Table 3.
Associations of exposure to individual sports with occurrence of combined CTE pathology and CTE‐positive in males. Abbreviations: CTE = chronic traumatic encephalopathy; OR = odds ratio; CI = confidence interval.
| Sport | N | Association with combined CTE pathology | Association with CTE‐positive | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| N (%) with combined CTE | Unadjusted analysis | Adjusting for age at death, baseball, boxing and football† | N (%) with CTE‐positive | Unadjusted analysis | Adjusting for boxing and football‡ | ||||||
| OR (95% CI) | P‐value | OR (95% CI) | P‐value | OR (95% CI) | P‐value | OR (95% CI) | P‐value | ||||
| Primary analysis of individual sports | |||||||||||
| Baseball | |||||||||||
| No | 413 | 32 (7.8%) | 1.00 (reference) | N/A | 1.00 (reference) | N/A | 16 (3.9%) | 1.00 (reference) | N/A | 1.00 (reference) | N/A |
| Yes | 64 | 9 (14.1%) | 1.95 (0.88, 4.30) | 0.099 | 1.42 (0.62, 3.27) | 0.41 | 5 (7.8%) | 2.10 (0.74, 5.95) | 0.16 | 1.57 (0.52, 4.72) | 0.43 |
| Basketball | |||||||||||
| No | 385 | 30 (7.8%) | 1.00 (reference) | N/A | 1.00 (reference) | N/A | 16 (4.2%) | 1.00 (reference) | N/A | 1.00 (reference) | N/A |
| Yes | 92 | 11 (12.0%) | 1.61 (0.77, 3.34) | 0.20 | 0.95 (0.41, 2.23) | 0.91 | 5 (5.4%) | 1.33 (0.47, 3.72) | 0.59 | 0.97 (0.32, 2.95) | 0.95 |
| Boxing | |||||||||||
| No | 470 | 39 (8.3%) | 1.00 (reference) | N/A | 1.00 (reference) | N/A | 19 (4.0%) | 1.00 (reference) | N/A | 1.00 (reference) | N/A |
| Yes | 7 | 2 (28.6%) | 4.42 (0.83, 23.54) | 0.081 | 3.62 (0.63, 20.79) | 0.15 | 2 (28.6%) | 9.50 (1.73, 52.12) | 0.010 | 10.29 (1.79, 59.28) | 0.009 |
| Football | |||||||||||
| No | 337 | 20 (5.9%) | 1.00 (reference) | N/A | 1.00 (reference) | N/A | 10 (3.0%) | 1.00 (reference) | N/A | 1.00 (reference) | N/A |
| Yes | 140 | 21 (15.0%) | 2.80 (1.46, 5.35) | 0.002 | 2.62 (1.33, 5.15) | 0.005 | 11 (7.9%) | 2.79 (1.16, 6.73) | 0.022 | 2.87 (1.17, 7.01) | 0.021 |
| Hockey | |||||||||||
| No | 457 | 39 (8.5%) | 1.00 (reference) | N/A | 1.00 (reference) | N/A | 20 (4.4%) | 1.00 (reference) | N/A | 1.00 (reference) | N/A |
| Yes | 20 | 2 (10.0%) | 1.19 (0.27, 5.32) | 0.82 | 1.27 (0.27, 5.97) | 0.77 | 1 (5.0%) | 1.15 (0.15, 9.03) | 0.89 | 1.44 (0.18, 11.53) | 0.73 |
| Soccer§ | |||||||||||
| No | 472 | 41 (8.7%) | 1.00 (reference) | N/A | N/A | N/A | 21 (4.5%) | 1.00 (reference) | N/A | N/A | N/A |
| Yes | 5 | 0 (0.0%) | N/A | 1.00 | N/A | N/A | 0 (0.0%) | N/A | 1.00 | N/A | N/A |
| Wrestling | |||||||||||
| No | 438 | 38 (8.7%) | 1.00 (reference) | N/A | 1.00 (reference) | N/A | 20 (4.6%) | 1.00 (reference) | N/A | 1.00 (reference) | N/A |
| Yes | 39 | 3 (7.7%) | 0.88 (0.26, 2.98) | 0.83 | 0.86 (0.25, 3.05) | 0.82 | 1 (2.6%) | 0.55 (0.07, 4.21) | 0.56 | 0.43 (0.06, 3.38) | 0.42 |
| Other† | |||||||||||
| No | 473 | 41 (8.7%) | 1.00 (reference) | N/A | N/A | N/A | 21 (4.4%) | 1.00 (reference) | N/A | N/A | N/A |
