Supplementary 2 Table 2: Characteristics of studies meeting inclusion criteria

Study

Sport (Country)

Study design (year, duration)

Participants (IG/CG: Sex; Level; Age; #teams(N), #players (n), number of concussions

Outcomes

Outcome definition

Intervention

Control

Incidence

Effect estimate (*significant protective effect, **adjusted estimate)

Downs and Black

Level of evidence

Protective Equipment: Helmets

Collins et al(24) 2016

Football (USA)

PC (2008-2013, 5 seasons)

M; High School;

IG1: 2900 concussions; IG2: 2552 concussions; IG3: 1967 concussions

Concussion

Medically identified – Proportion of concussed athletes with helmet characteristics vs. proportion of athletes with helmet characteristics

IG1. Helmet Age/Recondition status:

i. New; ii. Old/ Reconditioned; iii.Old /Not reconditioned

IG2: Helmet Manufacturer

i.Adams; ii.Rawlings; iii.Riddell; iv.Schutt;

v. Xenith

IG3: Helmet Model

i.Riddell Revolution; ii.Riddell Revolution Speed; iii.Schutt DNA; iv. Schutt Air; v.Schutt Air XP

Proportion of all athletes with helmet characteristics as reported by the helmet inventory survey

IG1: n (proportion)

i. 606 (20.9%)

ii. 1412 (48.8%)

iii. 126 (4.3%)

CG1: Not reported

IG2: n (proportion)

i. 35 (1.4%); ii. 9 (0.4%); iii. 1723 (67.5%); iv.725 (28.4%); v. 60 (2.4%)

CG2: n(proportion)

i.241 (1.0%); ii.0 (0%); iii.14510 (60.7%); iv.9116(38.1%); v.36(0.2%)

IG3:n(proportion)

i. 1376(63.4%); ii.142 (6.5%); iii.172 (7.9%); iv.126 (5.8%); v.151 (7.0%)

CG3:n(proportion)

i. 10698 (51.7%); ii. 1525 (7.4%); iii. 2200(10.6%); iv.1114 (5.4%); v.938 (4.5%)

 

1: No difference in mean number of concussion symptoms by age/recondition status (F=2.29; df=2; p=1.01)

2: iii. IPR=1.11 (1.08-1.15)

3: i. IPR=1.23 (1.19-1.27)

iii. *IPR = 0.75 (0.64-0.87)

 

9

2b

Collins et al (25)

(2006)

Football (USA)

PC (2002-2004, 3 seasons)

M; High School;

IG: n=1173,

CG: n=968

Concussion

Mechanism/ Specified Symptoms- Medically identified (AT/MD)

Riddell Revolution helmet (thicker padding over zygoma and mandible area)

Traditional Football helmet

IG:IP=5.3/100P; 3.7/100P** CG:IP=7.6/100P; 6.2/100P**

*RR(95%CI)=0.69 (0.50-0.96)

*RR(95%CI)=0.60 (0.40-0.88)**

17

2b

Greenhill et al(26)

(2016)

Football (USA)

HC (2005-2014, 9 years)

M; High school; age:13-19;

IG: n=3070,

CG: n=102

a. Concussion symptom reporting b. Average symptoms reported

c. Symptom duration longer than 1 week

Medically identified

Helmet fit recorded as appropriate based on AT

Helmet did not fit properly based on AT

3.22% suffered a concussion and had a helmet which did not fit properly

a. Drowsiness greater among non-fitting helmets: *RR:0.67 (p=0.0037)

b. Poor helmet fit averaged more symptoms: RR=5.34 vs. 4.54 (P=0.004)

c. Poor helmet fit: 37% vs. 30.8%, P=0.04

23

4

McGuine et al(27)

(2014)1

Football (USA)

PC (2012-2013, 2 seasons)

M; High School; ages:14-17

Concussion

AAN Guidelines- Medically identified

IG1. Helmet Type:

i. Riddell

ii. Xenith

iii. Schutt

IG2. Helmet Age:

i.1-2 years,

ii. 3-4 years,

iii. 5-6 years,

iv. 7+ years

Note: Reference groups:

1. Riddell

2.1-2 years

1i. IR=1.38 (1.03-1.86)
1ii. IR=1.73 (1.09-2.75)
1iiit: IR=1.57 (1.01-2.44)

2i.
IR=1.62 (1.19-2.22)
2.ii.: IR=1.25 (0.88-1.78)
2.iii: IR=1.51 (0.98-2.31)
2.iv: IR=1.82 (1.18-2.81)

