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. 2021 Jun 3;11(6):e044320. doi: 10.1136/bmjopen-2020-044320

Table 4.

Outcome data for concussion, head injury and injuries to other body regions stratified by HG versus no-HG

Study N No-HG exposures HG exposures No-HG
SRC
HG
SRC
No-HG superficial head injury HG superficial head injury No-HG all body regions combined HG all body regions combined
McIntosh and McCrory34 294 357 player game hours 1179 player game hours n=2
*Relative Risk=0.94
95% CI
(0.19 to 4.52)
n=7 n=7
*Relative risk=
1.54
90% CI
(0.63 to 3.75)
n=15
Marshall et al 200530 304 4656 player weeks 752 player weeks Not reported Rate ratio=1.13
95% CI
(0.40–3.16)
Not reported Rate ratio=0.59,
95% CI
(0.19 to 1.85)
Not reported Rate ratio=
0.96,
95% CI
(0.75 to 1.23)
Delaney et al 39 278 n=216 players n=52 players n=114
relative risk=2.65, 95% CI (1.23 to 3.12)
n=14 n=151
relative risk=1.86, 96% CI (1.49 to 3.45)
n=15
Hollis et al 33 3207 n=985
players
n=671 players 7.48 per 1000 player hours.
*Relative Risk=0.68 95% CI (0.24 to 1.93)
7.39 per 1000 player hours.
McIntosh et al 32 3686 1493 player game hours Standard HG 1,128 player game hours n=90 n=85 with standard HG.
Incidence Rate ratio=1.13, 95% CI
(0.86 to 1.49)
n=106 n=100 with standard HG.
Incidence Rate ratio=1.14,
95% CI
(0.84 to 1.54)
n=799 n=828 with standard
HG.
Incidence Rate ratio=
1.16, 95% CI
(1.04 to 1.29)
Modified HG
1474 player game hours
See above row for control group n=19 with Modified HG.
Incidence Rate ratio=1.06, 95% CI
(0.70 to 1.60)
See above row for control group n=22 with modified HG.
Incidence Rate ratio=1.03
95% CI
(0.67 to 1.58)
See above row for control group n=175 with modified HG.
Incidence Rate ratio=1.05
95% CI
(0.78 to 1.41)
Chalmers et al 29 704 4223 player game hours 1807
player game hours
n=4419 injuries. Incidence rate ratio:1.00 n=1844 injuries. incidence rate ratio: 1.26
95% CI
(1.00 to 1.50)
Archbold et al 21 811 n=553 players n=258 players n=42
*relative risk=0.63,
95% CI
(0.41 to 0.98)
n=31 log rank=0.327; df=1; p=0.567) Not reported n=549
*relative risk=0.99
95% CI
(0.99 to 1.00)
n=258
McGuine et al 31 3050 n=1545 players n=1505
players
n=68 n=62
risk ratio=0.98, 95% CI (0.62 to 1.56)
Not reported Risk ratio=
0.91, 95% CI
(0.64 to 1.29)

*Denotes crude relative risk as calculated by authorsof the review to facilitate consistency of interpretation. - Denotes missingdata as outcome not analysed in the study.

HG, headgear; SRC, sports related concussion.