title: Ambient temperature and risk of cardiovascular hospitalization: An updated systematic review and meta-analysis.
abstract: 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 (I(2)) 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.
authors.affiliation: Centre for Environment and Population Health, Griffith University, Australia. Electronic address: d.phung@griffith.edu.au.
authors.forename: Dung
authors.initials: D
authors.lastname: Phung
authors.affiliation: International Laboratory for Air Quality & Health, Queensland University of Technology, Australia. Electronic address: phong.thai@qut.edu.au.
authors.forename: Phong K
authors.initials: PK
authors.lastname: Thai
authors.affiliation: Division of Epidemiology and Biostatistics, School of Public Health, University of Queensland, Australia.
authors.forename: Yuming
authors.initials: Y
authors.lastname: Guo
authors.affiliation: International Laboratory for Air Quality & Health, Queensland University of Technology, Australia.
authors.forename: Lidia
authors.initials: L
authors.lastname: Morawska
authors.affiliation: Centre for Environment and Population Health, Griffith University, Australia.
authors.forename: Shannon
authors.initials: S
authors.lastname: Rutherford
authors.affiliation: Centre for Environment and Population Health, Griffith University, Australia.
authors.forename: Cordia
authors.initials: C
authors.lastname: Chu
mesh_terms: D002318:Cardiovascular Diseases / Q000453:epidemiology*; D004781:Environmental Exposure / Q000706:statistics & numerical data*; D006760:Hospitalization / Q000639:trends*; D013696:Temperature
keywords: Cardiovascular admission; Cold exposure; Diurnal temperature; Heatwave; Temperature exposure