1118-P: The Association of Ankle-Brachial Index and BMI with Pulmonary Disease in Type 1 Diabetes

Concerns about PRISm

Trajectory and mortality of preserved ratio impaired spirometry: the Rotterdam Study.

RATIONALE: Preserved Ratio Impaired Spirometry (PRISm) is a heterogeneous condition linked to increased respiratory symptoms and elevated all-cause mortality. PRISm is characterized by a preserved FEV1/FVC ratio (≥70%) alongside a reduced FEV1 (<80% predicted), and its course is unstable, with some individuals reverting to normal lung function while others progress to chronic obstructive pulmonary disease (COPD). The long-term trajectory over decades and impact of PRISm have not been thoroughly assessed in the UK. Using data from a birth cohort study, we evaluated PRISm trajectories in ever-smokers over two decades and investigated its association with mortality. METHODS: We conducted a cohort analysis using data from the Medical Research Council National Survey of Health & Development, a birth cohort initiated in 1946. Participants underwent regular clinical assessments, including pulmonary function tests (PFTs) at ages 43, 53, and 63. Associations with mortality were assessed using multivariable Cox proportional hazards models, adjusted for sex, smoking history (pack years), asthma diagnosis, and severity of airflow obstruction (classified by Global Initiative for Chronic Obstructive Lung Disease (GOLD) criteria). Mortality data were obtained through linked national death registries as of May 2024. RESULTS: 2,238 ever-smokers underwent PFTs at age 43 (47% female): 75% had normal spirometry, 16% had PRISm, and 9% exhibited COPD. At age 53, 1,877 ever-smokers were tested (48% female): 72% had normal spirometry, 18% had PRISm, and 10% had COPD. PRISm at age 43 was associated with increased all-cause mortality (Hazard Ratio (HR) = 1.31, 95%CI = 1.04-1.6, p = 0.020) and respiratory-specific mortality (HR = 2.5, 95%CI = 1.32-4.7, p = 0.005). PRISm at age 53 also predicted higher all-cause mortality (HR = 1.45, 95%CI = 1.11-1.89, p = 0.006). PRISm was unstable over time; of 196 participants with PRISm at age 43 who underwent repeat testing at ages 53 and 63, PRISm persisted in 72 (37%) at age 53, while 18 (9%) progressed to COPD and 106 (54%) reverted to normal spirometry. By age 63, of the 72 with persistent PRISm at age 53, 56 (78%) remained in the PRISm group, 5 (7%) developed COPD, and 11 (15%) reverted to normal spirometry. CONCLUSIONS: PRISm is an unstable condition over time, with a significant proportion of individuals reverting to normal lung function over a 10-20 year period. However, PRISm is linked to increased mortality as early as 43 years of age, highlighting its prognostic importance in high-risk populations.

BackgroundDifferentiating preserved ratio impaired spirometry (PRISm) from chronic obstructive pulmonary disease (COPD) is challenging. Traditional biphasic CT scans are limited by radiation exposure, while single-inspiratory CT-based deep learning lacks interpretability. This study aimed to develop a single-inspiratory quantitative computed tomography (QCT) nomogram integrating parenchymal, airway, and vascular parameters to redefine imaging definition boundaries.MethodsThis retrospective study (approved by Ethics Committee YJ-NBEY-KY-2023-107-01) screened 1,265 patients from Ningbo No. 2 Hospital (January 2021–December 2023), yielding 658 eligible participants (Normal: 135, PRISm: 328, COPD: 195) based on predefined inclusion/exclusion criteria. Single-inspiratory CT metrics (parenchymal, airway, vascular) were quantified using the Aview® system. Four logistic regression models distinguished PRISm from normal and COPD group receiver operating characteristic-area under the curve (ROC-AUC) evaluated performance.ResultsProgressive deterioration in age (COPD: 73.3 vs. PRISm: 69.1 vs. Normal: 64.1 years), male predominance (84.6% COPD vs. 57.9% PRISm), pulmonary function (FEV1%, FEV1/FVC), and CT markers (Pi10: PRISm 3.65 vs. Normal 3.26, P < 0.001) were observed. PRISm showed reduced superficial vessel diameter (AVD9: 2.64 mm vs. Normal 2.95 mm, P < 0.001). Diagnostic models achieved AUCs up to 0.984 (PRISm vs. severe COPD) and 0.853 (PRISm vs. all COPD).ConclusionThe QCT nomogram robustly differentiates PRISm from COPD, highlighting reduced superficial vessel diameter as a key biomarker. This radiation-efficient approach enables early COPD stratification via interpretable structural-functional metrics.

