[Comparison of lung function and inflammatory markers and analysis of risk factors for acute exacerbations in patients with chronic obstructive pulmonary disease and persistent airflow limitation asthma].

<b>Objective:</b> To analyze the differences in pulmonary function and inflammatory indicators between patients with chronic obstructive pulmonary disease (COPD) and those with persistent airflow limitation (PAL) asthma, and to explore the influencing factors of acute exacerbation in patients with COPD and PAL asthma. <b>Methods:</b> A total of 192 patients with stable COPD and PAL asthma who visited the Department of Respiratory and Critical Care Medicine of the Shanghai General Hospital of Shanghai Jiao Tong University School of Medicine from January 2021 to December 2022 were prospectively included. Among them, 143 were male and 49 were female; the age ranged from 40 to 87 years [(63.4±12.1) years]; 92 were in the COPD group and 100 were in the PAL asthma group. The differences in lung function and inflammatory markers between the COPD group and the PAL asthma group were compared. The disease exacerbation of COPD and PAL asthma patients was evaluated every 3 months. After 12 months of follow-up, 138 patients completed the acute exacerbation assessment, including 105 males and 33 females; the age was (64.9±10.2) years; 66 were in the COPD group and 72 were in the PAL asthma group. Multivariate logistic regression models were used to analyze the influencing factors of acute exacerbation in COPD and PAL asthma. <b>Results:</b> The percentage of predicted forced expiratory flow at 75% of forced vital capacity (FEF₇₅%Pred), the percentage of predicted mid-expiratory flow between 25% and 75% of forced vital capacity (FEF_25-75%Pred), and the neutrophil-to-lymphocyte ratio (NLR) in the PAL asthma group were all lower than those in the COPD group (all <i>P</i><0.05); the eosinophil count, lymphocyte count, fractional exhaled nitric oxide (FeNO), and the proportion of patients with type 2 inflammation were all higher in the PAL asthma group than in the COPD group (all <i>P</i><0.05). The improvement rates of forced expiratory volume in one second (ΔFEV₁%), forced vital capacity (ΔFVC%), forced expiratory flow at 50% of forced vital capacity (ΔFEF₅₀%), forced expiratory flow at 75% of forced vital capacity (ΔFEF₇₅%), and mid-expiratory flow between 25% and 75% of forced vital capacity (ΔFEF_25-75%) in the COPD group were all lower than those in the PAL asthma group (all <i>P</i><0.05). There were 22 cases (33.3%) of acute exacerbation in the COPD group. There were 25 cases (34.7%) of acute attack in the PAL asthma group. A lower baseline FEV₁%Pred (<i>OR</i>=0.934, 95%<i>CI</i>: 0.892-0.979) and a higher NLR (<i>OR</i>=1.185, 95%<i>CI</i>: 1.003-1.400) were risk factors for acute exacerbation in COPD patients within one year; a lower baseline FEV₁%Pred (<i>OR</i>=0.896, 95%<i>CI</i>: 0.823-0.976), higher ΔFEF₇₅% (<i>OR</i>=1.038, 95%<i>CI</i>: 1.011-1.066), and type 2 inflammation (<i>OR</i>=7.534, 95%<i>CI</i>: 1.254-45.246) were risk factors for acute attacks in PAL asthma patients within one year. <b>Conclusions:</b> Patients with PAL asthma have more prominent type 2 inflammation features and stronger reversibility of small airways. Lower FEV₁%Pred and higher NLR are risk factors for acute exacerbation in COPD patients, while lower FEV₁%Pred, higher ΔFEF₇₅%Pred and type 2 inflammation are risk factors for acute attacks in PAL asthma patients.