Table 1. Subjects excluded from the analysis by reason for exclusion and characteristics of those included.
| Cases | Controls | |
|---|---|---|
| Total available | 2692 (100%) | 4864 (100%) |
| Excluded (%) | 162 (6%)a | 377 (8%) |
| Diagnosed under 3 months of age | 56 | — |
| Down's syndrome | 32 | 3 |
| Multiple birth | 60 | 108 |
| Unmatchedb | 14 | 266 |
| Included (%) | 2530 (94%) | 4487 (92%) |
| Total included | 2530 (100%) | 4487 (100%) |
| Sex (%) | ||
| Males | 1413 (56%) | 2487 (55%) |
| Females | 1117 (44%) | 2000 (45%) |
| Age at diagnosis (%) | ||
| <1 year | 189 (7%) | 351 (8%) |
| 1 year | 254 (10%) | 473 (11%) |
| 2–5 years | 1069 (42%) | 1926 (43%) |
| 6+ years | 1018 (40%) | 1737 (39%) |
a
Three cases diagnosed under 3 months of age also had Down's syndrome, and two cases with Down's syndrome were also part of a multiple birth.
b
Cases or controls who did not have a corresponding matched case or control after the exclusions had been made.