Wednesday, April 30, 2014

Geomagnetic Storms Can Trigger Stroke

Geomagnetic Storms Can Trigger Stroke

Evidence From 6 Large Population-Based Studies in Europe and Australasia

  1. for the International Stroke Incidence Studies Data Pooling Project Collaborators
+Author Affiliations
  1. From the National Institute for Stroke and Applied Neurosciences (V.L.F., P.G.P., R.K.) and Knowledge Engineering and Discovery Research Institute (N.K.), Auckland University of Technology, Auckland, New Zealand; School of Psychology, The University of Auckland, Auckland, New Zealand (S.B.-C.); Clinical Trial Service Unit and Epidemiological Studies Unit, Nuffield Department of Population Health (D.A.B.) and University Department of Clinical Neurology (P.M.R.), University of Oxford, Oxford, United Kingdom; Neurological and Mental Health Division at the George Institute for Global Health, Royal Prince Alfred Hospital, University of Sydney, Sydney, Australia (C.S.A.); Department of Medicine, Southern Clinical School, Monash University Melbourne, Melbourne, Australia (A.G.T.); Department of Public Health and Clinical Medicine, Umeå University, Umeå, Sweden (B.S.); Service de Neurologie, Centre Hospitalo-Universitaire, Dijon, France (M.G.); University Hospital and Faculty of Medicine of Dijon, EA 4183, University of Burgundy, Stroke Registry of Dijon (Inserm and Invs), Dijon, France (Y.B.); and Centre of Human Aerospace and Physiological Science, King’s College London, London, United Kingdom (P.C.).
  1. Correspondence to Valery L. Feigin, MD, MSc, PhD, National Institute for Stroke and Applied Neurosciences, School of Rehabilitation and Occupation Studies, Faculty of Health and Environmental Studies, Auckland University of Technology, AUT N Shore Campus, AA254, 90 Akoranga Dr, Northcote 0627, Private Bag 92006, Auckland 1142, New Zealand. E-mail


Background and Purpose—Although the research linking cardiovascular disorders to geomagnetic activity is accumulating, robust evidence for the impact of geomagnetic activity on stroke occurrence is limited and controversial.
Methods—We used a time-stratified case-crossover study design to analyze individual participant and daily geomagnetic activity (as measured by Ap Index) data from several large population-based stroke incidence studies (with information on 11 453 patients with stroke collected during 16 031 764 person-years of observation) in New Zealand, Australia, United Kingdom, France, and Sweden conducted between 1981 and 2004. Hazard ratios and corresponding 95% confidence intervals (CIs) were calculated.
Results—Overall, geomagnetic storms (Ap Index 60+) were associated with 19% increase in the risk of stroke occurrence (95% CI, 11%–27%). The triggering effect of geomagnetic storms was most evident across the combined group of all strokes in those aged <65 by="" increasing="" risk="" stroke="" years="">50%: moderate geomagnetic storms (60–99 Ap Index) were associated with a 27% (95% CI, 8%–48%) increased risk of stroke occurrence, strong geomagnetic storms (100–149 Ap Index) with a 52% (95% CI, 19%–92%) increased risk, and severe/extreme geomagnetic storms (Ap Index 150+) with a 52% (95% CI, 19%–94%) increased risk (test for trend,P<2 style="border: 0px; font-style: inherit; line-height: 0; margin: 0px; outline-style: none; padding: 0px; position: relative; text-align: inherit; top: -2px; word-wrap: break-word;" sup="">−16
Conclusions—Geomagnetic storms are associated with increased risk of stroke and should be considered along with other established risk factors. Our findings provide a framework to advance stroke prevention through future investigation of the contribution of geomagnetic factors to the risk of stroke occurrence and pathogenesis.
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  • Received December 18, 2013.
  • Revision received March 10, 2014.
  • Accepted March 18, 2014.

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