Background: Preserved ratio impaired spirometry (PRISm) is defined as a FEV₁ of less than 80% predicted and a FEV₁/forced vital capacity (FVC) ratio of 0·70 or higher. Previous research has indicated that PRISm is associated with respiratory symptoms and is a precursor of chronic obstructive pulmonary disease (COPD). However, these findings are based on relatively small selective cohorts with short follow-up. We aimed to determine the prevalence, risk factors, clinical implications, and mortality of PRISm in a large adult general population. Methods: For this cohort analysis, we used data from the UKBiobank to assess PRISm prevalence, risk factors and associated symptoms, and associated comorbidities in a large adult population. Participants with spirometry deemed acceptable by an investigator (best measure FEV₁ and FVC values) at baseline were included. Participants were excluded if they did not have acceptable spirometry or were missing data on body-mass index or smoking status. Control spirometry was defined as a FEV₁ of 80% or more predicted and a FEV₁/FVC ratio of 0·70 or higher. Airflow obstruction was defined as a FEV₁/FVC ratio of less than 0·70. We used multivariable regression to determine risk factors for PRISm and associated comorbidities. Individuals who lived within close proximity to an assessment centre were invited for follow-up, with repeat spirometry. Only participants who had been included at baseline were examined in follow-up. This allowed for a longitudinal analysis of PRISm over time and risk factors for transition to airflow obstruction. We also did the survival analysis for a 12-year period. Findings: Participants were recruited by UK Biobank between Dec 19, 2006, and Oct 10, 2010. We included 351 874 UK Biobank participants (189 247 women and 162 627 men) in our study, with a median follow-up of 9·0 years (IQR 8·0–10·0). 38 639 (11·0%) of 351 874 participants had PRISm at baseline. After adjustment, PRISm was strongly associated with obesity (odds ratio [OR] 2·40 [2·26–2·55], p < 0·0001), current smoking (1·48 [1·36–1·62], p < 0·0001), and patient reported doctor-diagnosed asthma (1·76 [1·66–1·88], p < 0·0001). Other risk factors identified included female sex, being overweight, trunk fat mass, and trunk fat percentage. PRISm was strongly associated with symptoms and comorbidity including increased risk of breathlessness (adjusted OR 2·0 [95% CI 1·91–2·14], p < 0·0001) and cardiovascular disease (adjusted OR 1·71 [1·64–1·83], p < 0·0001 for heart attack). Longitudinal analysis showed that 241 (12·2%) of 1973 participants who had PRISm at baseline had transitioned to airflow obstruction consistent with COPD. PRISm was associated with increased all-cause mortality (adjusted hazard ratio 1·61 [95% CI 1·53–1·69], p < 0·0001) versus control participants. Interpretation: PRISm was associated with breathlessness, multimorbidity, and increased risk of death, which does not seem to be explained by smoking, obesity, or existing lung disease. Although for many patients PRISm is transient, it is important to understand which individuals are at risk of progressive lung function abnormalities. Further research into the genetic, structural and functional pathophysiology of PRISm is warranted. Funding: UK Medical Research Council and University of Bristol.

