0°C (odds ratio [OR]: 1.528, 95% confidence interval [CI] 1.009-2.315, P=0.045). Cold ambient temperature was an especially significant increased risk for OHCA occurrence for males (OR: 1.997, 95% CI 1.036-3.773, P=0.039) and during winter (OR: 2.391, 95% CI 1.312-4.360, P=0.004) in the aged group. Conclusions: Cold ambient temperature significantly affected aged individuals (≥75 years old) experiencing an OHCA caused by cardiovascular events in indoor environments.

Machine learning algorithms for predicting days of high incidence with out-of-hospital cardiac arrest

“…Our SHAP analysis revealed that the major factors affecting OHCA incidence were low mean ambient temperature, the diurnal temperature of the previous day, month, percentage of the elderly population, and the day of the week. The result showing the link between low average temperature in the winter season and high OHCA incidence is in line with that reported in previous studies [16][17][18]. Even though exposure to cold weather was a major factor in the seasonality of OHCA incidence, the incidence peaked in January rather than February, in which the average temperature was the lowest of the year.…”

Effect of Temperature on Emergency Ambulance Call-Outs for Cardiovascular Causes: A Scoping Review

“…Other designs included case-crossover studies, − a prospective observational study, a cross-sectional study and an ecological time series study . The method of statistical analysis varied with the study design.…”

“…The spatial setting of the studies covered differing levels, ranging from suburban to urban ,,− and regional − ,,− to national , − providing information on the effects of temperature in different climatic areas.…”

“…To estimate the effects, most studies used the minimal morbidity temperature (MMT) calculated after obtaining exposure–response models, ,,− ,,,,,− with the rest using temperature ranges or selecting arbitrary thresholds to estimate the effects in some versus others ,,,,− ,,− ,, or assessing increases in risk by referring to comparable time periods during which the target exposure did not take place. ,,,− …”

“…Out-of-hospital cardiac arrest is the most widely studied cardiovascular event in ten studies. ,,,,,,,,, The majority of these papers (7/10) focus on the impact of high and low temperatures, with only one exclusively assessing the effect of low temperatures and two examining the effect of high temperatures and heat waves. , An increased risk of cardiac arrest was consistently associated with low temperatures . In eight out of nine studies, a rise in the number of call-outs following exposure to low temperatures was observed.…”