Short-term effect of temperature on daily emergency visits for acute myocardial infarction with threshold temperatures.
BACKGROUND
The relationship between temperature and myocardial infarction has not been fully explained. In this study, we identified the threshold temperature and examined the relationship between temperature and emergency admissions due to MI in Korea.


METHODS
Poisson generalized additive model analyses were used to assess the short-term effects of temperature (mean, maximum, minimum, diurnal) on MI emergency visits, after controlling for meteorological variable and air pollution (PM10, NO2). We defined the threshold temperature when the inflection point showed a statistically significant difference in the regression coefficients of the generalized additive models (GAMs) analysis. The analysis was performed on the following subgroups: geographical region, gender, age (<75 years or ≥ 75 years), and MI status (STEMI or non-STEMI).


RESULTS
The threshold temperatures during heat exposure were for the maximum temperature as 25.5-31.5°C and for the mean temperature as 27.5-28.5°C. The threshold temperatures during cold exposure were for the minimum temperature as -2.5-1.5°C. Relative risks (RRs) of emergency visits above hot temperature thresholds ranged from 1.02 to 1.30 and those below cold temperature thresholds ranged from 1.01 to 1.05. We also observed increased RRs ranged from 1.02 to 1.65 of emergency visits when temperatures changes on a single day or on successive days.


CONCLUSIONS
We found a relationship between temperature and MI occurrence during both heat and cold exposure at the threshold temperature. Diurnal temperature or temperature change on successive days also increased MI risk.
Department of Public Health, Graduate School, Korea University, Seoul, South Korea; Graduate School of Public Health, Graduate School, Korea University, Seoul, Korea.
Suji
S
Lee
Department of Public Health, Graduate School, Korea University, Seoul, South Korea; Department of Preventive Medicine, College of medicine, Korea University, Seoul, Korea; Graduate School of Public Health, Graduate School, Korea University, Seoul, Korea.
Eunil
E
Lee
Department of Statistics, Sungshin Women's University College of Natural sciences, Seoul, Korea.
Man Sik
MS
Park
Department of Public Health, Graduate School, Korea University, Seoul, South Korea; Graduate School of Public Health, Graduate School, Korea University, Seoul, Korea.
Bo Yeon
BY
Kwon
Department of Statistics, Sungshin Women's University College of Natural sciences, Seoul, Korea.
Hana
H
Kim
Graduate School of Public Health, Graduate School, Korea University, Seoul, Korea.
Dea Ho
DH
Jung
Graduate School of Public Health, Graduate School, Korea University, Seoul, Korea.
Kyung Hee
KH
Jo
Department of Cardiology, Chonnam National University Hospital, Gwangju, Korea.
Myung Ho
MH
Jeong
Cardiovascular Center, Korea University Guro Hospital, Seoul, Korea.
Seung-Woon
SW
Rha
D000208:Acute Disease; D000368:Aged; D002980:Climate; D004636:Emergency Service, Hospital / Q000706:statistics & numerical data; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000453:epidemiology* / Q000628:therapy; D056910:Republic of Korea / Q000453:epidemiology; D012306:Risk; D012621:Seasons; D017678:Sex Distribution; D013696:Temperature