Rationale: Preserved Ratio Impaired Spirometry (PRISm) is a condition defined by an FEV1 &amp;lt; 80% predicted and FEV1/FVC ratio ≥ 0.7. While specific driver mutations, such as EGFR and ALK1,2, are well-documented in lung adenocarcinoma patients with chronic obstructive pulmonary disease (COPD), the mutation profile in PRISm patients remains underexplored in current medical literature. This study aimed to investigate the distribution and clinical implications of driver mutations in lung adenocarcinoma patients across different lung function groups, including PRISm, COPD, and normal lung function. Methods: A retrospective analysis was conducted of 147 adenocarcinoma patients treated in the Mount Sinai Health System from January 2018 to May 2024. Patients were categorized by lung function (normal, COPD, PRISm). We compared the prevalence of driver mutations (ALK, BRAF, EGFR, HER2, MET, KRAS, NRAS, PIK3C, RET, ROS1, TP53), emphysema, PD-L1 levels, ECOG performance, cancer stage, and metastases in patients with normal lung function, PRISm and COPD. Statistical analyses used Kruskal-Wallis and Chi-Square tests, with significance at p &amp;lt; 0.05. Results: COPD patients had a significantly higher prevalence of emphysema (p = 0.0005) and lower ECOG scores, indicating poorer functional status compared to PRISm and normal groups (p = 0.015). Cancer stages III and IV were more common in PRISm and COPD groups than in the normal group (p = 0.023). PRISm patients had a significantly higher metastatic burden (p = 0.036). PD-L1 expression was not statistically significant across groups, and no significant differences were found for driver mutations between patients with normal lung function, PRISm and COPD. Discussion: The findings reveal distinct profiles for lung adenocarcinoma patients based on lung function. PRISm and COPD patients had higher metastatic burden and more advanced cancer stages than patients with normal lung function, suggesting a more aggressive disease course. Higher emphysema prevalence and lower ECOG scores in COPD demonstrate how COPD phenotype can affect functional status. Although driver mutations did not vary significantly between patients with normal lung function, PRISm and COPD, lung function stratification may be valuable in guiding treatment. Conclusion: PRISm and COPD adenocarcinoma patients have a more aggressive disease profile compared to those with normal lung function, marked by greater metastatic burden and advanced stage of lung cancer. Lung cancer screening should be therefore emphasized in PRISm patients who meet lung canceer screening eligibility. Increased emphysema prevalence in lung cancer and its effect on ECOG performance may effect patient outcomes.

BackgroundPersistent chronic airway inflammation and progressive airflow limitation are typical features of chronic obstructive pulmonary disease (COPD). Emerging evidence indicates that small airway dysfunction (SAD) plays a critical role in driving the sustained pathological progression of COPD. Preserved ratio impaired spirometry (PRISm) represents a spirometric pattern characterized by a reduced forced expiratory volume in 1 second (FEV₁) despite a preserved ratio. Current evidence inadequately elucidates the pathophysiological role of SAD and its intricate interplay with PRISm and COPD progression. On the other hand, impulse oscillometry (IOS) can be used as a complementary tool to spirometry to detect SAD. Detection of SAD in patients with chronic respiratory symptoms could help in the diagnosis of PRISm and COPD when spirometry is not achievable.ObjectiveTo investigate the diagnostic value of IOS for identifying SAD in patients with chronic respiratory symptoms, PRISm and COPD.MethodsBetween September 2021 and July 2023, 552 symptomatic patients without known structural lung disease who underwent both spirometry and IOS on the same day in the outpatient clinic were evaluated. The correlations between spirometry and the IOS parameters, and the ROC curves of the IOS parameters for SAD patients and COPD patients were analyzed.ResultsAmong the 552 patients included in the study, 96 patients had COPD, 39 patients had PRISm, and 417 patients had chronic cough. Among 456 chronic cough patients with preserved ratio spirometry, the incidence of PRISm was 8.55%. Based on spirometry-defined SAD, the incidence of SAD in the PRISm population was 71.8%, which was significantly higher than the 9.35% of the non-PRISm population. With increasing COPD GOLD stage, the IOS parameters R5-R20, R5, Fres, and Ax increased, whereas the traditional lung function parameters and X5 decreased. R5-R20, X5, Fres, and AX of COPD GOLD stage 1 patients were not substantially different from those of PRISm patients. In PRISm patients, R5-R20, R5 and Fres were strongly correlated with FEF25%-75%. R5-R20, R5, X5, Fres and AX were significantly associated with FEV1, FEV1/FVC, FEV1% predicted, FEF50%, FEF75% and FEF25%-75% in COPD patients. Through ROC curve analysis, the cutoffs for identifying SAD in patients with chronic respiratory symptoms and PRISm patients were obtained, with R5-R20 values of 0.075 and 0.105 kPa/L/s, respectively. The values of R5 were 0.365 and 0.375 kPa/L/s, respectively. The Fres values are 16.31 Hz and 17.11 Hz, respectively. The cutoff for detecting COPD in all patients was 0.485 kPa/L/s for R5, 0.125 kPa/L/s for R5-R20, -0.155 kPa/L/s for X5, and 17.98 Hz for Fres. Fres had the highest AUC value for both SAD and COPD detection, and it detected COPD the most in all patients, with a prevalence of 24.1%. R5 detected SAD the most in patients with chronic respiratory symptoms, with a prevalence of 47.5%. With a prevalence of 71.8%, spirometry identified SAD in patients with PRISm the most frequently.ConclusionAlmost all IOS parameters Linked to the small airways were significantly different in the PRISm population compared with patients with chronic respiratory symptoms. SAD severity in PRISm patients is similar to that in GOLD stage 2 COPD patients. The IOS can assess the disease severity of COPD.

