title: Low Ambient Temperature and Intracerebral Hemorrhage: The INTERACT2 Study.
abstract: BACKGROUND
  Rates of acute intracerebral hemorrhage (ICH) increase in winter months but the magnitude of risk is unknown. We aimed to quantify the association of ambient temperature with the risk of ICH in the Intensive Blood Pressure Reduction in Acute Cerebral Haemorrhage Trial (INTERACT2) participants on an hourly timescale.
  
  
  METHODS
  INTERACT2 was an international, open, blinded endpoint, randomized controlled trial of patients with spontaneous ICH (<6h of onset) and elevated systolic blood pressure (SBP, 150-220 mmHg) assigned to intensive (target SBP <140 mmHg) or guideline-recommended (SBP <180 mmHg) BP treatment. We linked individual level hourly temperature to baseline data of 1997 participants, and performed case-crossover analyses using a distributed lag non-linear model with 24h lag period to assess the association of ambient temperature and risk of ICH. Results were presented as overall cumulative odds ratios (ORs) and 95% CI.
  
  
  RESULTS
  Low ambient temperature (≤10°C) was associated with increased risks of ICH: overall cumulative OR was 1.37 (0.99-1.91) for 10°C, 1.92 (1.31-2.81) for 0°C, 3.13 (1.89-5.19) for -10°C, and 5.76 (2.30-14.42) for -20°C, as compared with a reference temperature of 20°C.There was no clear relation of low temperature beyond three hours after exposure. Results were consistent in sensitivity analyses.
  
  
  CONCLUSIONS
  Exposure to low ambient temperature within several hours increases the risk of ICH.
  
  
  BACKGROUND
  ClinicalTrials.gov NCT00716079.
authors: Division of Neurology and Mental health, The George Institute for Global Health, Sydney, New South Wales, Australia.|Sydney Medical School, the University of Sydney, Sydney, New South Wales, Australia.
authors: Danni
authors: D
authors: Zheng
authors: Division of Neurology and Mental health, The George Institute for Global Health, Sydney, New South Wales, Australia.|Sydney Medical School, the University of Sydney, Sydney, New South Wales, Australia.|Centre for Epidemiologic Research in Asia, Shiga University of Medical Sciences, Shiga University, Shiga, Japan.
authors: Hisatomi
authors: H
authors: Arima
authors: Division of Neurology and Mental health, The George Institute for Global Health, Sydney, New South Wales, Australia.
authors: Shoichiro
authors: S
authors: Sato
authors: Department of Social and Environmental Health Research, London School of Hygiene & Tropical Medicine, London, United Kingdom.
authors: Antonio
authors: A
authors: Gasparrini
authors: Sydney Medical School, the University of Sydney, Sydney, New South Wales, Australia.
authors: Emma
authors: E
authors: Heeley
authors: Division of Neurology and Mental health, The George Institute for Global Health, Sydney, New South Wales, Australia.|Sydney Medical School, the University of Sydney, Sydney, New South Wales, Australia.|Royal Prince Alfred Hospital, Camperdown, New South Wales, Australia.
authors: Candice
authors: C
authors: Delcourt
authors: Sydney Medical School, the University of Sydney, Sydney, New South Wales, Australia.
authors: Serigne
authors: S
authors: Lo
authors: Department of Neurology, Peking University First Hospital, Beijing, China.
authors: Yining
authors: Y
authors: Huang
authors: Centre for Epidemiological Studies and Clinical Trials, The Shanghai Institute of Hypertension, Ruijin Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, China.
authors: Jiguang
authors: J
authors: Wang
authors: Department of Neurology, APHP-Hôpital Lariboisière, DHU NeuroVasc Paris-Sorbonne, Université Paris Diderot-Sorbonne Paris Cité, Paris, France.|Department of Neuroscience, CRCHUM, University of Montreal, Montreal, Quebec, Canada.
authors: Christian
authors: C
authors: Stapf
authors: Department of Cardiovascular Sciences and NIHR Biomedical Research Unit in Cardiovascular Disease, University of Leicester, Leicester, United Kingdom.
authors: Thompson
authors: T
authors: Robinson
authors: Vascular Neurology Program, Neurology Services, Department of Internal Medicine, Clínica Alemana de Santiago, Universidad del Desarrollo, Santiago, Chile.
authors: Pablo
authors: P
authors: Lavados
authors: Division of Neurology and Mental health, The George Institute for Global Health, Sydney, New South Wales, Australia.
authors: John
authors: J
authors: Chalmers
authors: Division of Neurology and Mental health, The George Institute for Global Health, Sydney, New South Wales, Australia.|Sydney Medical School, the University of Sydney, Sydney, New South Wales, Australia.|Royal Prince Alfred Hospital, Camperdown, New South Wales, Australia.
authors: Craig S
authors: CS
authors: Anderson
mesh_terms: D000368:Aged; D001794:Blood Pressure / Q000502:physiology; D002543:Cerebral Hemorrhage / Q000209:etiology*; D003080:Cold Temperature / Q000009:adverse effects*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012307:Risk Factors