A Distinct Low Lung Function Trajectory from Childhood to the Fourth Decade of Life

Abstract

Rationale: Low maximally attained lung function increases the risk of chronic obstructive pulmonary disease irrespective of the subsequent rate of lung function decline.

Objectives: We aimed to determine if there were individuals with a distinct, persistently low lung function trajectory in the CRS (Tucson Children's Respiratory Study).

Methods: The CRS, an ongoing birth cohort study, enrolled 1,246 participants between 1980 and 1984. Latent class linear mixed effects modeling of the ratio of FEV1 to FVC was used to identify distinct lung function trajectories among participants with two or more spirometry measurements between ages 11 and 32 years.

Measurements and main results: Among 599 participants with 2,142 observations, a model with two distinct trajectories (a low trajectory [n = 56; 9.3%] and a normal trajectory) fit the data significantly better than a model with only one trajectory (P = 0.0007). As compared with those with a normal trajectory, participants with a persistently low trajectory were more likely to have a history of maternal asthma (20.0% vs. 9.9%; P = 0.02); early life lower respiratory illness caused by respiratory syncytial virus (41.2% vs. 21.4%; P = 0.001); and physician-diagnosed active asthma at age 32 years (43.9% vs. 16.2%; P < 0.001). Individuals with a persistently low trajectory also demonstrated lower lung function as measured by average maximal expiratory flow at functional residual capacity during infancy and at age 6 years.

Conclusions: A distinct group of individuals in a nonselected population demonstrates a persistently low lung function trajectory that may be partly established at birth and predisposes them to chronic obstructive pulmonary disease later in life.

Keywords: asthma; chronic obstructive pulmonary disease; epidemiology; respiratory function tests.

Figure 1.

Lung function growth over time expressed as percent of maximal predicted FEV₁ for individuals assigned to low lung function trajectory versus normal trajectory from preadolescence into the fourth decade of life. Among 599 participants with at least two spirometry measurements, 543 were assigned to a normal trajectory and 56 to a low trajectory using latent class analysis.