Multivariable main associations between increasing childhood bronchitis severity by age 7 and lung function at age 53 years
| Adult outcome at age 53 | Childhood bronchitis severity at age 7(β (95% CI) N=2379)†‡§ | ||||
| Lung function¶ | Case (n) | Model (N) | Non-recurrent (n=686) | Recurrent, non-protracted (n=427) | Recurrent-protracted (n=28) |
| Pre-BD zFEV1 | – | 2379 | –0.02 (–0.22, +0.17) | –0.15 (–0.39, +0.08) | –0.10 (–0.88, +0.68) |
| Post-BD zFEV1 | – | 2354 | –0.09 (–0.19, +0.01) | –0.16 (–0.28, –0.05)** | –0.09 (–0.47, +0.29) |
| BDR Δ FEV1 (mL) | – | 2344 | –4.8 (–17, +8) | –0.05 (–15, +15) | –0.10 (–50, +50) |
| Pre-BD zFVC | – | 2378 | –0.02 (–0.18, +0.13) | –0.10 (–0.28, +0.08) | +0.01 (–0.59, +0.62) |
| Post-BD zFVC | – | 2354 | –0.08 (–0.16,+0.01) | –0.09 (–0.19,+0.01) | –0.005 (–0.34,+0.33) |
| BDR Δ FVC (mL) | – | 2343 | –3.3 (–17, +11) | +8.7 (–8.1, +26) | –10 (–66, +46) |
| Pre-BD zFEV1/FVC | – | 2378 | –0.03 (–0.12, +0.06) | –0.09 (–0.19, +0.02) | –0.19 (–0.54, +0.16) |
| Pre-BD airflow obstruction†† | 191 | 2378 | 1.12 (0.79–1.61) | 1.64 (1.11–2.40)* | § |
| Post-BD zFEV1/FVC | – | 2354 | –0.03 (–0.11, +0.06) | –0.12 (–0.22, –0.02)* | –0.15 (–0.49, +0.19) |
| Post-BD airflow obstruction** | 103 | 2342 | 1.16 (0.72–1.87) | 1.46 (0.87, 2.47) | § |
| Spirometric restriction** | 53 | 2239 | 1.67 (0.89–3.11) | 1.99 (0.97–4.01)†† | § |
| zTLco | – | 2285 | +0.03 (–0.06, +0.12) | +0.09 (–0.02, +0.20) | +0.51 (+0.15, +0.88)** |
| zKco | – | 2285 | +0.05 (–0.04, +0.15) | +0.18 (+0.06, +0.29)** | +0.51 (+0.13, +0.89)** |
| zVA | – | 2285 | –0.02 (–0.11, +0.07) | –0.09 (–0.20, +0.02) | +0.06 (–0.30, +0.42) |
*P<0.05, **p<0.01.
†Parent-reported bronchitis by age 7 categorised into none (reference=1, not shown), non-recurrent, recurrent (>5 episodes of coughing phlegm or ‘loose, or rattly’ cough lasting <1 month on average), and recurrent-protracted (>5 episodes, ≥1 month average duration).
‡Multivariable models were adjusted for rurality of school, paternal occupation, family history of bronchitis, sibling number, maternal and paternal smoking, and participant sex.
§Cells that had <5 cases; see table 2 for case numbers.
¶Lung function measured in z-scores which, by definition, has a mean of 0 and SD of 1.
**ORs: pre-BD airflow obstruction (zFEV1/FVC <LLN); spirometric restriction (post-BD zFVC <LLN and zFEV1/FVC ≥LLN).
††P=0.050.
BD, bronchodilator; BDR, bronchodilator response; CB, chronic bronchitis; FEV1, forced expiratory volume in 1 s; FVC, forced vital capacity; Kco, carbon monoxide transfer coefficient; LLN, lower limit of normal; TLco, carbon monoxide transfer factor of the lung; VA, alveolar volume.