1.Riddell: Reference

[OR(95%CI)]
Xenith: OR=1.00 (0.67-1.49)
Schutt: OR=0.94 (0.67-1.33)

2. 1-2yrs: Reference
3-4: OR=0.74 (0.51-1.06)
5-6: OR=0.78 (0.49-1.23)
7+: OR=0.97 (0.61-1.51)

19

2b

Rowson et al(28)

(2014)

Football (USA)

HC (2005-2010, 6 seasons)

M; Collegiate; N=8, n=1833

Concussion

Alteration in mental status resulting from a blow to the head- Player reported or medically identified

Riddell Revolution helmet (40% thicker foam and greater offset)

Riddell VSR4helmet

IG: 3.86 (2.78-5.34) concussion/100000 head impacts CG:IR=8.37(5.70-12.2) concussion/100000 head impacts

*RR(95%CI)=0.46 (0.28-0.75)

13

4

Marshall et al(29)

(2002)

Football and Rugby (USA & NZ)

EC (1993-1994, 1 season)

M; Collegiate

Concussion

Medically identified

Hard Shell Helmet & Protective equipment (Football)

No protective equipment (Rugby)

IG: IR=2.11 (1.63-2.59)/1000 player games
CG: IR=5.16 (2.24-8.08)/1000 player games

*IRR(95%CI)= 0.41 (0.22-0.75)

14

2c

Benson et al(30)

(2002)

Hockey (CAN)

PC (1997-1998, 1 season)

M; Collegiate; med age=22;

IG: N=11, n=319;

CG: N=11, n=323

Concussion

Medically identified

Full Face Shied

Half face Shield

IG: IR=1.57/1000AE CG:IR=1.53/1000AE

RR(95%CI)= 0.97 (0.61-1.57)

19

2b

Stuart et al(31) (2002)

Hockey (USA)

PC (us, us)

M; Junior A; ages 16-21;Total: N=12 teams, n=279

Concussion

Graded 1-3 based on LOC and timing of symptoms-Medically identified

IG1: Half Face Shield; IG2: Full Face Protection

No facial protection

IG1: IR=8.2 /1000hours IG2: IR=2.9 /1000hours CG: IR=12.2 /1000hours

IG1 vs. CG: IRR(95%CI)= 0.67 (0.14-3.36);

IG2 vs. CG: IRR(95%CI)= 0.24 (0.02-1.66)

19

2b

Hagel et al(32) (2005)

Ski & Snowboard (CAN)

CC (2001-2002, 1 season)

B; all ages; cases: n=1082, controls: n=3295

a. Head injury –including concussion or face or neck injury;

b. Severe head injury

a. Identified by ski patrol;

b. Ambulance transport required

Helmet use with Head or neck injury

Helmet use with non-head or neck injury

Frequency and proportion of head injury wearing a helmet:
175 (25.3%)

Frequency and proportion of head injury NOT wearing a helmet:
518 (74.8%)

a. *OR(95%CI)= 0.71 (0.55-0.92)

b. *OR(95%CI)= 0.44 (0.24-0.81)

24

3b

Protective Equipment: Headgear

Hollis et al(33) (2009)1

Rugby (AUS)

PC (2005-2007, 1-3 seasons)

M; Professional; Age: >=15; IG: n=1034, CG: us.

mTBI

At least 1 of: LOC ≤30 minutes, loss of memory, any alteration in mental state or if they left the field during a game due to dizziness, confusion, loss of coordination, and/or loss of consciousness; stoppage of play

Headgear use (self-report always wearing)

Never wearing protective headgear (self-report)

IG: 7.39 (5.55-9.65)
CG: 12.62 (8.38-18.27)

*IRR= 0.57(95%CI)= (0.40-0.82)

22

2b

Kemp et al(34) (2008)1

Rugby (ENG)

PC (2002-2004&2005-2006, 3 seasons)

M; Professional; 13 clubs, n-757

Concussion

2001 Consensus Statement- Medically identified

Headgear use

No Headgear use

IG: IR(95%CI)= 2.0 (1.0-4.2)/1000 hours

CG: IR(95%CI)=4.6 (3.7-7.7)/1000 hours

*IRR=0.43

17

4

McIntosh et al(35)

(2001)

Rugby (AUS)

RCT (us., 1 season)

M; Grade A team; age: <15; n=295; IG:N=9, CG:N=7

Concussion

Time loss injury definition- Diagnosis verified by medical

Headgear

No Headgear

IG: IR=5.94 (7/1179AE) CG:IR=5.60 (2/357)

