Abstract
Rationale: Spirometry is essential for diagnosis and assessment of prognosis in patients with chronic obstructive pulmonary disease (COPD). Objectives: To identify FEV(1) trajectories and their determinants on the basis of annual spirometry measurements among individuals with and without airway obstruction (AO) and to assess mortality in relation to trajectories. Methods: From 2002 through 2004, individuals with AO (FEV(1)/VC < 0.70, n = 993) and age- and sex-matched nonobstructive (NO) referents were recruited from population-based cohorts. Annual spirometry until 2014 was used in joint-survival latent-class mixed models to identify lung function trajectories. Mortality data were collected during 15 years of follow-up. Measurements and Main Results: Three trajectories were identified among the subjects with AO and two among the NO referents. Trajectory membership was driven by baseline FEV(1)% predicted (FEV(1)%pred) in both groups and also by pack-years in subjects with AO and current smoking in NO referents. Longitudinal FEV(1)%pred depended on baseline FEV(1)%pred, pack-years, and obesity. The trajectories were distributed as follows: among individuals with AO, 79.6% in AO trajectory 1 (FEV(1) high with normal decline), 12.8% in AO trajectory 2 (FEV(1) high with rapid decline), and 7.7% in AO trajectory 3 (FEV(1) low with normal decline) (mean, 27, 72, and 26 ml/yr, respectively) and, among NO referents, 96.7% in NO trajectory 1 (FEV(1) high with normal decline) and 3.3% in NO trajectory 2 (FEV(1) high with rapid decline) (mean, 34 and 173 ml/yr, respectively). Hazard for death was increased for AO trajectories 2 (hazard ratio [HR], 1.56) and 3 (HR, 3.45) versus AO trajectory 1 and for NO trajectory 2 (HR, 2.99) versus NO trajectory 1. Conclusions: Three different FEV(1) trajectories were identified among subjects with AO and two among NO referents, with different outcomes in terms of FEV(1) decline and mortality. The FEV(1) trajectories among subjects with AO and the relationship between low FVC and trajectory outcome are of particular clinical interest.