An Analysis of Guardian Cap Use and Changes in the Concussion Rate in National Football League Preseason Practices From 2018 to 2023.

Background: Laboratory testing has shown that the Guardian Cap NXT, an aftermarket padded football helmet cover, reduces head acceleration in test dummies compared with a helmet alone. However, it is unknown whether use of the Guardian Cap NXT is associated with a reduction in concussions on the field.

Purpose: To study the effect of Guardian Cap NXT use on the incidence of concussions in National Football League (NFL) preseason practices from 2018 to 2023.

Study Design: Cohort study; Level of evidence, 3.

Methods: Using data from the NFL Injury Surveillance System, concussion rates in preseason practices during the 2018 to 2023 preseasons (excluding the 2020 preseason) were compared before and after the NFL required players in certain positions (offensive linemen, defensive linemen, tight ends, and linebackers) to wear the Guardian Cap NXT during practices in 2022. Several secondary analyses, including 2 Poisson regression models, were conducted to evaluate the effects of preseason, player position, practice intensity (pads vs no pads), collision partner, helmet shell involvement, and Guardian Cap NXT requirement.

Results: A total of 139 concussions occurred during the preseason Guardian Cap NXT requirement period in 2018, 2019, 2021, 2022, and 2023. After the Guardian Cap NXT requirement was implemented, the concussion rate in the group of affected positions decreased 54% ( = .001) in the univariate analysis and 62% ( = .004) in the regression model. For concussions involving the helmet shell (as opposed to the facemask) (n = 76), there was no significant association between Guardian Cap NXT use and the concussion rate ( = .122), indicating that the reduction in concussions could not be attributed solely to the energy-absorbing effects of the Guardian Cap NXT.

Conclusion: Required use of the Guardian Cap NXT was associated with a 54% to 62% reduction in the overall incidence of NFL practice concussions. However, when only concussions involving a helmet shell impact were considered, there was no longer a significant relationship between Guardian Cap NXT use and the incidence of concussions.