Prevalence, risk factors, and clinical implications of preserved ratio impaired spirometry: a UK Biobank cohort analysis

Impairment of pulmonary function was evaluated in chronic bronchitis patients with preserved ratio impaired spirometry (PRISm). We retrospectively collected clinical data from 157 chronic bronchitis (CB) and 186 chronic obstructive pulmonary disease (COPD) patients between October 2014 and September 2017. These patients were assigned to three groups: control (normal pulmonary function), PRISm (forced expiratory volume in 1 second [FEV1]/forced vital capacity [FVC] ≥ 0.7, FEV1 < 80% of predicted value), and COPD (FEV1/FVC <0.7) groups. Because small airway function was the main focus, in the COPD group, only patients in accordance with the Global Initiative for Chronic Obstructive Lung Disease (GOLD) grades 1 and 2 were included. Evaluation of pulmonary function (including impulse oscillometry) was performed and compared among these groups. Compared with the control group, the PRISm and COPD groups showed statistically significant differences in the predicted FEV1% (p < 0.001), maximal expiratory flow (MEF) 25% (p < 0.001), MEF50% (p < 0.001), maximal midexpiratory flow (MMEF) 25–75% (p < 0.001), residual volume (RV)/total lung capacity (TLC; p < 0.001), FVC% (p < 0.001), total respiratory resistance and proximal respiratory resistance (R5-R20; p < 0.001), respiratory system reactance at 5 Hz (X5; p < 0.001), resonant frequency (Fres; p < 0.001), and area of reactance (Ax; p < 0.001). However, the predicted FEV1% and RV/TLC were similar between the PRISm and COPD groups (p=0.992 and 0.122, respectively). PRISm is a nonspecific pattern of pulmonary function that indicates small airway dysfunction and may increase the risk of transformation to obstructive ventilation dysfunction. This trial is registered with ChiCTR-OCH-14004904.

BackgroundEarly diagnosing Chronic Obstructive Pulmonary Disease (COPD) is relatively difficult. Therefore, the concepts of preserved ratio impaired spirometry (PRISm) and small airway disease (SAD) were proposed to achieve early diagnosis for COPD. Besides, the occurrence of COPD is positively related to age. However, the relationship among COPD, PRISm, and SAD still requires clarification. Thus, we estimated the proportions and risk factors of COPD and PRISm in the positive screening participants, and searched the methods of early diagnosing COPD via the SAD indicators.MethodsA total of 53,641 residents aged more than 60 years old from Shaoxing City, Zhejiang Province, China, completed a series of screening projects. And 2327 of positive screening participants ultimately finished bronchodilator tests. The data were statistically analyzed to figure out the proportions and risk factors of COPD and PRISm, and the efficacy of early diagnosing COPD by the SAD indicators.ResultsTotally 2229 positive screening participants were included, the proportion of PRISm was 6.3% (141/2229), and of COPD was 78.2% (1743/2229). Statistical analyses showed that COPD patients were more likely to be smokers, males, and older. And COPD patients had higher questionnaire scores, meaning that they were more prone to have family history of respiratory diseases and more severe respiratory symptoms. Additionally, COPD patients had lower maximal mid-expiratory flow (MMEF) pred, forced expiratory flow (FEF) 75pred, and FEF50pred. And we found that male sex and presence of respiratory symptoms might lead to COPD and PRISm. Also, the methods of early diagnosing COPD through the SAD indicators might be acceptable.ConclusionThere is a close association between COPD and decreased small airway function (SAF) among the participants included. Age, smoking, male sex, worse SAF, and respiratory symptoms might cause the progressing from normal people to PRISm, then to COPD patients. Besides, the SAD indicators such as MMEFpred, FEF75pred, and FEF50pred were included in lung function tests and bronchodilator tests. Intriguingly, it was found that early diagnosing COPD via the SAD indicators might be feasible. In the future, early diagnosis for COPD requires further research.

