Table 3.
Rate of hospitalisation for selected child outcomes and smoking status at first booking for respiratory infections, asthma and bronchiolitis for (A) the whole period of follow-up; and for two separate periods of follow-up: (B) from birth to first birthday and (C) from first birthday to fifth birthday
| (A) Follow-up from birth to fifth birthday | ||||||||||
| Smoking status at first booking | Infants at risk (N) | Acute upper and lower respiratory infections | Asthma | Bronchiolitis | ||||||
| N | Column % | Row % | N | Column % | Row % | N | Column % | Row % | ||
| 697 003 | 56 615 | 100.0 | 8.1 | 7549 | 100.0 | 1.1 | 24 088 | 100.0 | 3.5 | |
| Never smoked | 391 861 | 30 549 | 54.0 | 7.8 | 3678 | 48.7 | 0.9 | 11 354 | 47.1 | 2.9 |
| Current smoker | 159 819 | 14 945 | 26.4 | 9.4 | 2412 | 32.0 | 1.5 | 7939 | 33.0 | 5.0 |
| Former smoker | 59 326 | 4966 | 8.8 | 8.4 | 654 | 8.7 | 1.1 | 1821 | 7.6 | 3.1 |
| Unknown/missing | 85 997 | 6155 | 10.9 | 7.2 | 805 | 10.7 | 0.9 | 2974 | 12.3 | 3.5 |
| (B) Follow-up from birth to first birthday | PAF (%) | ||||||
| Acute upper and lower respiratory infections | Admission for specified outcome | Infants at risk (N) | Crude HR | Adjusted* HR | |||
| N | Column % | Row % | |||||
| 18 541 | 100.0 | 2.7 | 697 003 | HR (95% CI) | HR (95% CI) | ||
| Never smoked | 9573 | 51.6 | 2.4 | 391 861 | 1.00 (reference) | 1.00 (reference) | 6.7 |
| Current smoker | 5537 | 29.9 | 3.5 | 159 819 | 1.43 (1.38 to 1.48) | 1.29 (1.25 to 1.34) | |
| Former smoker | 1484 | 8.0 | 2.5 | 59 326 | 1.02 (0.97 to 1.08) | 0.97 (0.92 to 1.03) | |
| Unknown/missing | 1947 | 10.5 | 2.3 | 85 997 | 0.93 (0.89 to 0.98) | 0.89 (0.84 to 0.93) | |
| Asthma | 606 | 100.0 | 0.1 | 697 003 | |||
| Never smoked | 242 | 39.9 | 0.1 | 391 861 | 1.00 (reference) | 1.00 (reference) | 21.9 |
| Current smoker | 248 | 40.9 | 0.2 | 159 819 | 2.51 (2.10 to 3.00) | 2.15 (1.80 to 2.57) | |
| Former smoker | 46 | 7.6 | 0.1 | 59 326 | 1.25 (0.91 to 1.72) | 1.18 (0.86 to 1.62) | |
| Unknown/missing | 70 | 11.6 | 0.1 | 85 997 | 1.33 (1.02 to 1.73) | 1.29 (0.99 to 1.69) | |
| Bronchiolitis | 20 399 | 100.0 | 2.9 | 697 003 | |||
| Never smoked | 9499 | 46.6 | 2.4 | 391 861 | 1.00 (reference) | 1.00 (reference) | 10.1 |
| Current smoker | 6861 | 33.6 | 4.3 | 159 819 | 1.79 (1.73 to 1.84) | 1.43 (1.38 to 1.48) | |
| Former smoker | 1534 | 7.5 | 2.6 | 59 326 | 1.07 (1.01 to 1.13) | 1.03 (0.97 to 1.08) | |
| Unknown/missing | 2505 | 12.3 | 2.9 | 85 997 | 1.21 (1.16 to 1.27) | 1.15 (1.09 to 1.21) | |
| (C) Follow-up from first birthday to fifth birthday | PAF (%) | ||||||
| Acute upper and lower respiratory infections | Admission for specified outcome | Infants at risk (N)† | Crude HR | Adjusted* HR | |||
| N | Column % | Row % | |||||
| 38 074 | 100.0 | 5.7 | 662 454 | HR (95% CI) | HR (95% CI) | ||
| Never smoked | 20 976 | 55.1 | 5.6 | 373 436 | 1.00 (reference) | 1.00 (reference) | −0.2 |
| Current smoker | 9408 | 24.7 | 6.2 | 151 010 | 1.09 (1.07 to 1.12) | 0.99 (0.97 to 1.02) | |
| Former smoker | 3482 | 9.1 | 6.1 | 56 645 | 1.09 (1.06 to 1.13) | 1.04 (1.00 to 1.08) | |
| Unknown/missing | 4208 | 11.1 | 5.2 | 81 363 | 0.95 (0.92 to 0.98) | 0.90 (0.87 to 0.94) | |
| Asthma | 6943 | 100.0 | 1.0 | 679 588 | |||
| Never smoked | 3436 | 49.5 | 0.9 | 382 327 | 1.00 (reference) | 1.00 (reference) | 7.1 |
| Current smoker | 2164 | 31.2 | 1.4 | 156 123 | 1.51 (1.43 to 1.59) | 1.29 (1.22 to 1.37) | |
| Former smoker | 608 | 8.8 | 1.0 | 58 025 | 1.16 (1.07 to 1.27) | 1.10 (1.00 to 1.20) | |
| Unknown/missing | 735 | 10.6 | 0.9 | 83 113 | 1.04 (0.96 to 1.12) | 1.01 (0.92 to 1.10) | |
| Bronchiolitis | 3689 | 100.0 | 0.6 | 660 119 | |||
| Never smoked | 1855 | 50.3 | 0.5 | 373 219 | 1.00 (reference) | 1.00 (reference) | 4.0 |
| Current smoker | 1078 | 29.2 | 0.7 | 149 609 | 1.45 (1.34 to 1.56) | 1.16 (1.08 to 1.25) | |
| Former smoker | 287 | 7.8 | 0.5 | 56 561 | 1.02 (0.90 to 1.15) | 0.98 (0.87 to 1.11) | |
| Unknown/missing | 469 | 12.7 | 0.6 | 80 730 | 1.18 (1.06 to 1.30) | 1.11 (1.01 to 1.24) | |
*Adjusted for: maternal age; infant gender, SIMD; mothers socioeconomic status; fathers socioeconomic status; parity; mode of delivery, infant feeding at 6–8 weeks and country of birth.
†The number of infants at risk from their first birthday to fifth birthday is the total number of infants aged 0–1 year (697 003) minus the specific outcome cases and any deaths or migration from 0–1 year.
PAF, population attributable fraction; SIMD, Scottish Index of Multiple Deprivation.