Table 3.

Age specific hazard ratios (HR) for epilepsy in OS twins compared with SS twins

Age group and exposure status	Female					Males
	Population	Epilepsy cases	IRa	Crude HR	Adjusted HR [95% CI]b	Population	Epilepsy cases	IRa	Crude HR	Adjusted HR [95% CI]b
<1 year
SS	19,186	47	26.66	Ref	Ref	20,207	63	33.99	Ref	Ref
OS	11,078	19	18.65	0.70	0.74[0.42-1.30]	11,080	34	33.40	0.98	0.98[0.63-1.51]
1-9 years
SS	19,039	130	9.04	Ref	Ref	19,990	176	11.60	Ref	Ref
OS	11,004	86	10.55	1.16	1.17[0.89-1.55]	10,992	87	10.69	0.92	0.95[0.73-1.23]
10-18 years
SS	12,379	73	8.81	Ref	Ref	13,150	70	8.01	Ref	Ref
OS	6,722	35	8.38	0.95	0.95[0.63-1.44]	6,713	34	8.16	1.01	0.98[0.65-1.48]
19-35 years
SS	6,282	32	7.06	Ref	Ref	6,533	26	5.19	Ref	Ref
OS	2,805	12	6.05	0.86	0.87[0.45-1.69]	2,789	7	3.58	0.69	0.72[0.31-1.66]

^aIncidence rate (/10,000 person-years)

^bHazard ratios, adjusted for maternal age at time of birth (<25, 25-29, 30-34, 35-39, 40+ years), paternal age at time of birth (<30, 30-39, 40+ years, missing), maternal and paternal highest completed education (primary and lower secondary, upper and post-secondary, tertiary, and missing), and calendar year (1977-1984, 1985-1994, 1995-1999, 2000-2004, 2005-2009)