IRR(95%CI)=1.06 (0.20-10.46)

13

1b

McIntosh et al(36)

(2009)

Rugby (AUS)

cRCT (us., 2 seasons)

M; ages 13-20;

Concussion

2001 Consensus Statement- Medically identified

IG1: Standard headgear
IG2: Modified headgear (thicker)

No Headgear

IG1:IR(95%CI)= 6.4
(4.9-8.4)/1000hours
IG2:IR(95%CI)= 7.5
(6.0-9.4)/1000hours
CG: IR(95%CI)=6.7
(5.2-8.5)/1000hours

IG2/ CG
IRR=0.954 (0.651-1.391)
IG2/ CG
IRR=1.126 (0.803-1.581)

24

1b

Marshall et al(37)

(2005)1

Rugby (NZ)

PC (1993, 1 season)

B; Competitive; n=304

Concussion

Medically identified

Headgear use

No Headgear use

us.

IRR(95%CI)=1.13 (0.40-3.16)

20

4

Achar et al(38) (2007)

Soccer (USA)

CS (2007, 1 season)

F; Collegiate; N=1; IG: n=4, CG: n=5

Concussion

us.

Headgear

No Headgear

IG: 1 concussion
CG:3 concussions

RR(95%CI)=0.42 (0.01-5.19)

10

4

Delaney et al(39)

(2008)

Soccer (CAN)

CS (2006, 1 season)

B; Recreational; ages;12-17; IG: n=53, CG: n=216

Concussion

Self-reported

Headgear

No Headgear

IG: IP= 26.9/100 players IC: IP= 52.8/100 players

*RR=0.38, p<0.0001

14

4

Protective Equipment: Mouthguards

Labella et al(40)

(2002)

Basketball (USA)

PC (1999-2000, 1 season)

M; Division I; Collegiate; 50 teams

Concussion

Medically identified

Custom fitted mouthguard

No Mouthguard

IG:IR= 0.35/1000AE CG:IR= 0.55/1000AE

RR(95%CI)=0.63 (0.12, 2.02)

10

4

Benson et al(41)

(2005)

Hockey (CAN)

PC (2003-2004, 1 season)

M; Professional; N=30, n=1014

Concussion

Medically identified

Mouthguard

No Mouthguard

IG: 39 concussions CG:33 concussions

OR(95%CI)=0.70 (0.44-1.11)

16

2b

Chisholm et al(42)

(2015)

Hockey (CAN)

nCC (2011-2012, 1 season)

B; All divisions; ages 11-17; cases: 143, controls: 156

Concussion

Medically identified

Mouthguard use with Concussion

Mouthguard use with MSK injury

us.

OR(95%CI)=0.81 (0.45-1.46)

17

3b

Momsen et al(43)

(2003)

Hockey (USA)

PC (2002-2003, 1 season)

M; Division 1; Collegiate; N=30 teams, n=1058

Concussion

Medically identified

IG1: Boil and Bite Mouthguard;

IG2: Custom Mouthguard

No Mouthguard

IG1:IR=1.36 per 1000 AE IG2:IR=1.28 per 1000AE CG:IR=1.07 per 1000AE

Est: IG1vsCG: RR(95%CI)= 1.27 (0.45-2.90)

 IG2vsCG: RR(95%CI)= 1.19 (0.71-1.94) IG1orIG2vsCG: RR(95%CI)= 1.21 (0.75-1.89)

14

2b

McGuine et al(27)

(2014)2

Football (USA)

PC (2012-2013, 2 season)

M; High School; ages 14-17

Concussion

AAN Guidelines- Medically identified

IG1: Custom mouthguard

IG2: Specialized mouthguard

CG: Generic mouthguard

IG1: IR=2.33 (1.49-3.66)
IG2: IR=1.70
(1.24-2.33)
CG: IR=1.29
(0.98-1.69)

Generic: Reference
Custom: OR=1.80 (1.09-2.87)
Specialized: OR=1.39
(1.00-1.92)

19

2b

Singh et al(44)

(2009)

Football (USA)

Pexp (us, 5 season)

M; High School; ages 15-20 IG and CG: n=28 (cross-over)

Concussion

Pre-intervention: Self report, Post-intervention: identified by coach and confirmed by physician

Customized mandibular orthotic worn over 3 seasons

No customized mandibular orthotic in 2 seasons prior to season

IG: 0.11 ± 0.3concussive events
 
CG: 2.1 ± 1.4 concussive events 

*OR=0.026 (95% CI; 0.0056-0.12)

