Table 1.
Recurrence of cerebral palsy (CP) among relatives. Singletons and twins born in Norway 1967-2002 surviving first three years of life
| Relatives | Prevalence of CP (per 1000) | Relative risk (95% CI) | |
|---|---|---|---|
| Crude | Adjusted | ||
| Twins | |||
| Prevalence in twin population | 228/45 116 (5.1) | 1 (reference) | — |
| Proband-wise concordance rate | 18/228 (78.9) | 15.6 (9.8 to 24.8) | — |
| First degree | |||
| Full siblings: | |||
| Sibling without CP | 1929/1 226 413 (1.6) | 1 (reference) | 1 (reference) |
| Sibling with CP | 30/2014 (14.9) | 9.5 (6.6 to 13.5) | 9.2 (6.4 to 13.1)* |
| Parent-offspring: | |||
| Parent without CP | 813/622 480 (1.3) | 1 (reference) | — |
| Parent with CP | 2/237 (8.5) | 6.5 (1.6 to 25.6) | — |
| Second degree | |||
| Half siblings: | |||
| Half sibling without CP | 762/354 163 (2.2) | 1 (reference) | 1 (reference) |
| Half sibling with CP | 5/774 (6.5) | 3.0 (1.2 to 7.2) | 3.0 (1.1 to 8.6)† |
| Aunt/uncle-niece/nephew: | |||
| Aunt/uncle without CP | 1930/1 342 559 (1.4) | 1 (reference) | — |
| Aunt/uncle with CP | 3/2360 (1.3) | 0.9 (0.3 to 2.7) | — |
| Third degree | |||
| First cousin with CP | 8472/5 156 811 (1.6) | 1 (reference) | — |
| First cousin without CP | 23/9157 (2.5) | 1.5 (0.9 to 2.7) | — |
*Adjusted for maternal age at birth of older sibling (<20, 20-24, 25-29, 30-34, ≥35), maternal educational level (below high school, high school, above high school), and period of first birth (1967-71, 1972-77, 1978-84, 1985-91, 1992-2002).
†Adjusted for parental age at birth of older sibling (<20, 20-24, 25-29, 30-34, ≥35 for mothers, extended to 35-39, 40-44, ≥45 for fathers), parental educational level (below high school, high school, above high school), and period of first birth (1967-71, 1972-77, 1978-84, 1985-91, 1992-2002).