[Relationship between temperature and the risks of mortality in China: a Meta-analysis]

To understand the effect of temperature on the risk of mortality and the modification effect of latitude, in China.

Relevant papers were searched and Meta-analysis was used to determine the exposure-response relationship for each health outcome which was associated with the exposure to temperature. Meta-regression analysis was used to evaluate the effect modification by latitude.

Ten studies in 15 cities were included in the study. When temperature increased by one centigrade, the risks of mortality showed the following changes:deaths from non-accidental increased by 2% (95%CI:1%, 3%), from cardiovascular disease increased by 4% (95%CI:2%, 6%)and from the respiratory disease increased by 2% (95%CI:1%, 4%). As temperature decreased by one centigrade, the mortality risks of the following diseases showed the changes as: non-accidental death increased by 4% (95% CI:2%, 7%), cardiovascular disease increased by 4% (95%CI:1%, 7%)and the respiratory diseases increased by 2% (95%CI:0%, 4%). When latitude ranged from 0 to 25, 26 to 30, 31 to 39 degree or over 40 degrees, respectively and the temperature decreased by one centigrade, the mortality risks of the general population increased by 6.5% (95%CI:-2.7%, 15.6%), 5.8% (95% CI:2.4%, 9.3%),0.8% (95%CI:0.4%, 1.2%),0.5% (95%CI: -0.5%, 1.5%). As temperature increased by one centigrade, mortality risk of the general population increased by 0.6% (95%CI:-0.3%, 1.4%), 1.9% (95%CI:0.7%, 3.1%), 2.0% (95%CI:1.0%, 3.0%) and 5.8% (95% CI:-3.2%, 14.8%). As latitude increased by five degrees with high temperature, the mortality risk of general people increased by 0.3% (95% CI:0.1% ,0.8%) while decreased by 0.8% (95% CI:0.5%, 0.9%) under low temperature.

In China, the mortality risk increased along with the changes of temperature. The adaptability to coldness among people living in high latitude areas seemed to be stronger than those living in other areas of latitudes. Who were more vulnerable to high temperature.