8

4

Winters et al(45)

2014)

Football (USA)

RCT (2005, 1 season)

M; High School; ages 14-18;

IG: N=3, n=220; CG:N=3, n=192

Concussion

Traumatically induced alteration in mental status that results in post-injury cognitive and or symptom impairment.”- Medically Identified

Custom fitted mouthguard

Standard mouthguard

IG: IP= 3.6% (8/220)

CG: IP= 8.3% (16/192)

Est: RR=0.44 (0.19-1.00) Reported; *p=0.0423

11

2b

Wisniewski et al(46)

(2004)

Football (USA)

PC (2001, 1 season)

M; Division 1; Collegiate; N=87

Concussion

Medically identified

Custom fitted mouthguard

Standard mouthguard

IR/1000 AE:
Games
IG: IR=5.66
CG: IR=5.34
Contact practices
IG: IR=0.37
CG: IR=0.40
Non-contact practices
IG: IR=0.05
CG: IR=0.01

Games
IRR=1.061 (0.808-1.394)

Contact practices:
IRR=0.917 (0.599-1.402)

Non-contact practice
IRR= 5.917(0.627-55.877)

13

2b

Barbic et al(47)

(2005)

Football and Rugby (CAN)

RCT (2003, 1 season)

B; Collegiate;

IG:N=6, n=308, CG:N=6, n=306

Concussion

AAN Guidelines- Medically identified

WIPSS Brain-Pad mouthguard

Standard mouthguard

IG: IP= 7.14/100P
CG: IP= 6.85/100P

OR(95%CI)= 1.06 (0.51-1.61)

19

2b

Hollis et al(33)

(2009)2

Rugby (AUS)

PC (2005-2007, 1 -3 seasons)

M; Professional; Age: >=15; IG: n=1816, CG: us.

mTBI

At least 1 of: LOC ≤30 minutes, loss of memory, any alteration in mental state or if they left the field during a game due to dizziness, confusion, loss of coordination, and/or loss of consciousness; stoppage of play

Always wearing mouthguard (self-report)

Never wearing mouthguard (self-report)

IG: 7.45 (6.31-8.74)
CG: 13.36 (5.70-26.44)

IRR=0.56

22

2b

Kemp et al(34) (2008)2

Rugby (ENG)

PC (2002-2004&2005-2006, 3 seasons)

M; Professional; 13 clubs, n-757

Concussion

2001 Consensus Statement- Medically identified

Customized mouthguard

No mouthguard

IG: IR(95%CI)= 4.0 (3.2-5.0)/1000 hours CG:IR(95%CI)=5.88(3.6-9.3)/1000 hours

IRR=0.58

17

4

Marshall et al(37)

(2005)2

Rugby (NZ)

PC (1993, 1 season)

B; Competitive; n=304

Concussion

Medically identified

Mouthguard use

No mouthguard use

us.

IRR(95%CI)=1.13 (0.40-3.16)

20

4

Blignaut (48)

(1987)

Rugby (ZAF)

CS (us., us.)

M; First team; University; Ages: 18-29, n=321

Concussion

No specific concussion definition

Mouthguard use (questionnaire)

No Mouthguard

# Concussion:
IG: n=6, 3.1%
CG: n=9, 2.5%

Est: Concussion:
RR(95%CI) =0.81 (0.67-0.96)

6

4

Policy and Rule Changes

Bjørneboe et al(49)

(2013)

Soccer (NOR)

Pexp (2010-2011, 2 seasons)

M; Professional;

IG: n=240 games, CG: n=240

a. Opponent-to-player head and neck contact incident

b. Concussion (Number)

a. Video analysis: Any situation where the match was interrupted by the referee, the player stayed down for more than 15 sec and appeared to be pain or received medical treatment.

b. No specific concussion definition

2011 season post-rule change that involved stricter enforcement of red cards for high elbows in heading duels

2010 season pre-rule change

IG: a. 23.2 contacts /1000 player match hours (19.9 - 26.6)

b. 4 concussions

CG: a. 28.5 contacts /1000 player match hours (24.8 - 32.3

b. 3 concussions

a. *RR (95%CI)=0.81 (0.67-0.99)

10

4

Black et al(50)

(2016)

Hockey (CAN)

PC (2011-2012, 1 season)

M; non-elite; ages:11-12

IG: n= 281, N=46, CG: n=590, N=59

a. Concussion

b. Severe Concussion (>10 days time loss

2008 Consensus Statement- Medical referral

No Body Checking: League where policy change recently disallowed body checking (Ontario)

