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To the Editor We read with interest “Risk of Concussion for Athletes in Contact Sports at Higher Altitude vs at Sea Level: A Meta-analysis.”1 Unfortunately, Zavorsky and Smogila1 made errors that invalidate their meta-analysis. The authors mistakenly used altitude (in feet) as the number of adverse events.2 Detailed in Table 11 were 842 concussions used for the low altitude group and 52 concussions used for the high altitude group (which were actually median altitudes in feet, not incident concussions) taken from the original report that only had 284 total concussions.2 The authors also excluded relevant concussion data from Lynall et al,3 ignoring the incident concussions between 178 m and 284 m, thus inaccurately increasing the relative effect size3 compared with the 2 larger studies included in their analysis.2,4
Myer GD, Schneider DK, Khoury J. Correct Data and Meta-analytic Approaches Show the Reduced Risk of Concussion for Athletes Playing at Higher Altitudes. JAMA Neurol. 2017;74(4):484–485. doi:10.1001/jamaneurol.2016.6065
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