Distinctive lung function trajectories from age 10 to 26 years in men and women and associated early life risk factors - a birth cohort study.

Pre-bronchodilator lung function including forced vital capacity (FVC), forced expiratory flow in 1 second (FEV ₁ ), their ratio (FEV ₁ /FVC), and forced expiratory flow 25-75% (FEF _25-75 ) measured at age 10, 18, and 26 years in the Isle of Wight birth cohort was analyzed for developmental patterns (trajectories). Early life risk factors before the age of 10 years were assessed for the trajectories.
Method: Members of the birth cohort (1989/90) were followed at age 1, 2, 4, 10, 18, and 26 years. Allergic sensitization and questionnaire data were collected. Spirometry tests were performed and evaluated according to the American Thoracic Society (ATS) criteria at 10, 18, and 26 years. To identify developmental trajectories for FVC, FEV ₁ , FEV ₁ /FVC, and FEF _25-75 from 10 to 26 years, a finite mixture model was applied to the longitudinal lung function data, separately for males and females. Associations of early life factors with the respective lung function trajectories were assessed using log-linear and logistic regression analyses.
Results: Both high and low lung function trajectories were observed in men and women. FVC continued to grow beyond 18 years in men and women, whereas FEV ₁ peaked at age 18 years in female trajectories and in one male trajectory. For the FEV ₁ /FVC ratios and FEF _25-75 most trajectories appeared highest at age 18 and declined thereafter. However, the low FEV ₁ /FVC trajectory in both sexes showed an early decline at 10 years. Lower birth weight was linked with lower lung function trajectories in males and females. Eczema in the first year of life was a risk factor for later lung function deficits in females, whereas the occurrence of asthma at 4 years of age was a risk factor for later lung function deficits in males. A positive skin prick test at age four was a risk for the low FEV ₁ trajectory in females and for the low FEV ₁ /FVC trajectory in males.
Conclusion: Men and women showed distinctive lung function trajectories and associated risk factors. Lower lung function trajectories can be explained by not achieving maximally attainable function at age 18 years and by a function decline from 18 to 26 years.