Abstract
Rationale: Airway remodeling may lead to irreversible loss of lung function in asthma, but population prevalence, risk factors and time course are not known.
Methods: The impact of childhood asthma, airway responsiveness, atopy and smoking on airway remodeling was investigated in a New Zealand birth cohort studied longitudinally to age 26. A low post bronchodilator FEV1/VC ratio at age 18 or 26 was used to define airway remodeling. 'Normal' study members (no history of asthma ever, no wheezing in the last year, no smoking ever) were used to determine gender and age-specific reference values for this ratio. The lower limit of normal was defined as the mean ratio minus 1.96 standard deviations.
Results: A low post bronchodilator FEV1/VC ratio was found in 7.4% and 6.4% of study members at age 18 and age 26, and in 4.6% at both assessments. Lung function was low throughout childhood in those with consistently low ratios. Those with low ratios also showed a greater decline in the pre-bronchodilator FEV1/VC ratio from age 9 to 26 compared with those with normal ratios (males: -12% versus -6%, p<0.0001, and females: -10.5% versus -5.5%, p<0.01). Asthma, male sex, airway hyperresponsiveness and low lung function in childhood were independently associated with an accelerated decline in lung function and decreased reversibility, features consistent with airway remodeling.
Conclusions: Airway remodeling in asthma is evident in childhood and continues into adult life.