Table 3.
Association between sibling patterns and: (a) first clinical diagnosis (FCD) and (b) asthma among controls
| Controls* | FCD cases* | Controls no asthma‡ | Controls asthma‡ | |||||
|---|---|---|---|---|---|---|---|---|
| n = 539 | n = 279 | n = 421 | n = 133 | |||||
| Sibling patterns | n (%) | n (%) | adj OR† for FCD (95% CI) | P-value | n (%) | n (%) | adj OR§ for asthma (95% CI) | P-value |
| Sibling size (continuous) | – | – | 0·97 (0·89–1·06) | 0·49 | – | – | 0·84 (0·74–0·97) | 0·02 |
| No. older siblings | ||||||||
| None | 209 (39·9) | 96 (35·2) | Ref | 150 (36·7) | 64 (49·6) | Ref | ||
| 1 | 144 (27·5) | 82 (30·0) | 1·15 (0·80–1·67) | 117 (28·6) | 30 (23·3) | 0·61 (0·36–1·03) | ||
| 2 | 95 (18·1) | 55 (20·2) | 1·12 (0·73–1·71) | 76 (18·6) | 21 (16·3) | 0·70 (0·39–1·26) | ||
| 3 or more | 76 (14·5) | 40 (14·6) | 1·09 (0·69–1·71) | 0·66 | 66 (16·1) | 14 (10·9) | 0·50 (0·25–0·98) | 0·04 |
| Any older siblings | 315 (60·1) | 177 (64·8) | 1·13 (0·82–1·54) | 0·46 | 259 (63·3) | 65 (50·4) | 0·61 (0·40–0·93) | 0·02 |
| No. younger siblings | ||||||||
| None | 153 (29·2) | 103 (37·7) | Ref | 127 (31·1) | 30 (23·3) | Ref | ||
| 1 | 164 (31·3) | 77 (28·2) | 0·69 (0·47–1·03) | 124 (30·3) | 46 (35·7) | 1·46 (0·84–2·53) | ||
| 2 | 129 (24·6) | 56 (20·5) | 0·65 (0·42–1·00) | 92 (22·5) | 37 (28·7) | 1·83 (1·03–3·25) | ||
| 3 or more | 78 (14·9) | 37 (13·6) | 0·70 (0·43–1·15) | 0·07 | 66 (16·1) | 16 (12·4) | 1·02 (0·50–2·05) | 0·46 |
| Any younger siblings | 371 (70·8) | 170 (62·3) | 0·68 (0·49–0·95) | 0·03 | 282 (68·9) | 99 (76·7) | 1·47 (0·91–2·38) | 0·12 |
| Infant sibling exposure¶ | ||||||||
| <1 years | 222 (41·2) | 133 (47·7) | Ref | 186 (44·2) | 44 (33·1) | Ref | ||
| 1–<3 years | 216 (40·1) | 103 (36·9) | 0·85 (0·61–1·18) | 155 (36·8) | 64 (48·1) | 1·70 (1·07–2·71) | ||
| 3–<5 years | 76 (14·1) | 35 (12·5) | 0·82 (0·51–1·31) | 62 (14·7) | 17 (12·8) | 1·30 (0·68–2·49) | ||
| ≥5 years | 25 (4·6) | 8 (2·9) | 0·51 (0·23–1·17) | 0·10 | 18 (4·3) | 8 (6·0) | 2·04 (0·81–5·13) | 0·09 |
*
Matched FCD cases and controls with complete data.
†
Matched odds ratios adjusted (adjOR) for level of education and ever smoker.
‡
All interviewed controls with allergy data, including those not matched to a participating case.
§
OR adjusted for age, gender, level of education and ever smoker.
¶
Cumulative exposure to infant siblings (aged ≤ 2 years) before the subject was aged 6 years. FCD: a first clinical diagnosis of central nervous system demyelination; CI: confidence interval.