| Yes | 4 | 0 (0.0%) | N/A | 1.00 | N/A | N/A | 0 (0.0%) | N/A | 1.00 | N/A | N/A |
| Subgroup analysis ¶ | |||||||||||
| Baseball—youth or high school only | |||||||||||
| No | 413 | 32 (7.8%) | 1.00 (reference) | N/A | 1.00 (reference) | N/A | 16 (3.9%) | 1.00 (reference) | N/A | 1.00 (reference) | N/A |
| Yes | 48 | 6 (12.5%) | 1.70 (0.67, 4.30) | 0.26 | 1.11 (0.41, 3.00) | 0.83 | 5 (10.4%) | 2.89 (1.01, 8.26) | 0.048 | 2.03 (0.66, 6.32) | 0.22 |
| Baseball—beyond high school ¶ | |||||||||||
| No | 461 | 38 (8.2%) | 1.00 (reference) | N/A | 1.00 (reference) | N/A | 21 (4.6%) | 1.00 (reference) | N/A | N/A | N/A |
| Yes | 12 | 3 (25.0%) | 3.71 (0.96, 14.29) | 0.057 | 3.89 (0.98, 15.44) | 0.053 | 0 (0.0%) | N/A | 1.00 | N/A | 1.00 |
| Football—youth/high school only | |||||||||||
| No | 337 | 20 (5.9%) | 1.00 (reference) | N/A | 1.00 (reference) | N/A | 10 (3.0%) | 1.00 (reference) | N/A | 1.00 (reference) | N/A |
| Yes | 124 | 14 (11.3%) | 2.02 (0.99, 4.13) | 0.055 | 1.84 (0.87, 3.90) | 0.11 | 8 (6.5%) | 2.26 (0.87, 5.85) | 0.095 | 2.29 (0.87, 6.03) | 0.094 |
| Football—beyond high school | |||||||||||
| No | 461 | 34 (7.4%) | 1.00 (reference) | N/A | 1.00 (reference) | N/A | 18 (3.9%) | 1.00 (reference) | N/A | 1.00 (reference) | N/A |
| Yes | 15 | 7 (46.7%) | 10.99 (3.76, 32.13) | <0.001 | 13.23 (4.23, 41.36) | <0.001 | 3 (20.0%) | 6.15 (1.60, 23.74) | 0.008 | 6.84 (1.76, 26.66) | 0.0056 |
ORs, 95% CIs and P‐values result from logistic regression models. P‐values < 0.00625 were considered as statistically significant after applying a Bonferroni adjustment for multiple testing. Information was unavailable regarding level of baseball played (N = 4) and level of football played (N = 1).
Models involving baseball—youth or high school and baseball—beyond high school were not adjusted for baseball, and models adjusting for football—youth or high school and football—beyond high school were not adjusted for football.
Models involving football—youth or high school and football—beyond high school were not adjusted for football.
Because of the lack of subjects who played soccer or other sports and who had combined CTE pathology or CTE‐positive, logistic regression analysis was not possible; P‐values result from Fisher's exact test and multivariable analysis was not performed.
Only baseball and football were examined in subgroup analysis as these were the only sports for which a reasonable number of subjects played beyond high school. When comparing individuals who did and did not play a given youth or high school sport, individuals who played that sport beyond high school were excluded to avoid combining individuals who did not play a given sport and individuals who played that sport beyond high school in to the same category.
Because of the lack of subjects who played baseball beyond high school and who had CTE‐positive, logistic regression analysis was not possible; P‐values result from Fisher's exact test and multivariable analysis was not performed.