Body Checking: League where body checking is permitted (Alberta)

a. IG: IR(95%CI)= 0.91 (0.41-2.06) CG:IR(95%CI)= 2.78 (2.19-3.52)

b. IG:IR(95%CI)= 0.46 (0.15-1.42) CG:IR(95%CI)= 0.91 (0.58-1.42)

a.*IRR(95%CI): 0.35 (0.14-0.92)

b. IRR(95%CI):0.5 (0.15-1.67) 

24

2b

Cusimano et al(51)

(2011)

Hockey (CAN)

HC (1994-2004, 10 seasons)

M; ages 6-17

Concussion (Body-checking Related)

CHIRPP database definition

Policy Change allowing checking in Atom

Body Checking not allowed in Atom

# Body checking related concussions before and after rule change:
OR: 0.10 (0.02 – 0.43)

13

4

Donaldson et al(52)

(2013)

Hockey (CAN/USA)

CS (2009-2012, 3 seasons)

M;OHL/NHL; n=2211; IG:N=30, CG:N=20

Concussion

Suspected concussions were those described as concussion-like symptoms by the team or as concussions by multiple sports media sources (other than the team itself) and were injuries occurring as a result of trauma to the head.

NHL in the two seasons following implementation of Rule 48, allowing hits to the head

NHL in the season prior implementation of Rule 48


Secondary:
OHL where policy against checking to the head was present since 2006

Concussion Incidence per 100 games:
IG: 2010-2011: 5.28
2011-2012: 6.83
CG: 3.58
Concussion + Suspected Concussion incidence per 100 games:
IG: 2010-2011: 9.76
2011-2012: 10.24
CG: 6.26

IRRs estimated relative to 2010-2011 season.

*IRR= 0.64 (0.42-0.96)

Concussion + suspected concussion incidence per 100 games:
*IRR= 0.61 (0.45-0.83)

8

4

Black et al(53)

(2016)

Hockey (CAN)

HC (2011-2012/2013-2014, 2 seasons)

M; Pee Wee all divisions; age: 11-12; IG: N=73, n=618;

CG: N=59, n=883

a. Concussion

b. Severe Concussion (>10 days time loss

2012 Consensus Statement- Medical referral

2013-2014, policy disallowing body checking at the pee wee level

2011-2012, body checking allowed at the pee wee level

IG:IR 1.72/1000 game hours
CG:
Concussion IR
2.79/1000 game hours

*IRR:= 0.36(0.22-.58)

21

2b

Emery et al(54)

(2010)

Hockey (CAN)

PC (2007-2008, 1 season)

M; Pee Wee: top 60% divisions; age: 11-12; IG: N=74, n=1108; CG:N=76, n=1046

a. Concussion

b. Severe Concussion (>10 days time loss

Consensus Statement- Medical referral

Policy allowing body checking at the Pee Wee level (Alberta)

Body checking not allowed at the Pee Wee level (Quebec)

a. IG: IR(95%CI) 0.39 (0.23-0.67) CG:IR(95%CI): 1.47 (1.08-1.99)

b. IG:IR(95%CI): 0.08 (0.03-0.20) CG:IR(95%CI): 0.28 (0.15-0.53)

a.*IRR(95%CI): 0.27 (0.14-0.50)

b. IRR(95%CI):0.28 (0.09-0.86) 

24

2b

Hagel et al(55)

(2006)

Hockey (CAN)

HC (2000-2004, 4 seasons)

B (IG:85.3% male, CG:95.4% male)11 year olds;

IG: 82 injuries

CG: 151 injuries

Concussion

No specific concussion definition- Presenting to emergency rooms and diagnosed with concussion in organized ice hockey

Body checking not allowed (before policy change 2000-2002)

Body checking allowed (after policy change 2002-2004)

Concussion # and % overall hockey related injuries:
IG: 6 (6.7)

CG: 20 (12.6)

*RR(95%CI)=0.29 (0.12-0.71)

23

2b

Krolikowski et al(56)

(2015)

Hockey (CAN)

HC (2007-2009/2011-2012, 3 seasons)

M;Pee Wee and Bantam; Age 11-14; IG:n=828, CG: n=1269

Concussion

Validated concussion surveillance with physician diagnosis

League after head contact rule introduced

League before head contact rule introduced

us.

