Interaction of Surface Type, Temperature, and Week of Season on Concussion Risk in the National Football League: A Bayesian Analysis.

BACKGROUND: Artificial turf fields and environmental conditions may influence sports concussion risk, but existing research is limited by uncontrolled confounding factors, limited sample size, and the assumption that risk factors are independent of one another. The purpose of this study was to examine how playing surface, time of season, and game temperature relate to diagnosed concussion risk in the National Football League (NFL). METHODS: This retrospective cohort study examined data from the 2012 to the 2019 NFL regular season. We fit Bayesian negative binomial regression models to relate how playing surface, game temperature, and week of the season independently related to diagnosed concussion risk and any interactions among these factors. RESULTS: We identified 1096 diagnosed concussions in 1830 games. There was a >99% probability that concussion risk was reduced on grass surface (median incidence rate ratio [IRR] = 0.78 [95% credible interval: 0.68, 0.89]), >99% probability that concussion risk was lower at higher temperatures (IRR = 0.85 [0.76,0.95] for each 7.9 °C), and >91% probability that concussion risk increased with each week of the season (IRR = 1.02 [1.00,1.04]). There was an >84% probability for a surface × temperature interaction (IRR = 1.01 [0.96, 1.28]) and >75% probability for a surface × week interaction (IRR = 1.02 [0.99, 1.05]). CONCLUSIONS: Diagnosed concussion risk is increased on artificial turf compared with natural grass, and this is exacerbated in cold weather and, independently, later in the season. The complex interplay between these factors necessitates accounting for multiple factors and their interactions when investigating sports injury risk factors and devising mitigation methods.

Hemoglobin Levels Among Male Agricultural Workers: Analyses From the Demographic and Health Surveys to Investigate a Marker for Chronic Kidney Disease of Uncertain Etiology.

OBJECTIVE: Estimate agricultural work's effect on hemoglobin (Hgb) level in men. A negative effect may indicate presence of chronic kidney disease of uncertain etiology. METHODS: We use Demographic and Health Surveys data from seven African and Asian countries and use matching to control for seven confounders. RESULTS: On average, Hgb levels were 0.09 g/dL lower among agricultural workers compared with matched controls. Significant effects were observed in Ethiopia, India, Lesotho, and Senegal, with effects from 0.07 to 0.30 g/dL lower Hgb level among agricultural workers. The findings were robust to multiple control groups and a modest amount of unmeasured confounding. CONCLUSIONS: Men engaged in agricultural work in four of the seven countries studied have modestly lower Hgb levels. Our data support integrating kidney function assessments within Demographic and Health Surveys and other population-based surveys.

Participation in Collision Sports and Cognitive Aging Among Swedish Twins.

We examined the association between early-life participation in collision sports and later-life cognitive health over a 28-year period in a population-based sample drawn from the longitudinal Swedish Adoption/Twin Study of Aging (1987-2014). Cognitive measures included the Mini-Mental State Examination and performance across multiple cognitive domains (e.g., global cognition, verbal ability, spatial ability, memory, processing speed). Among a sample of 660 adults (mean age at baseline, 62.8 years (range: 50-88); 58.2% female), who contributed 10,944 person-years of follow-up, there were 450 cases of cognitive impairment (crude rate = 41.1/1,000 person-years). Early-life participation in collision sports was not significantly associated with cognitive impairment at baseline or with its onset over a 28-year period in a time-to-event analysis, which accounted for the semi-competing risk of death. Furthermore, growth curve models revealed no association between early-life participation in collision sports and the level of or change in trajectories of cognition across multiple domains overall or in sex-stratified models. We discuss the long-term implications of adolescent participation in collision sports on cognitive health.

The association between adolescent football participation and early adulthood depression.

