Ivy League Football Concussions Drop With New Kickoff Rule

Damian McNamara

October 10, 2018

Moving the kickoff line in Ivy League football from the 35-yard to the 40-yard line in 2016 resulted in a precipitous drop in the concussion rate among players, researchers report.

A new study shows that the mean annual concussion rate per 1000 kickoff plays in the years before the experimental rule change was 10.93. Afterward, the rate dropped to 2.04.

"The take-home message is, a small but deliberate rule change seems to have substantially changed a feature of how football kickoffs are played and led to a dramatic reduction in the rate of concussions," lead author Douglas J. Wiebe, PhD, Department of Biostatistics, Epidemiology, and Informatics at the Perelman School of Medicine, University of Pennsylvania, Philadelphia, told Medscape Medical News.

The findings were published online October 1 in JAMA.

Hitting the Brakes on High-Speed Impacts

During kickoff returns, football players run quickly toward each other over a long distance. This disproportionately raises the potential for significant impacts compared with other plays, the researchers note.

For example, kickoffs accounted for 6% of all plays but were associated with 21% of concussions in 2015, according to a study of eight Ivy League Conference Division I universities in the National Collegiate Athletic Association (NCAA).

Armed with results like these and their own observations, Ivy League football coaches recommended the rule change. In addition to the kickoff line change, they suggested moving the touchback line from the 25-yard to the 20-yard line.

Ivy League football teams participate in the league's concussion surveillance system. Typically, athletic trainers identify players suspected of having concussion and refer them to a team physician for evaluation. Concussion diagnoses are entered into a Web-based repository.

Using this data source, Wiebe and colleagues quantified concussions from regular, in-season games during the five seasons from 2013 to 2017. They noted whether each concussion occurred during a kickoff or other play.

They also compared annual concussion rates before (2013-2015) and after (2016-2017) the rule change using a difference-in-differences approach. Annual concussion counts were modeled by year and play type, with play counts as exposures, using maximum likelihood Poisson regression to estimate rate differences, difference-in-differences, and 95% confidence intervals (CIs).

Key Stats

A total of 159 concussions occurred during 68,479 plays from 2013 through 2017. There were 126 concussions before the rule and 33 after.

According to a difference-in-differences analysis, there were 7.51 (95% CI, -12.88 to -2.14) fewer concussions for every 1000 kickoff plays after the rule change compared with the period before.

"We were surprised...by the magnitude of the effect. It was such a large reduction," Wiebe said.

One of the anticipated effects of moving the kickoff line closer to the opposing team's end zone was an increase in touchbacks. Instead of running at speed toward the other team, a player who catches the ball from a kickoff in the end zone can kneel and the play is over.

Wiebe and colleagues report that kickoffs leading to touchbacks increased from a mean of 18% annually before the rule change to 48% after.

The researchers also evaluated concussions occurring during other types of plays. The concussion rate associated with nonkickoff plays was 2.56 before the rule change and 1.18 after (difference, -1.38; 95% CI, -3.68 to 0.92).

"Perfect Summation"

"Although these results may not generalize beyond the Ivy League, they may inform the NCAA as it considers adjusting the kickoff rules in football in all collegiate conferences," the researchers note. The National Football League made a similar change in 2011, moving the professional players' kickoff line from the 30-yard to 35-yard line.

"The action taken by Ivy League leadership based on epidemiologic evidence demonstrates how targeted policy changes can reduce sport-related concussion," the investigators write.

That sentence "sums it up perfectly," Razib Khaund MD, clinical assistant professor of medicine at Brown University, Providence, Rhode Island, told Medscape Medical News when asked to comment.

The study is "really interesting," Khaund said. "Granted, the kickoffs are a small percentage, but the incidence [of concussions] is so high that it warrants attention."

He added that the rule change makes sense because, although kickoffs cannot be eliminated altogether, you can attempt to make them safer.

"Here at Brown University, our practices are minimal contact," so the amount of time players are permitted to physically contact each other is limited. In contrast, "25 years ago, when I played, we rammed heads all day long," Khaund said.

Snowball Effect

Also asked to comment by Medscape Medical News, Peggy Flannigan, PhD, professor of nursing at Bradley University in Peoria, Illinois, said, "The data clearly demonstrate a drop in concussion rate in this large sample from the Ivy League Conference. It is surprising if other NCAA conferences have not yet followed suit in adopting these rules.

"These findings have the potential for a snowball effect leading to greater safety in football," she added. "Additional research on these injuries may result in more rule changes, better equipment, and, most of all, a trickle-down effect all the way to the secondary and even Junior Football League teams."

This study, if replicated with other conferences in the NCAA or the National Association of Intercollegiate Athletics, has the potential to demonstrate an overall decrease in concussions and perhaps other injuries as well, Flannigan said.

"By decreasing concussions, we may also find a decrease in long-range effects of traumatic brain injury in athletes that has been suspected as leading to mental illness, suicide, and other pathologies," she added.

The current analysis is one component of the larger Ivy League–Big 10 Epidemiology of Concussion study. "We're in a position to do much more," Wiebe said, including engaging in randomized and prospective research.

For example, some schools are distributing new Vicis helmets (Vicis Inc, Seattle), which were developed by engineers and neurosurgeons. There are not enough of these helmets for all players, which Wiebe sees as a research opportunity. Randomizing distribution of these new helmets to players could form the basis of a clinical trial to determine the difference they make.

Dr Wiebe was funded through a contract from the Ivy League. The Penn Injury Science Center, which is funded by a CDC Injury Control Research Center grant, also provided support. Dr Khaund reported no relevant financial relationships.

JAMA. Published online October 1, 2018. Full article

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