title: Ambient Temperature and Stroke Occurrence: A Systematic Review and Meta-Analysis.
abstract: Biologically plausible associations exist between climatic conditions and stroke risk, but study results are inconsistent. We aimed to summarize current evidence on ambient temperature and overall stroke occurrence, and by age, sex, and variation of temperature. We performed a systematic literature search across MEDLINE, Embase, PsycINFO, CINAHL, Web of Science, and GEOBASE, from inception to 16 October 2015 to identify all population-based observational studies. Where possible, data were pooled for meta-analysis with Odds ratios (OR) and corresponding 95% confidence intervals (CI) by means of the random effects meta-analysis. We included 21 studies with a total of 476,511 patients. The data were varied as indicated by significant heterogeneity across studies for both ischemic stroke (IS) and intracerebral hemorrhage (ICH). Pooled OR (95% CI) in every 1 degree Celsius increase in ambient temperature was significant for ICH 0.97 (0.94-1.00), but not for IS 1.00 (0.99-1.01) and subarachnoid hemorrhage (SAH) 1.00 (0.98-1.01). Meta-analysis was not possible for the pre-specified subgroup analyses by age, sex, and variation of temperature. Change in temperature over the previous 24 h appeared to be more important than absolute temperature in relation to the risk of stroke, especially in relation to the risk of ICH. Older age appeared to increase vulnerability to low temperature for both IS and ICH. To conclude, this review shows that lower mean ambient temperature is significantly associated with the risk of ICH, but not with IS and SAH. Larger temperature changes were associated with higher stroke rates in the elderly.
authors.affiliation: The George Institute for Global Health and Royal Prince Alfred Hospital, the University of Sydney, P.O. Box M201, Missenden Road, Sydney, NSW 2050, Australia. xwang@georgeinstitute.org.au.|Sydney Medical School, the University of Sydney, Sydney, NSW 2006, Australia. xwang@georgeinstitute.org.au.
authors.forename: Xia
authors.initials: X
authors.lastname: Wang
authors.affiliation: The George Institute for Global Health and Royal Prince Alfred Hospital, the University of Sydney, P.O. Box M201, Missenden Road, Sydney, NSW 2050, Australia. yongjuncao@126.com.|Department of Neurology, the Second Affiliated Hospital of Soochow University, No. 1055, Sanxiang Rd., Suzhou 215004, China. yongjuncao@126.com.
authors.forename: Yongjun
authors.initials: Y
authors.lastname: Cao
authors.affiliation: The George Institute for Global Health and Royal Prince Alfred Hospital, the University of Sydney, P.O. Box M201, Missenden Road, Sydney, NSW 2050, Australia. dhong@georgeinstitute.org.au.|Division of Nephrology, Sichuan Academy of Medical Sciences &amp; Sichuan Provincial People's Hospital, Chengdu 610072, China. dhong@georgeinstitute.org.au.
authors.forename: Daqing
authors.initials: D
authors.lastname: Hong
authors.affiliation: The George Institute for Global Health and Royal Prince Alfred Hospital, the University of Sydney, P.O. Box M201, Missenden Road, Sydney, NSW 2050, Australia. dzheng@georgeinstitute.org.au.|Sydney Medical School, the University of Sydney, Sydney, NSW 2006, Australia. dzheng@georgeinstitute.org.au.
authors.forename: Danni
authors.initials: D
authors.lastname: Zheng
authors.affiliation: The George Institute for Global Health and Royal Prince Alfred Hospital, the University of Sydney, P.O. Box M201, Missenden Road, Sydney, NSW 2050, Australia. srichtering@georgeinstitute.org.au.
authors.forename: Sarah
authors.initials: S
authors.lastname: Richtering
authors.affiliation: Department of Neurology, Oslo University Hospital, Oslo 0424, Norway. else@sandset.net.
authors.forename: Else Charlotte
authors.initials: EC
authors.lastname: Sandset
authors.affiliation: The George Institute for Global Health and Royal Prince Alfred Hospital, the University of Sydney, P.O. Box M201, Missenden Road, Sydney, NSW 2050, Australia. hugh-96@hotmail.com.
authors.forename: Tzen Hugh
authors.initials: TH
authors.lastname: Leong
authors.affiliation: Department of Preventive Medicine and Public Health, Faculty of Medicine, Fukuoka University, Fukuoka 814-0180, Japan. harima@georgeinstitute.org.au.
authors.forename: Hisatomi
authors.initials: H
authors.lastname: Arima
authors.affiliation: The George Institute for Global Health and Royal Prince Alfred Hospital, the University of Sydney, P.O. Box M201, Missenden Road, Sydney, NSW 2050, Australia. sIslam@georgeinstitute.org.au.
authors.forename: Shariful
authors.initials: S
authors.lastname: Islam
authors.affiliation: The George Institute for Global Health and Royal Prince Alfred Hospital, the University of Sydney, P.O. Box M201, Missenden Road, Sydney, NSW 2050, Australia. asalam@georgeinstitute.org.au.
authors.forename: Abdul
authors.initials: A
authors.lastname: Salam
authors.affiliation: The George Institute for Global Health and Royal Prince Alfred Hospital, the University of Sydney, P.O. Box M201, Missenden Road, Sydney, NSW 2050, Australia. canderson@georgeinstitute.org.au.|Sydney Medical School, the University of Sydney, Sydney, NSW 2006, Australia. canderson@georgeinstitute.org.au.
authors.forename: Craig
authors.initials: C
authors.lastname: Anderson
authors.affiliation: Department of Cardiovascular Sciences and NIHR Biomedical Research Unit for Cardiovascular Diseases, University of Leicester, Leicester LE1 7RH, UK. tgr2@leicester.ac.uk.
authors.forename: Thompson
authors.initials: T
authors.lastname: Robinson
authors.affiliation: The George Institute for Global Health and Royal Prince Alfred Hospital, the University of Sydney, P.O. Box M201, Missenden Road, Sydney, NSW 2050, Australia. mhackett@georgeinstitute.org.au.|College of Health and Wellbeing, the University of Central Lancashire, Preston PR1 2HE, UK. mhackett@georgeinstitute.org.au.
authors.forename: Maree L
authors.initials: ML
authors.lastname: Hackett
mesh_terms: D000367:Age Factors; D000368:Aged; D005260:Female; D006801:Humans; D008297:Male; D016017:Odds Ratio; D012307:Risk Factors; D012737:Sex Factors; D020521:Stroke / Q000453:epidemiology*; D013696:Temperature
keywords: stroke; systematic review; temperature; weather