The impact of the 2008 cold spell on mortality in Shanghai, China

No prior studies in China have investigated the health impact of cold spell. In Shanghai, we defined the cold spell as a period of at least seven consecutive days with daily temperature below the third percentile during the study period (2001-2009). Between January 2001 and December 2009, we identified a cold spell between January 27 and February 3, 2008 in Shanghai. We investigated the impact of cold spell on mortality of the residents living in the nine urban districts of Shanghai. We calculated the excess deaths and rate ratios (RRs) during the cold spell and compared these data with a winter reference period (January 6-9, and February 28 to March 2). The number of excess deaths during the cold spell period was 153 in our study population. The cold spell caused a short-term increase in total mortality of 13 % (95 % CI: 7-19 %). The impact was statistically significant for cardiovascular mortality (RR = 1.21, 95 % CI: 1.12-1.31), but not for respiratory mortality (RR = 1.14, 95 % CI: 0.98-1.32). For total mortality, gender did not make a statistically significant difference for the cold spell impact. Cold spell had a significant impact on mortality in elderly people (over 65 years), but not in other age groups. Conclusively, our analysis showed that the 2008 cold spell had a substantial effect on mortality in Shanghai. Public health programs should be tailored to prevent cold-spell-related health problems in the city.