[Relationship between daily mean temperature and emergency department visits for respiratory diseases: a time-series analysis].
OBJECTIVE
To quantitatively evaluate the influences of daily mean air temperature (DMT) on Emergency Department Visits (EDVs) for the respiratory  diseases.


METHODS
The EDV data from medical records for respiratory diseases in Peking University Third Hospital between January 2004 and June  2009 were collected. The data of the air pollutants (SO(2), NO(2) and PM(10)) and meteorological factors at the same time periods were also collected from the  local authorities of Beijing. Time-series analysis and generalized additive models (GAM) were used to explore the exposurrre-response relationship  between DMT and EDVs for respiratory diseases.


RESULTS
A total of 35 073 patients [males 14 707(41.93%,14 707/35 073), females 19 122(54.52%,19  122/35 073) and gender missing 1 244(3.55%, 1 244/35 073)] EDVs for respiratory diseases were included. The relationship between DMT and EDVs for  the respiratory diseases was mainly of "V" shape, the optimum temperature(OT) was about 4 °C and the effect of DMT was significant with a 0-3 day lag  structure for most of the models. When DMT≤OT, each 1°C decrease in DMT corresponded to 3.75% (95% CI of RR: 0.938 3-0.965 3), 3.10% (95% CI of  RR:0.949 2-0.989 1), 4.09% (95% CI of RR:0.940 7-0.977 8) increase of EDVs for the overall, male, and female, respectively. When DMT>OT, the value  caused by each increase in 1°C in DMT was 1.54% (95% CI of RR:1.006 6-1.024 3), 1.80% (95% CI of RR:1.005 3-1.030 9), and 1.51 (95% CI of RR:1.003 2- 1.027 2), respectively. The effect was statistically significant within the 0-3 day lag. When DMT≤OT, the effect was stronger for the older people, while the  effect was strongest for the 45-59 years old people.


CONCLUSIONS
The relationship between DMT and EDVs for respiratory diseases is mainly of "V" type,  with an optimum temperature of 4 °C.Both DMT decrease when DMT≤OT and increase when DMT>OT correspond to different increase of EDVs for  respiratory diseases. Low DMT has stronger effect than high DMT. Different age group and gender have different effects.
Department of Occupational and Environmental Health Science, Peking University School of Public Health, Beijing, China.
Yun-zheng
YZ
Mo
Ya-an
YA
Zheng
Hui
H
Tao
Mei-mei
MM
Xu
Guo-xing
GX
Li
Feng-ming
FM
Dong
Jun-han
JH
Liu
Xiao-chuan
XC
Pan
D000293:Adolescent; D000328:Adult; D000368:Aged; D001249:Asthma / Q000453:epidemiology; D002648:Child; D002675:Child, Preschool; D002681:China / Q000453:epidemiology; D004636:Emergency Service, Hospital / Q000706:statistics & numerical data*; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D008685:Meteorological Concepts; D008875:Middle Aged; D008962:Models, Theoretical; D029424:Pulmonary Disease, Chronic Obstructive / Q000453:epidemiology; D012140:Respiratory Tract Diseases / Q000453:epidemiology*; D012141:Respiratory Tract Infections / Q000453:epidemiology; D013696:Temperature; D055815:Young Adult