Maintaining optimal lung function throughout life is important not only for respiratory health but also for overall health and longevity. With emerging evidence on the clinical significance of lung function at multiple windows throughout life, there has been an increasing number of studies on lung function trajectories1 including by Zhang et al in this issue.2

The term ‘lung function trajectory’ refers to how lung function tracks over time. The lungs start to develop from the first trimester of pregnancy, grow throughout childhood and adolescence, mature in early adulthood and then gradually age. As a result, lung function increases over time before reaching a peak in early adulthood, then plateaus for a while before declining with age. Lung function is influenced by adverse host factors and environmental exposures. Indeed, there are multiple and dynamic interactions between gene (G) and environment (E) throughout the lifespan (T), termed as GETomics,3 causing abnormalities at one or more life windows leading to impaired development, reduced growth, shortened plateau and accelerated decline. Due to varying GETomics, there can be substantial variation in change in lung function over time making up a range of lung function trajectories.

Most studies on lung function trajectories were only able to capture either lung growth or decline phases.1 For example, studies from childhood to early adulthood (growth phase) including the Manchester Asthma and Allergy Study(MAAS, 5–16 years), the Avon Longitudinal Study of Parents and Children (ALSPAC, 8–24 years), the Australian Perth Infant Asthma Follow-up (PIAF, 1–18 years) and the Raine Study (6–22 years) reported multiple lung function trajectories that are parallel to the average trajectory.4 5 The Tasmanian Longitudinal Health Study (TAHS) was the first to investigate lung function trajectories that capture both lung growth and decline (7–53 years).6 7 It not only showed two …