Observational research has linked altitude to concussion risk, but the physiologic and epidemiologic bases for this association remain questionable.
We performed a retrospective cohort study by analyzing four seasons of National Football League data from a widely used database (Concussion Watch) to determine if previous claims that altitude ≥196 m reduced concussion risk were replicable and whether an arbitrary predictor variable (animal vs. non-animal team logo) was related to concussion risk. Relative risk (RR) and 95% confidence intervals (95% CIs) were computed.
The previous association with altitude was reproduced for earlier seasons, but not replicable for recent seasons (RR = 0.92 [95% CI = 0.70, 1.22]). Across four combined seasons, “higher altitude” (RR = 0.78 [0.64, 0.96]) and animal logo (RR = 0.75 [0.63, 0.89]) were similarly associated with reduced concussion risk.
Inconsistent epidemiologic effects, combined with weak physiologic rationale, suggest links between altitude and concussion are coincidental. Interdisciplinary critique of concussion research is necessary to ensure that marketing claims and clinical recommendations are scientifically justified.
See video abstract at, http://links.lww.com/EDE/B234.
Supplemental Digital Content is available in the text.
From the aDepartment of Physical Therapy, One University Parkway, High Point University, High Point, NC; and bDepartment of Respiratory Therapy, Georgia State University, Georgia State University, Atlanta, GA.
Submitted 26 July 2016; accepted 5 May 2017.
The authors report no conflicts of interest.
Data Availability: The full data set from this manuscript is available with this article as Dataset1. Data analysis was performed using a graphical user interface, thus no analysis code is available.
Supplemental digital content is available through direct URL citations in the HTML and PDF versions of this article (www.epidem.com).
Correspondence: James M. Smoliga, Department of Physical Therapy, One University Parkway, High Point University, High Point, NC 27268. E-mail: jsmoliga@highpoint.edu.