Pee Wee: IRR=1.89 (1.20-2.97)
Bantam:
IRR=2.27 (1.04-4.99)

13

4

Kukaswadia et al(57)

(2010)

Hockey (CAN)

HC (1997-2007, 10 years)

M; ages 7-15;

Concussion

CHIRPP database definition

Body checking not permitted in Pee Wee (age 12)

Body checking permitted in atom (ages 9-11)

IP/100 players
IG: 12.3%
CG: 12.8%

us.

10

4

Macpherson et al(58)

(2006)

Hockey (CAN)

HC (1995-2002, 8 years)

M; ages 10-15

Concussion

CHIRPP database definition

Policy disallowing Body checking (Quebec, atom/PW)

Policy allowing Body Checking (Ontario atom/PW)

# and % of injuries
10-11yrs (Atom)
IG: 14 (3%)
CG: 11 (4%)
12-13yrs (Pee Wee)
IG: 13 (2%)
CG: 40 (3%)
14-15 yrs (Bantam):*
Concussions:
IG: 20 (2%)
CG: 42 (3%)
*IG: Quebec where body checking was introduced later.
*CG: Ontario where checking was introduced earlier

Concussions:
OR body checking: 1.53 (0.92-2.53)
OR no body checking: 1.0 (referent) CI: 1.00–1.47)

Bantam, where checking allowed both provinces, higher odds of receiving a checking injury where checking introduced earlier:
(OR: 1.1; 95% CI: 0.94–1.33)

16

4

Broglio et al(59)

(2016)

Football (USA)

HC (2013-2014, 2 seasons)

M; High School Varsity;

IG: Mean(SD) age: 15.9 (0.8), N=1; n=24

CG: Mean(SD) age: 16.2 (0.8), N=1, n=26

Head Impacts

Head impact measured using the Head Impact Telemetry System (impact post filtering greater or equal to 10g of the resultant head acceleration

Policy restricting teams to conduct no more than 2 collision practices in a week

(2014 season)

Pre-policy, no restriction to number of collision practices per week

(2013 season)

Mean (SD) number of impacts:

Games and Practices (All Players)

IG: 345 (236)

CG: 592 (391)

Practices

IG: 169(134)

CG: 359(262)

Games and Practices

*RR(95%CI)= 0.58

(0.40-0.84)

Practices

*RR(95%CI)= 0.47

(0.31-0.71)

 

16

4

Cobb et al(60)

(2013)

Football (USA)

CS (2013, 1 season)

M; ages 9-12; N=3 teams; IG:N=1, n=14: CG:N=2, n=36

a. Head Contact

b. Concussion

a. Head contact accelerometry

b. No Specific concussion definition

Reduce contact practice (no more than 1/3 of weekly practice time and no more than 40 minutes in a single session)

No reduction in contact practice

a. IG: Mean= 6.2 impacts/practice/player CG: Mean: 9.5-12.9 impacts/practice/player b. IG:1 concussion reported, CG: 3 concussion reported

“head impact exposures in youth football may be appreciably reduced by limiting contact in practices”

8

4

Ruestow et al(61)

(2015)

Football (USA)

HC (2010-2011, 2 seasons)

M; Professional (NFL)

Head Injury

Injuries available from NFL publicly available playbooks as well as national and local news sources.

Does not report concussion specifically, only head injury, no definition

Introduced free kick rule (2011)

Before free kick rule (2010)

# of injuries (% of all injuries)
Kick-off Injuries
IG: n=3 (15%)
CG: n=9 (20.9%)
Punt Injuries
IG: n=4 (16%)
CG: n=4 (14.8%)

us.

16

4

 

 

 

 

 

 

 

 

 

 

 

 

Training, education, facilities

Clark et al(62)

(2015)

Football (USA)

HC (2006-2013, 8 seasons)

M; collegiate;

IG: n=437,

CG: n=417

Concussion

Alteration in brain function

Vision training (2010-2013)

No vision training (2006-2009)

IG: 1.4 concussion per 100 player seasons; CG: 9.2 concussion per 100 player seasons

*RR=0.15, p<0.001

10

4

 

 

 

 

 

 

 

 

 

 

 

 

Kerr et al(63) (2016)

Football (USA)

PC (2015, 1 season)

M; High School; IG: 3 high schools, n=204, CG: 3 high schools, n=186

Concussion

No definition specified- Medically identified

Coaches completed Heads Up Football (HUF) Certification course and used a player safety coach (PSC)

Coaches completed Heads Up Football (HUF) Certification course and did not use a player safety coach (EDU)

Concussion Rates:

Practice:

IG: IR (95%CI)= 0.09 (0-0.25) per 1000 AE

CG:IR (95%CI)= 0.73 (0.22, 1.23) per 1000AE

Game:

