# Mortality and chronic traumatic encephalopathy (CTE) among enforcers and non-enforcers in the National Hockey League (NHL)

## TL;DR

NHL enforcers, who often fight, face higher mortality and more CTE diagnoses compared to non-enforcers, highlighting risks from repeated head impacts.

## Contribution

This study provides empirical evidence linking enforcer roles in hockey to increased mortality and CTE diagnoses.

## Key findings

- Enforcers had a significantly higher mortality rate (9.6%) compared to non-enforcers (3.8%).
- Enforcers were more likely to be diagnosed with CTE (2.9%) than non-enforcers (0.4%).
- Enforcers who died were on average 9+ years younger than non-enforcers who died.

## Abstract

Many NHL teams roster players whose primary responsibility is fighting with opposing players. Over time, these “enforcers” may experience repetitive head impacts (RHI), a risk factor for serious long-term health consequences including neurodegenerative disease. This study examined whether retired NHL enforcers and non-enforcers differ on two long-term health outcomes.

In this matched cohort study conducted with retrospective, publicly available data, cohorts of former NHL enforcers and non-enforcers were compared on mortality, and CTE diagnosis. NHL players were deemed enforcers (ENFs, n = 239) if listed in a Wikipedia piece entitled “List of NHL enforcers.” A randomly selected sample of non-enforcers (non-ENFs, n = 239) were matched to ENFs on year of birth and the first NHL season played. Goalies and players with less than 30 games of NHL experience were excluded.

The matching procedure resulted in equivalent cohorts with respect to birth year (1969.9) and first NHL season played (1991.3). Significantly more ENFs had died (n = 23, 9.6% vs. n = 9, 3.8%; p = 0.01) and significantly more ENFs had been given a diagnosis of CTE (n = 7, 2.9% vs. n = 1, 0.4%; p < 0.05). While not statistically significant, age at death averaged 9+ years younger among ENFs (mean = 53.6) compared to non-ENFs (mean = 63). Players born in Canada were over-represented in the ENF cohort.

This study found higher mortality and more diagnoses of CTE in a cohort of enforcers relative to matched non-enforcers. Given expanding evidence linking RHI to life-threatening long-term health impacts, the NHL must protect players and mandate rule changes that minimize or eliminate fighting.