Incidence, proportion of concussion decreased after NHL rule implementation

Key takeaways:

• Incidence and proportion of concussions for NHL players before and after Rule 48 were analyzed.
• The researchers wrote that the findings indicate a change in player behavior leading to concussions.

A decrease of incidence and proportion of concussions resulted from implementation of a rule in the National Hockey League forbidding hits to the head, researchers reported in JAMA Network Open.

“Identifying appropriate policy or rule changes to potentially reduce the risk of concussion appears to differ by sport,” Michael G. Hutchison, PhD, an associate professor of sport concussion in the department of kinesiology and physical education at the University of Toronto, and colleagues wrote. “Ice hockey is a collision sport played within a confined space, often at high velocities and with rapid direction changes.”

As a rule prohibiting direct hits to the lateral side of the head (Rule 48) was introduced in the NHL in the 2010 to 2011 season and refined the following year to include direct contact to all areas of the head, Hutchison and colleagues sought to compare incidence and proportion of concussions following hits to the head before and after the implementation of that policy.

Their retrospective cohort study employed a before and after design to evaluate the incidence and proportion of concussions sustained by NHL players during regular-season competition, diagnosed by team physicians consistent with criteria established by the Concussion in Sport Group across two specific intervals. Data from seasons preceding the implementation of Rule 48 (2006-2007 to 2009-2010; n = 231) were compared with data from 5 seasons after its implementation (2014-2015 to 2018-2019; n = 457).

Multiple methods were utilized to analyze concussion data, and analysis was completed between Oct. 31, 2021, and Nov. 30, 2022.

Researchers observed an overall increase in the incidence of concussion between each time frame (2006-2007 to 2009-2010, n = 301/4,920 games; 2014-2015 to 2018-2019, n = 516/6,232 games).

However, results showed incidence of concussions due to hits to the lateral aspect of the head decreased from 1.6 per 100 games to 1 per 100 games (estimated difference,0.6/100 games [90% credible interval (CrI),0.3/100 games to 0.9/100 games), with a reduction of 18.8 (90% CrI,13-23.7) percentage points in the proportion of concussions due to hits to the lateral aspect of the head from 80 of 231 concussions (34.6%) to 61 of 457 concussions (13.3%).

Data further demonstrated incidence of concussions following hits to the head from body checks using the shoulder, arm and glove was similar before and after the implementation of Rule 48. Conversely, the proportion was reduced 14.7 percentage points from 113 of 231 concussions (48.9%) before Rule 48 to 149 of 457 concussions (32.6%) after implementation (90% CrI of the difference,8.9-20.7 percentage points).

“Collectively, these findings further indicate that the introduction of Rule 48 has coincided with a change in player behavior leading to concussions,” Hutchison and colleagues wrote. “Continued efforts to identify meaningful primary prevention are still required.”