IG: IR (95%CI)= 0.60 (0-1.77) per 1000 AE

CG:IR (95%CI)= 4.39 (1.14, 7.65) per 1000AE

 

Practice

*IRR(95%CI): 0.12 (0.01-0.94)

Game

IRR(95%CI): 0.14 (0.02-1.11)

16

2b

Kerr et al(64)

(2015)

Football (USA)

PC (2014, 1 season)

M; ages 5-15; IG1: N=44, n=663; IG2:N=27, n=741; CG: N=29, n=29

Concussion

No definition specified- Medically identified

IG1:Head’s Up First (HUF)** educational program

IG2: HUF + PW (contact restriction in practice)

** The HUF program includes educational components on equipment fitting, tackling technique, strategies to reduce player-to-player contact, and sports medicine topics

NHUF group were also not associated with PW football association

Concussion Rates:
Practice (5-10 years)
IG1: HUF-only: IR=0.31
IG2: HUF+PW: IR=0.63
CG: NHUF: IR=0.38
 
Practice (11-15 years)
IG1: HUF-only: IR=0.14
IG2: HUF+PW: IR=0.66
CG: NHUF: IR=0.79
 
Game (5-10 years)
IG1: HUF-only: IR=0.00
IG2: HUF+PW: IR=0.00
CG: NHUF: IR=1.15
 
Game (11-15 years)
IG1: HUF-only: IR=0.99
IG2: HUF+PW: IR=2.18
CG: NHUF: IR=1.78

Concussion Rate Ratios:
Practice (5-10 years old)
HUF+PW vs NHUF: IRR= 0.82 (0.15-4.48)
HUF-only vs NHUF: IRR= 1.64 (0.37-7.34)
HUF+PW vs HUF-only: IRR= 0.50 (0.08-2.99)

Practice (11-15 years)
HUF+PW vs NHUF: IRR=0.18 (0.04-0.85)
HUF-only vs NHUF: IRR=0.84 (0.31-2.32)
HUF+PW vs HUF-only: IRR=0.21 (0.04-1.03)
 
Game (5-10 years) (no concussions in HUF+PW or HUF-only)

Game (11-15 years)
HUF+PW vs NHUF: IRR=0.56 (0.14-2.23)
HUF-only vs NHUF: IRR=1.22 (0.39-3.79)
HUF+PW vs HUF-only: IRR=0.46 (0.11-1.82)

14

2b

Swartz et al(65)

(2015)

Football (USA)

RCT (2014&2015, 19 weeks)

M; Division I; Age: us. IG: n=25, CG: n=25

Head Impacts

Head impacts measured by a xPatch sensor put directly on the skin of players right mastoid process, and data uploaded to computer after each session

HuTT program:
5 minutes of tacking training without helmets and shoulder pads
[(pre seasons – 2 times per week for 3 weeks)
(competitive season- once a week for 16 weeks)]

No HuTT program

Head impact frequency per athlete exposure:
IG: 9.99 (+/- 6.10)
CG:14.32 (+/-8.45)

us.

15

2b

Hendricks et al(66) (2015)

Rugby (ZAF)

CC (2011-2013, 3 seasons)

M; U-18, 10 videos

Concussion

Tournament physician diagnosis of concussion based on the 2009 or 2013 International Consensus on Sport Concussion

Contact techniques leading to concussion based on technical contact proficiency criterion (e.g., ruck, tackler, ball-carrier and aerial contact)
Percentage scores, which indicated the total number of events for which the criteria score was satisfied

Contact techniques not leading to concussion (NI)

IR=
5.78 /1000 player hours: (3.11-8.45)

Overall technical scores for ruck, tackler, ball-carrier and aerial contact skills between concussive and NI events were not significantly different from each other.
(proficiency scores for head placement on correct side of ball-carrier, shoulder usage and leg drive upon contact higher in NI tackle events)

21

3b

Roberts et al(67)

(1996)

Hockey (USA)

PC (1994, 3 day tournament)

M; Club Level; High School; Ages 17-19; IG: 24 games, n=882; CG: 7 games, n=217

Concussion

No specific concussion definition

Injury was defined as any ice hockey incident that required assistance from the athletic trainer

Games played using “Fair play rules” where teams get additional points in a tournament for staying under the pre-established penalty limit per game (qualifying rounds of the tournament).

Games played using regular rules used by Hockey USA without Fair play rules (Championship round of the tournament)

Notable injuries: (4/11 notable injuries were concussions)

IG: 5.7 per 1000 athlete exposures or 29.9 per 1000 player hours, 2 concussions

CG: 27.6 per 1000 athlete exposures or 126.1 per 1000 player hours, 2 concussions

us.

