Department of Public Health, Syracuse University, Syracuse, New York.
Department of Sport Analytics, Syracuse University, Syracuse, New York.
JAMA Netw Open. 2020 May 1;3(5):e204442. doi: 10.1001/jamanetworkopen.2020.4442.
Long-term adverse health outcomes, particularly those associated with repetitive head impacts, are of growing concern among US-style football players in the US and Canada.
To assess whether exposure to repetitive head impacts during a professional football career is associated with an increase in the risk of all-cause mortality.
DESIGN, SETTING, AND PARTICIPANTS: This retrospective cohort study included 13 912 players in the 1969 to 2017 National Football League (NFL) seasons. All cause-mortality up until July 1, 2018, was included. Data collection was performed from July 13, 2017, to July 1, 2018, as reported in the Pro Football Reference.
The main exposure was a professional football cumulative head impact index (pfCHII). The pfCHII was measured by combining cumulative padded practice time and games played summed during seasons of play reported in the Pro Football Reference and a player position risk adjustment from helmet accelerometer studies.
Demographic characteristics except for the pfCHII were calculated for 14 366 players with complete follow-up. The pfCHII was calculated for 13 912 players (eliminating the 454 specials teams players). Cox proportional hazards regression was used to compare hazard ratios (HRs) of death by repetitive head impacts. Analyses were unadjusted and adjusted for birth year, body mass index, and height.
Among 14 366 NFL players who had follow-up for analysis, the mean (SD) age was 47.3 (14.8) years, the mean (SD) body mass index was 29.6 (3.9), and 763 of 14 366 players (5.3%) had died. Among 13 912 players in the pfCHII analysis, the median pfCHII was 32.63 (interquartile range, 13.71-66.12). A 1-log increase in pfCHII was significantly associated with an increased hazard of death for the 1969 to 2017 seasons (HR, 2.02; 95% CI, 1.21-3.37; P = .01) after adjustment. The quadratic pfCHII was also statistically significant (HR, 0.91; 95% CI, 0.85-0.98; P = .01), indicating that the hazard of death increased at a decreasing rate, whereas the pfCHII increased.
The findings suggest that an increase in repetitive head impacts is associated with an increased hazard of death among NFL players. Reduction in repetitive head impacts from playing football or other activities through additional rule and equipment changes may be associated with reduced mortality.
长期不良健康后果，尤其是与反复头部撞击相关的后果，是美国和加拿大美式足球运动员日益关注的问题。
评估在职业足球生涯中反复头部撞击的暴露是否与全因死亡率的增加相关。
设计、地点和参与者：本回顾性队列研究纳入了 1969 年至 2017 年美国国家橄榄球联盟（NFL）赛季的 13912 名球员。包括截至 2018 年 7 月 1 日的所有原因死亡。数据采集于 2017 年 7 月 13 日至 2018 年 7 月 1 日进行，如 Pro Football Reference 所报告的那样。
主要暴露因素是职业足球累积头部撞击指数（pfCHII）。pfCHII 通过结合在 Pro Football Reference 中报告的赛季中累积的软垫练习时间和比赛次数，以及头盔加速度计研究中的球员位置风险调整来测量。
除了 pfCHII 之外，14366 名具有完整随访的球员的人口统计学特征都进行了计算。13912 名球员（剔除了 454 名特别队球员）计算了 pfCHII。使用 Cox 比例风险回归比较因反复头部撞击而导致的死亡风险比（HR）。分析未调整和调整了出生年份、体重指数和身高。
在有分析随访的 14366 名 NFL 球员中，平均（SD）年龄为 47.3（14.8）岁，平均（SD）体重指数为 29.6（3.9），14366 名球员中有 763 名（5.3%）死亡。在 pfCHII 分析的 13912 名球员中，pfCHII 的中位数为 32.63（四分位间距，13.71-66.12）。在 1969 年至 2017 赛季，pfCHII 每增加 1 个对数单位，死亡风险显著增加（HR，2.02；95%CI，1.21-3.37；P=0.01），经调整后仍具有统计学意义。二次 pfCHII 也具有统计学意义（HR，0.91；95%CI，0.85-0.98；P=0.01），表明死亡风险的增加率呈下降趋势，而 pfCHII 则呈上升趋势。
研究结果表明，在 NFL 球员中，反复头部撞击的增加与死亡风险的增加相关。通过增加规则和设备的改变来减少足球或其他活动中的反复头部撞击，可能与死亡率的降低相关。
