Background
Lifetime lung function is related to quality of life and longevity. Over the lifespan, individuals follow different lung function trajectories. It is important to identify these trajectories, their determinants and outcomes but no study has done this beyond the fourth decade.
Methods
We modelled trajectories of forced expiratory volume in 1 second (FEV1) measured at 7, 13, 18, 45, 50 and 53 years (n=2438). The trajectories identified were then related to childhood factors and Chronic Obstructive Pulmonary Disease (COPD) risk.
Findings
Six trajectories were identified: “early below average, accelerated decline” (4%, n=97), “persistently low” (5·6%, n=136), “below average” (31·6%, n=772), “persistently high” (12·1%, n=293), “early low, accelerated growth, normal decline” (8%, n=196), and “average” (38·7%, n=944). The first three trajectories had increased risk of COPD at age 53 compared with the average group: OR 35(95%CI 19·5-64); 9·5(4·5-20·6); and 3·7(1·9-6·9) respectively. Early-life predictors of the three trajectories included childhood asthma, bronchitis, pneumonia, hayfever, eczema, parental asthma, and maternal smoking. Personal smoking and active adult asthma increased the impact of maternal smoking and childhood asthma respectively on the “early below average, accelerated decline” trajectory.
Interpretation
We identified six potential FEV1 trajectories, two of which were novel. Three trajectories contributed 75% of COPD burden and were associated with modifiable early-life exposures whose impact was aggravated by adult factors. We postulate that reducing maternal smoking; encouraging immunization; and avoiding personal smoking, especially in those with smoking parents and/or low childhood lung function, may minimize COPD risk. Clinicians and asthmatic patients should be made aware of the potential long-term implications of non-optimal asthma control for lung function trajectory throughout life, and this should be investigated in future intervention trials.