title: Impact of ambient temperature on morbidity and mortality: An overview of reviews.
abstract: The objectives were (i) to conduct an overview of systematic reviews to summarize evidence from and evaluate the methodological quality of systematic reviews assessing the impact of ambient temperature on morbidity and mortality; and (ii) to reanalyse meta-analyses of cold-induced cardiovascular morbidity in different age groups. The registration number is PROSPERO-CRD42016047179. PubMed, Embase, the Cochrane Library, Web of Science, the Cumulative Index to Nursing and Allied Health Literature (CINAHL), and Global Health were systematically searched to identify systematic reviews. Two reviewers independently selected studies for inclusion, extracted data, and assessed quality. The Assessment of Multiple Systematic Reviews (AMSTAR) checklist was used to assess the methodological quality of included systematic reviews. Estimates of morbidity and mortality risk in association with heat exposure, cold exposure, heatwaves, cold spells and diurnal temperature ranges (DTRs) were the primary outcomes. Twenty-eight systematic reviews were included in the overview of systematic reviews. (i) The median (interquartile range) AMSTAR scores were 7 (1.75) for quantitative reviews and 3.5 (1.75) for qualitative reviews. (ii) Heat exposure was identified to be associated with increased risk of cardiovascular, cerebrovascular and respiratory mortality, but was not found to have an impact on cardiovascular or cerebrovascular morbidity. (iii) Reanalysis of the meta-analyses indicated that cold-induced cardiovascular morbidity increased in youth and middle-age (RR=1.009, 95% CI: 1.004-1.015) as well as the elderly (RR=1.013, 95% CI: 1.007-1.018). (iv) The definitions of temperature exposure adopted by different studies included various temperature indicators and thresholds. In conclusion, heat exposure seemed to have an adverse effect on mortality and cold-induced cardiovascular morbidity increased in the elderly. Developing definitions of temperature exposure at the regional level may contribute to more accurate evaluations of the health effects of temperature.
authors.affiliation: Key Laboratory for Semi-Arid Climate Change of the Ministry of Education, College of Atmospheric Sciences, Lanzhou University, Lanzhou 730000, China. Electronic address: songxp15@lzu.edu.cn.
authors.forename: Xuping
authors.initials: X
authors.lastname: Song
authors.affiliation: Mountain Environment and Meteorology Key Laboratory of Education Bureau of Sichuan Province, College of Atmospheric Sciences, Chengdu University of Information Technology, Chengdu 610225, China; Key Laboratory for Semi-Arid Climate Change of the Ministry of Education, College of Atmospheric Sciences, Lanzhou University, Lanzhou 730000, China. Electronic address: wangsg@lzu.edu.cn.
authors.forename: Shigong
authors.initials: S
authors.lastname: Wang
authors.affiliation: Key Laboratory for Semi-Arid Climate Change of the Ministry of Education, College of Atmospheric Sciences, Lanzhou University, Lanzhou 730000, China. Electronic address: huyl10@lzu.edu.cn.
authors.forename: Yuling
authors.initials: Y
authors.lastname: Hu
authors.affiliation: Key Laboratory for Semi-Arid Climate Change of the Ministry of Education, College of Atmospheric Sciences, Lanzhou University, Lanzhou 730000, China. Electronic address: yuem15@lzu.edu.cn.
authors.forename: Man
authors.initials: M
authors.lastname: Yue
authors.affiliation: School and Hospital of Stomatology, Wuhan University, Wuhan 430079, China. Electronic address: lucky@whu.edu.cn.
authors.forename: Tingting
authors.initials: T
authors.lastname: Zhang
authors.affiliation: School of Public Health, Lanzhou University, Lanzhou 730000, China. Electronic address: yuliu14@lzu.edu.cn.
authors.forename: Yu
authors.initials: Y
authors.lastname: Liu
authors.affiliation: Evidence Based Medicine Center, School of Basic Medical Sciences, Lanzhou University, Lanzhou 730000, China. Electronic address: tjh996@163.com.
authors.forename: Jinhui
authors.initials: J
authors.lastname: Tian
authors.affiliation: Key Laboratory for Semi-Arid Climate Change of the Ministry of Education, College of Atmospheric Sciences, Lanzhou University, Lanzhou 730000, China. Electronic address: shangkz@lzu.edu.cn.
authors.forename: Kezheng
authors.initials: K
authors.lastname: Shang
mesh_terms: D000068598:Data Accuracy; D006801:Humans; D009017:Morbidity; D009026:Mortality; D012196:Review Literature as Topic; D013696:Temperature
keywords: Health; Systematic review; Temperature