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 | IRa | 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)