Does childhood respiratory disease predict lung function trajectories?

RATIONALE: Lung function trajectories formed in early life influence long-term health. However, opportunities to intervene and improve individuals' trajectories are limited by the lack of detailed clinical phenotyping. OBJECTIVE: To assess if childhood respiratory disease predicts lung function trajectory. METHODS: The study included the first generation of children from the Avon Longitudinal Study of Parents and Children. Childhood respiratory diseases were identified using linked electronic health records. Spirometry was measured at ages 8, 15 and 24 years, from which four lung function trajectories were previously defined. Logistic and ordinal logistic models were used to assess the association between respiratory disease and lung function trajectories. To clinically phenotype the trajectory groups further, objective measures of airways disease activity, respiratory prescriptions, and social and environmental risk factors were compared across trajectory groups. RESULTS: 10,332 children were included in the study. Among the childhood respiratory diseases examined, only asthma was associated with lower lung function trajectory (OR 1.40, 95% CI 1.18-1.66). Notably, neither respiratory infection nor premature birth showed an association with lung function trajectory. Asthma was most frequently observed in individuals within subnormal trajectories, particularly in the Persistently Low group, where it was present in 44% (63/142) of cases. A substantial proportion of individuals with asthma from subnormal trajectories(33%, 177/532) had not been prescribed an inhaled corticosteroid, indicating potential undertreatment. Objective measures of airways disease were consistently more common in the subnormal trajectory groups. Interestingly, 45% (64/142) of those in the Persistently Low trajectory had no respiratory diagnosis. CONCLUSIONS: Asthma is a predictor of lung function trajectory and early life optimisation of asthma treatment represents a possible means of modifying trajectory. Many individuals in the lowest trajectories are unknown to healthcare services and further work needs to be done to better characterise this group.