Risk factors of acute exacerbation and disease progression in young patients with COPD.

Objective: We aimed to elucidate the clinical factors associated with acute exacerbation and disease progression in young patients with chronic obstructive pulmonary disease (COPD).

Methods: This retrospective longitudinal observational study included patients with COPD aged between 20 and 50 years with post-bronchodilator forced expiratory volume in one second (FEV₁)/forced vital capacity (FVC)<0.7. Eligible patients were followed up with ≥2 spirometry examinations at 1 year interval after COPD diagnosis. The primary outcome was moderate-to-severe acute exacerbation in young patients with COPD. Secondary outcomes were early initiation of regular inhalation therapy and accelerated annual post-bronchodilator FEV₁ decline.

Results: A total of 342 patients were followed up during a median of 64 months. In multivariable analyses, risk factors for moderate-to-severe exacerbation were history of asthma (adjusted HR (aHR)=2.999, 95% CI=[2.074-4.335]), emphysema (aHR=1.951, 95% CI=[1.331-2.960]), blood eosinophil count >300/µL (aHR=1.469, 95% CI=[1.038-2.081]) and low FEV₁ (%) (aHR=0.979, 95% CI=[0.970-0.987]). A history of asthma, sputum, blood eosinophil count >300/µL, low FEV₁ (%) and low diffusing capacity of the lung for carbon monoxide (DL_CO) (%) were identified as clinical factors associated with the early initiation of regular inhalation therapy. The risk factors associated with worsened FEV₁ decline were increasing age, female sex, history of pulmonary tuberculosis, sputum, low FEV₁ (%) and low DL_CO (%).

Conclusions: In young COPD patients, specific high-risk features of acute exacerbation and disease progression need to be identified, including a history of previous respiratory diseases, current respiratory symptoms, blood eosinophil counts, and structural or functional pulmonary impairment.