Persistent Airflow Limitation in Asthma: Clinical Characteristics, Risk Factors, and Long-term Outcomes from a Multicenter Cohort Study.

BACKGROUND

Persistent airflow limitation (PAL) is an increasingly recognized asthma phenotype, but its prevalence, determinants, and prognostic significance in real-world settings remain unclear. This study evaluated the clinical characteristics and long-term outcomes associated with PAL and its severity in asthma.

METHODS

Multicenter analysis of combined retrospective and prospective cohorts in South Korea. PAL was defined as post-bronchodilator FEV1/FVC <0.70; severity was graded by STaging of Airflow obstruction by Ratio classification (STAR stage). Outcomes included subsequent exacerbations and longitudinal lung function change.

RESULTS

Among 849 patients with asthma, 640 (75.4%) had PAL. PAL was associated with older age, male sex, lower body mass index, higher smoking intensity, lower FEV1, history of tuberculosis, and less frequent allergic rhinitis. Optimal predictors of PAL were FEV1 ≤83.7% predicted, age ≥63.5 years, and smoking intensity ≥9.5 pack-years. During follow-up, severe exacerbations occurred more frequently in the PAL group (13.0% vs 5.7%) with a 1.8-fold higher incidence (IRR 1.77, 95% CI 1.13-2.79). Risk increased with PAL severity, particularly at STAR stage 4 vs stage 0 (aHR 3.32, 95% CI 1.60-6.89). Longitudinally, annual FEV1 decline was slower in PAL than in non-PAL (-28.1 vs -42.5 mL/year, P = 0.028), but within PAL, STAR stage 4 showed relatively faster declines in both FEV1 and FVC.

CONCLUSION

PAL and its severity independently predict the risk of severe exacerbations and progressive lung function decline in asthma, underscoring PAL as a key marker of disease progression and a potential target for early intervention.