Risk of epilepsy in opposite-sex and same-sex twins: a twin cohort study

Table 2 Hazard ratios (HR) for epilepsy in OS twins compared with SS twins in females and males

Exposure status	Both twins of the SS twin pair were included in the reference					One twin of the SS twin pair was randomly selected as the reference
						Sample 1	Sample 2
	Population	Epilepsy cases	IR^a	Crude HR	Adjusted HR [95% CI]^b	Adjusted HR [95% CI]^b	Adjusted HR [95% CI]^b
The SS female twins	19,186	282	9.74	Ref	Ref	Ref	Ref
The OS female twins	11,078	152	9.91	1.00	1.01[0.83-1.24]	1.03[0.81-1.30]	1.00[0.79-1.25]
The SS male twins	20,207	335	10.9	Ref	Ref	Ref	Ref
The OS male twins	11,080	162	10.6	0.93	0.94[0.78-1.14]	1.00[0.80-1.24]	0.89[0.72-1.11]

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

ISSN: 2042-6410