Table 4

Cluster adjusted risk ratios and Cox proportional hazard ratios comparing the incidence of SRC between the HG and NoHG groups

	n	SRC	% SRC	Multivariate risk ratio		Multivariate HR
	n	SRC	% SRC	95% CI	P value	95% CI	P value
Intent to treat
Overall	3050	130	4.3
All no headgear	1545	68	4.4	Reference	–	Reference	–
All headgear	1505	62	4.1	0.98 (0.62 to 1.56)	0.946	0.98 (0.64 to 1.51)	0.935
Males—no headgear	546	8	1.5	Reference	–	Reference	–
Males—headgear	474	14	3.0	1.83 (0.60 to 5.53)	0.286	2.00 (0.63 to 6.43)	0.242
Females—no headgear	999	60	6.0	Reference	–	Reference	–
Females—headgear	1031	48	4.7	0.90 (0.55 to 1.48)	0.683	0.86 (0.54 to 1.36)	0.520
As treated
All no headgear	1546	75	4.9	Reference	–	Reference	–
All headgear	1504	55	3.7	0.63 (0.37 to 1.08)	0.091	0.78 (0.48 to 1.25)	0.303
Males—no headgear	548	10	1.8	Reference	–	Reference	–
Males—headgear	472	12	2.5	0.93 (0.27 to 3.20)	0.909	1.33 (0.43 to 4.11)	0.623
Females—no headgear	998	65	6.5	Reference	–	Reference	–
Females—headgear	1032	43	4.2	0.64 (0.38–1.08)	0. 094	0.70 (0.43 to 1.15)	0.154

Multivariable analysis consisted of Poisson regression and Cox proportional hazards survival analysis controlling for age, sex, year, concussion in the last year and symptom severity group as covariates and school cluster effect.
As treated designation is based on majority headgear use (yes/no) for those without an SRC, and whether they were wearing headgear when SRC occurred for those with SRC.
HG, headgear group; NoHG, no headgear group; SRC, sport-related concussion.