Ambient temperature and risk of cardiovascular hospitalization: An updated systematic review and meta-analysis

• Published in: The Science of the total environment 2016-04, Vol.550, p.1084-1102
• Main Authors: Phung, Dung, Thai, Phong K., Guo, Yuming, Morawska, Lidia, Rutherford, Shannon, Chu, Cordia
• Format: Article
• Language: English
• Subjects: Cardiovascular admission; Cardiovascular Diseases - epidemiology; Cold exposure; Diurnal temperature; Environmental Exposure - statistics & numerical data; Heatwave; Hospitalization - trends; Temperature; Temperature exposure
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/j.scitotenv.2016.01.154

The association between temperatures and risk of cardiovascular mortality has been recognized but the association drawn from previous meta-analysis was weak due to the lack of sufficient studies. This paper presented a review with updated reports in the literature about the risk of cardiovascular hospitalization in relation to different temperature exposures and examined the dose–response relationship of temperature-cardiovascular hospitalization by change in units of temperature, latitudes, and lag days. The pooled effect sizes were calculated for cold, heat, heatwave, and diurnal variation using random-effects meta-analysis, and the dose–response relationship of temperature-cardiovascular admission was modelled using random-effect meta-regression. The Cochrane Q-test and index of heterogeneity (I2) were used to evaluate heterogeneity, and Egger's test was used to evaluate publication bias. Sixty-four studies were included in meta-analysis. The pooled results suggest that for a change in temperature condition, the risk of cardiovascular hospitalization increased 2.8% (RR, 1.028; 95% CI, 1.021–1.035) for cold exposure, 2.2% (RR, 1.022; 95% CI, 1.006–1.039) for heatwave exposure, and 0.7% (RR, 1.007; 95% CI, 1.002–1.012) for an increase in diurnal temperature. However no association was observed for heat exposure. The significant dose–response relationship of temperature — cardiovascular admission was found with cold exposure and diurnal temperature. Increase in one-day lag caused a marginal reduction in risk of cardiovascular hospitalizations for cold exposure and diurnal variation, and increase in latitude was associated with a decrease in risk of cardiovascular hospitalizations for diurnal temperature only. There is a significant short-term effect of cold exposure, heatwave and diurnal variation on cardiovascular hospitalizations. Further research is needed to understand the temperature-cardiovascular relationship for different climate areas. [Display omitted] •There are significant short-term effects of cold, heatwave to CDV hospitalization.•Similar association was observed for diurnal temperature variation.•There is an inconsistent effect of heat exposure on CDV hospitalizations.•Future studies need to focus on specific geographical and climate areas.