Rationale: The determinants and health outcomes of lung function trajectories of older adults in the general population are poorly understood.

Objectives: To investigate the prevalence, characteristics, and clinical relevance of lung function trajectories in adults aged 45 years and older.

Methods: Data-driven k-means clustering was applied to baseline and annualized change in FEV₁ and FVC z-scores in participants of the Rotterdam Study, a prospective population-based cohort study, with repeated spirometry (n=3,884; baseline age: mean=64.7 (SD=8.9) years). The relationship between lung function trajectory clusters and all-cause mortality and the incidence of respiratory symptoms, COPD (FEV₁/FVC<0.7 without asthma), preserved ratio impaired spirometry (PRISm; FEV₁/FVC?0.7 and FEV₁ or FVC<80%), and frailty was evaluated.

Results: Six trajectory clusters were identified, with the reference group being high baseline spirometry+normal lung function decline (32.3%). Low baseline+rapid decline (3.5%) was independently associated with baseline current smoking, more pack-years, higher serum C-reactive protein levels and diuretic use. Two clusters were at an increased risk for all-cause mortality: low baseline+normal decline (prevalence: 30.2%; HR=1.82 (95%CI: 1.41-2.35), p<0.001) and low baseline+rapid decline (3.05 (2.05- 4.54), p<0.001), with the latter cluster also showing the highest incidence of symptoms, COPD, PRISm, and frailty from robust status. In contrast, low baseline+attenuated decline (17.5%) had no increased mortality nor COPD incidence.

Conclusion: This study reveals clinically relevant lung function trajectory clusters in middle-aged and older adults in the general population.