Table 5

Multivariable main associations between increasing childhood bronchitis severity by age 7 and lung function at age 53 years

Adult outcome at age 53Childhood 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 zFEV12379–0.02 (–0.22, +0.17)–0.15 (–0.39, +0.08)–0.10 (–0.88, +0.68)
Post-BD zFEV12354–0.09 (–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 zFVC2378–0.02 (–0.18, +0.13)–0.10 (–0.28, +0.08)+0.01 (–0.59, +0.62)
Post-BD zFVC2354–0.08 (–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/FVC2378–0.03 (–0.12, +0.06)–0.09 (–0.19, +0.02)–0.19 (–0.54, +0.16)
Pre-BD airflow obstruction††19123781.12 (0.79–1.61)1.64 (1.11–2.40)*§
Post-BD zFEV1/FVC2354–0.03 (–0.11, +0.06)–0.12 (–0.22, –0.02)*–0.15 (–0.49, +0.19)
Post-BD airflow obstruction**10323421.16 (0.72–1.87)1.46 (0.87, 2.47)§
Spirometric restriction**5322391.67 (0.89–3.11)1.99 (0.97–4.01)††§
zTLco2285+0.03 (–0.06, +0.12)+0.09 (–0.02, +0.20)+0.51 (+0.15, +0.88)**
zKco2285+0.05 (–0.04, +0.15)+0.18 (+0.06, +0.29)**+0.51 (+0.13, +0.89)**
zVA2285–0.02 (–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.