12

4

Smith et al (68)

(2016)

Hockey (USA)

PC (2013-2014, 11 tournaments)

M & F; Pee Wee (A and B), Bantam (A and B), U14 Girls (A and B); Ages 11-14; IG: 6 tournaments, N=62, n=948, CG: 5 tournaments, N=37, n=564

a. Concussion

b. Head Impact- no concussion

 

a. Brain injury or transient neurological dysfunction after contact – Medically identified

b. Players sustained a head hit but did not meeting concussion criteria when evaluated.

Games where Fair Play Rules (teams receive points for not receiving over a predetermined amount of penalty minutes) are emphasized and influence team standings (IFP)

Games where Fair Play was not emphasized (NIFP)

a. IG: IR (95%CI)=2.2 (0.3-7.8) per 1000 player-hours

CG: IR (95%CI)=2.3 (0.1-12.7)

b. IG: 4/ 248 IFP team games, IR: 4.3 (1.2-11.0) per 1000 player-hours

CG: 8/126 NIFP team games, IR:18.2 (7.9-35.9) per 1000 player-hours

a. RR(95%CI): 1.06 (0.1-11.7)

b. *RR (95%CI)=4.25 (1.28 to 14.11)

15

2b

Tuominen et al(69)

(2014)

Hockey (International)

PC (2006-2013, 7 seasons)

M; Elite; age: n.s.; 41 tournaments,

N=303;

n=6666;

52 concussions

Concussion

No definition specified- Medically identified

Flexible boards and glass

Standard boards and glass

u.s.

RR (95%CI)= 0.43 (95%CI: 0.18-1.01)

12

2b

Wennberg et al(70)

(2004)

Hockey (USA)

HC (2001,2002, 2 years)

M; Professional; IG: 10 games, CG: 12 games

a. Head Impact

b. Severe head contact

a. Direct Head impact: player-player into board collisions, player-player collisions or other accidental or incidental head-stick player-crossbar, player puck b. “severe head” impact: obvious, unusually severe blows to the head in any category.

International ice (Large) – 15 feet wider and 4 feet longer than standard North American NHL rink

NHL ice (small)- Standard North American rink (200 feet x 85 feet dimensions

Means of direct collisions in games (SD):

Direct Head contact
IG: 5.4 (2.5)
CG: 11.6 (6.4)

Severe Head contact
IG: 1.1 (+/-0.8)
CG: 0.3 (+/-0.4)

Two-sample t-test:

Direct head contact
P=0.007

Severe head contact
P=0.006

12

4

Wennberg et al(71)

(2005)

Hockey (CAN/CZ/FIN)

HC (2002-2004, 3 seasons)

M; World Juniors, IG1: 7 games, IG2: 6 games, CG:: 6 games

a. Head Impact

b. severe head contact

Direct Head impact (player-player into board collisions, player-player collisions or other accidental or incidental head-stick, player-crossbar, player puck
“severe head” impact was used to denote obvious, unusually severe blows to the head in any category.

IG1: Large Ice size (100 ft wide)
IG2:Intermediate Ice size (94 ft wide)

Small Ice size (85ft wide)

Mean (SD) Direct Head Contacts:
IG1 (Large Ice Surface): 13.4 (3.9)
IG2 (Intermediate Ice Surface): 15.7 (2.9)
CG (Small ice Surface) 26.3 (6.6)

Mean (SD) Severe Head Contacts:
IG1 (Large Ice Surface): 0.3 (0.4)
IG2 (Intermediate Ice Surface): 0.5 (0.4)
CG (Small ice Surface) 1.3 (0.4)

u.s

10

4

Country: CAN-Canada; USA-United States; NZ-New Zealand; AUS-Australia; ENG-England; ZAF- South Africa

Study Designs: CS- Crossectional; RCT-Randomized controlled trial; PC-Prospective Cohort; HC-Historical Cohort; nCC-nested Case Control; Pexp-Pre-experimental

Participant Information: F-Female; M-Male; B- Male and Female; IG-Intervention group; CG-Control Group; N- number of teams; n-number of participants; us.-unspecified;

RR-Risk ratio; AT-Athletic Trainer; CHIRPP-Children's Hospital Injury Reporting Program

WIPSS- Type of mouthguard characterized as 2-layered boil and bite (type 2) mouthguard

**- adjusted for actual and estimated previous concussions