Table 2.

First severe head injury as a risk factor of Amyotrophic Lateral Sclerosis

	ALS Cases No.	Controls No.	OR*	95% CI
Years before index date
No injury	3,888	19,632	Referent	-
≤1	39	50	3.9	2.6–6.1
>1 to ≤3	14	64	1.1	0.6–1.9
>3	63	274	1.2	0.9–1.5
>3 to ≤5	12	64	0.9	0.5–1.8
>5 to ≤10	31	111	1.4	0.9–2.1
>10	20	99	1.0	0.6–1.6

^*Odds ratios were derived from conditional logistic regression models, adjusted for socio-economic status and region of residence.