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Research Letter |

Risk of Concussion for Athletes in Contact Sports at Higher Altitude vs at Sea Level A Meta-analysis ONLINE FIRST

Gerald S. Zavorsky, PhD1; James M. Smoliga, DVM, PhD2,3
[+] Author Affiliations
1Department of Respiratory Therapy, Georgia State University, Atlanta
2Department of Physical Therapy, High Point University, High Point, North Carolina
3Department of Basic Pharmaceutical Sciences, High Point University, High Point, North Carolina
JAMA Neurol. Published online September 06, 2016. doi:10.1001/jamaneurol.2016.0795
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This meta-analysis examines the literature on concussion rates for athletes in contact sports at sea level and at a higher altitude.

It has been postulated that a higher altitude increases cerebral blood flow, which causes venous blood engorgement, increases intracranial pressure, and creates subsequent slight brain swelling and a tighter fit between the brain and the skull to decrease brain sloshing and reduce concussive events.1,2 The prospect of protecting the brain from within seems novel and exciting, but the proposed physiologic basis for this mechanism is not scientifically sound.3 Recent studies show conflicting data on whether the incidence of sports-related concussions are associated with altitude.1,2,4,5 Thus, we sought to determine whether the incidence of concussions from contact sports is different when the sport is played at sea level vs at a higher altitude.

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Forest Plot of Relative Risk for Concussions for Athletes Playing Contact Sports at Altitude (200 m to 300 m) vs at Sea Level (≤195 m)

A relative risk greater than 1 represented a higher risk of concussions at altitude compared with sea level. We used a random effects model because there was heterogeneity between studies (Cochran Q, 85.6; df, 2; I2, 97.7%; P < .001). Thus, the percentage weight was approximately 33% for each study. Publication bias is unlikely (funnel plot not shown). Error bars indicate 95% CIs for the relative risk.

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