Table 5.
Association of symptoms and disease labels with total and older siblings, before and after adjustment for covariates
| Symptom (6 to 7-year-olds) | Total siblings (odds ratio per additional sibling) All children as in Table 1 | Total siblings (odds ratio per additional sibling) Before adjustment, in children with covariate data | Total siblings (odds ratio per additional sibling) After adjustment, in children with covariate data | |||
|---|---|---|---|---|---|---|
| OR (95% CL) | P value | OR (95% CL) | P value | OR (95% CL) | P value | |
| Wheeze ever | 0.96 (0.94, 0.98) | < 0.0001 | 0.96 (0.94, 0.98) | < 0.0001 | 0.96 (0.94, 0.98) | < 0.0001 |
| Wheeze in last 12 months | 0.99 (0.97, 1.01) | 0.35 | 0.99 (0.97, 1.02) | 0.56 | 0.99 (0.96, 1.01) | 0.19 |
| Severe wheeze in last 12 months | 1.06 (1.03, 1.09) | < 0.0001 | 1.06 (1.02, 1.09) | 0.0007 | 1.03 (1.00, 1.06) | 0.07 |
| Asthma ever | 0.98 (0.96, 1.00) | 0.11 | 0.99 (0.96, 1.01) | 0.22 | 0.98 (0.96, 1.01) | 0.12 |
| Rhinitis ever | 0.94 (0.93, 0.96) | < 0.0001 | 0.94 (0.93, 0.96) | < 0.0001 | 0.94 (0.93, 0.96) | < 0.0001 |
| Rhinoconjunctivitis in last 12 months | 0.98 (0.96, 1.00) | 0.09 | 0.99 (0.97, 1.01) | 0.37 | 0.99 (0.97, 1.01) | 0.36 |
| Severe rhinoconjunctivitis | 1.04 (0.97, 1.11) | 0.31 | 1.05 (0.97, 1.13) | 0.21 | 1.03 (0.95, 1.11) | 0.48 |
| Hay fever ever | 0.92 (0.90, 0.95) | < 0.0001 | 0.92 (0.89, 0.94) | < 0.0001 | 0.92 (0.90, 0.95) | < 0.0001 |
| Itchy rash ever | 1.00 (0.98, 1.02) | 0.81 | 1.00 (0.98, 1.02) | 0.67 | 1.00 (0.98, 1.02) | 0.81 |
| Itchy flexural rash in last 12 months | 1.00 (0.98, 1.02) | 0.91 | 1.00 (0.98, 1.03) | 0.72 | 1.01 (0.98, 1.03) | 0.59 |
| Severe itchy flexural rash | 1.18 (1.11, 1.24) | < 0.0001 | 1.18 (1.11, 1.26) | < 0.0001 | 1.13 (1.05, 1.20) | 0.0004 |
| Eczema ever | 0.93 (0.91, 0.95) | < 0.0001 | 0.93 (0.91, 0.95) | < 0.0001 | 0.95 (0.93, 0.97) | < 0.0001 |
| Symptom (6 to 7-year-olds) | Older siblings (adjusted for younger siblings) All children as in Table 2 | Older siblings (adjusted for younger siblings) Before adjustment, in children with covariate data | Older siblings (adjusted for younger siblings) After adjustment, in children with covariate data | |||
|---|---|---|---|---|---|---|
| OR (95% CL) | P value | OR (95% CL) | P value | OR (95% CL) | P value | |
| Wheeze ever | 0.97 (0.95, 0.98) | < 0.0001 | 0.97 (0.95, 0.99) | 0.002 | 0.98 (0.96, 1.00) | 0.04 |
| Wheeze in last 12 months | 1.01 (0.99, 1.03) | 0.38 | 1.01 (0.99, 1.04) | 0.43 | 1.01 (0.98, 1.04) | 0.45 |
| Severe wheeze in last 12 months | 1.07 (1.04, 1.10) | < 0.0001 | 1.06 (1.03, 1.10) | 0.0009 | 1.05 (1.01, 1.09) | 0.02 |
| Asthma ever | 0.99 (0.97, 1.01) | 0.27 | 0.99 (0.96, 1.02) | 0.52 | 1.00 (0.97, 1.03) | 0.82 |
| Rhinitis ever | 0.93 (0.91, 0.94) | < 0.0001 | 0.93 (0.91, 0.95) | < 0.0001 | 0.93 (0.91, 0.95) | < 0.0001 |
| Rhinoconjunctivitis in last 12 months | 0.98 (0.96, 1.00) | 0.03 | 0.98 (0.96, 1.01) | 0.25 | 0.99 (0.97, 1.02) | 0.69 |
| Severe rhinoconjunctivitis | 1.00 (0.93, 1.07) | 0.89 | 1.00 (0.91, 1.09) | 0.92 | 1.01 (0.92, 1.10) | 0.90 |
| Hay fever ever | 0.91 (0.89, 0.93) | < 0.0001 | 0.90 (0.87, 0.93) | < 0.0001 | 0.91 (0.88, 0.94) | < 0.0001 |
| Itchy rash ever | 0.98 (0.96, 1.00) | 0.23 | 0.97 (0.95, 0.99) | 0.01 | 0.97 (0.95, 1.00) | 0.03 |
| Itchy flexural rash in last 12 months | 0.98 (0.96, 1.00) | 0.09 | 0.98 (0.96, 1.01) | 0.19 | 0.98 (0.95, 1.01) | 0.24 |
| Severe itchy flexural rash | 1.14 (1.08, 1.20) | < 0.0001 | 1.14 (1.06, 1.22) | 0.0004 | 1.09 (1.01, 1.18) | 0.03 |
| Eczema ever | 0.90 (0.88, 0.92) | < 0.0001 | 0.90 (0.88, 0.92) | < 0.0001 | 0.92 (0.90, 0.94) | < 0.0001 |
All analyses are adjusted for sex, region, language and national GNI per capita. Additional covariates for the total siblings analysis: gender, maternal education, parental smoking, cat, dog, truck traffic and cooking fuels (all at age 6–7). Additional covariates for the older siblings analysis: gender, maternal education, mother smoking in the first year of life, cat, dog and farm animal exposure in the first year, birthweight, breastfeeding, paracetamol use in the first year, antibiotic use in the first year.