Concerned about potentially increased risk of neurodegenerative disease, several health professionals and policy makers have proposed limiting or banning youth participation in American-style tackle football. Given the large affected population (over 1 million boys play high school football annually), careful estimation of the long-term health effects of playing football is necessary for developing effective public health policy. Unfortunately, existing attempts to estimate these effects tend not to generalize to current participants because they either studied a much older cohort or, more seriously, failed to account for potential confounding. We leverage data from a nationally representative cohort of American men who were in grades 7-12 in the 1994-95 school year to estimate the effect of playing football in adolescent on depression in early adulthood. We control for several potential confounders related to subjects' health, behavior, educational experience, family background, and family health history through matching and regression adjustment. We found no evidence of even a small harmful effect of football participation on scores on a version of the Center for Epidemiological Studies Depression scale (CES-D) nor did we find evidence of adverse associations with several secondary outcomes including anxiety disorder diagnosis or alcohol dependence in early adulthood. For men who were in grades 7-12 in the 1994-95 school year, participating or intending to participate in school football does not appear to be a major risk factor for early adulthood depression.

Observational Study of the Associations of Participation in High School Football With Self-Rated Health, Obesity, and Pain in Adulthood.

American football is the most popular high school sport in the United States, yet its association with health in adulthood has not been widely studied. We investigated the association between high school football and self-rated health, obesity, and pain in adulthood in a retrospective cohort study of data from the Wisconsin Longitudinal Study (1957-2004). We matched 925 males who played varsity football in high school with 1,521 males who did not play football. After matching, playing football was not associated with poor or fair self-rated health (odds ratio (OR) = 0.88, 95% confidence interval (CI): 0.63, 1.24; P = 0.48) or pain that limited activities (OR = 0.86, 95% CI: 0.59, 1.25; P = 0.42) at age 65 years. Football was associated with obesity (body mass index (weight (kg)height (m)2) ≥30) in adulthood (OR = 1.32, 95% CI: 1.06, 1.64; P = 0.01). The findings suggest that playing football in high school was not significantly associated with poor or fair self-related health at age 65 years, but it was associated with the risk of being obese as an adult in comparison with not playing football in high school. Our findings provide needed information about the risk of playing football with regard to a broader set of health outcomes.

Association of Playing High School Football With Cognition and Mental Health Later in Life.

Importance: American football is the largest participation sport in US high schools and is a leading cause of concussion among adolescents. Little is known about the long-term cognitive and mental health consequences of exposure to football-related head trauma at the high school level. Objective: To estimate the association of playing high school football with cognitive impairment and depression at 65 years of age. Design, Setting, and Participants: A representative sample of male high school students who graduated from high school in Wisconsin in 1957 was studied. In this cohort study using data from the Wisconsin Longitudinal Study, football players were matched between March 1 and July 1, 2017, with controls along several baseline covariates such as adolescent IQ, family background, and educational level. For robustness, 3 versions of the control condition were considered: all controls, those who played a noncollision sport, and those who did not play any sport. Exposures: Athletic participation in high school football. Main Outcomes and Measures: A composite cognition measure of verbal fluency and memory and attention constructed from results of cognitive assessments administered at 65 years of age. A modified Center for Epidemiological Studies' Depression Scale score was used to measure depression. Secondary outcomes include results of individual cognitive tests, anger, anxiety, hostility, and heavy use of alcohol. Results: Among the 3904 men (mean [SD] age, 64.4 [0.8] years at time of primary outcome measurement) in the study, after matching and model-based covariate adjustment, compared with each control condition, there was no statistically significant harmful association of playing football with a reduced composite cognition score (-0.04 reduction in cognition vs all controls; 97.5% CI, -0.14 to 0.05) or an increased modified Center for Epidemiological Studies' Depression Scale depression score (-1.75 reduction vs all controls; 97.5% CI, -3.24 to -0.26). After adjustment for multiple testing, playing football did not have a significant adverse association with any of the secondary outcomes, such as the likelihood of heavy alcohol use at 65 years of age (odds ratio, 0.68; 95% CI, 0.32-1.43). Conclusions and Relevance: Cognitive and depression outcomes later in life were found to be similar for high school football players and their nonplaying counterparts from mid-1950s in Wisconsin. The risks of playing football today might be different than in the 1950s, but for current athletes, this study provides information on the risk of playing sports today that have a similar risk of head trauma as high school football played in the 1950s.