Chronic Obstructive Pulmonary Disease (COPD) is a disease of the lungs characterized by chronic airflow obstruction. Individuals with preserved ratio impaired spirometry (PRISm) may be at risk for developing COPD. This study aimed to characterize PRISm and COPD patients in terms of their immune response and endocrine profile to identify differences extending beyond lung function. The participants performed the clinical assessment, pulmonary function test, and blood collection to determine serum hormone levels and concentrations of cytokine. Differences were observed in the nutritional status, lung function, and comorbidity. There were no differences in IL-6, IL-8, IL-10, IL-12, and TNF levels between PRISm and COPD groups. Both PRISm and COPD patients have lower dehydroepiandrosterone (DHEA) and dehydroepiandrosterone sulfate (DHEA-S) levels than controls. Correlation analysis of PRISm and COPD patients revealed positive correlations between serum levels of DHEA-S and DHEA, with forced expiratory volume in 1 second (FEV1) and forced vital capacity (FVC), which negatively correlated with IL-8 levels. The results indicated that despite differences in lung function parameters, the PRISm and COPD groups exhibited similarities in endocrine profile alterations. This study represents the first attempt to link endocrine with immune markers and lung function in individuals with PRISm.

BackgroundWe estimated the prevalence and mortality risks of preserved ratio impaired spirometry (PRISm) and chronic obstructive pulmonary disease (COPD) in the US adult population.MethodsWe linked three waves of pre-bronchodilator spirometry data from the US National Health and Nutritional Examination Survey (2007–2012) with the National Death Index. The analytic sample included adults ages 20 to 79 without missing data on age, sex, height, BMI, race/ethnicity, and smoking status. We defined COPD (GOLD 1, 2, and 3–4) and PRISm using FEV1/FVC cut points by the Global Initiative for Chronic Obstructive Lung Disease (GOLD). We compared the prevalence of GOLD stages and PRISm by covariates across the three waves. We estimated adjusted all-cause and cause-specific mortality risks by COPD stage and PRISm using all three waves combined.ResultsPrevalence of COPD and PRISm from 2007–2012 ranged from 13.1%-14.3% and 9.6%-10.2%, respectively. We found significant differences in prevalence by sex, age, smoking status, and race/ethnicity. Males had higher rates of COPD regardless of stage, while females had higher rates of PRISm. COPD prevalence increased with age, but not PRISm, which was highest among middle-aged individuals. Compared to current and never smokers, former smokers showed lower rates of PRISm but higher rates of GOLD 1. COPD prevalence was highest among non-Hispanic White individuals, and PRISm was notably higher among non-Hispanic Black individuals (range 31.4%-37.4%). We found associations between PRISm and all-cause mortality (hazard ratio [HR]: 2.3 95% CI: 1.9—2.9) and various cause-specific deaths (HR ranges: 2.0–5.3). We also found associations between GOLD 2 (HR: 2.1, 95% CI: 1.7–2.6) or higher (HR: 4.2, 95% CI: 2.7–6.5) and all-cause mortality. Cause-specific mortality risk varied within COPD stages but typically increased with higher GOLD stage.ConclusionsThe prevalence of COPD and PRISm remained stable from 2007–2012. Greater attention should be paid to the potential impacts of PRISm due to its higher prevalence in minority groups and its associations with mortality across various causes including cancer.

Preserved Ratio Impaired Spirometry and COPD Accelerate Frailty Progression: Evidence From a Prospective Cohort Study

Physician diagnosed COPD with normal spirometry (dnsCOPD) (sometimes labeled pre-COPD) and Preserved Ratio Impaired Spirometry (PRISm) has been studied in population-based cohorts, but not in physician diagnosed COPD (dCOPD) patients from routine clinical practice. The Swedish National Airway Register (SNAR) is a large nationwide register including data from dCOPD patients from over 1000 clinics across all regions of Sweden and is representative of the COPD care in Sweden. We aimed to identify and characterize patients with dnsCOPD, PRISm and spirometrically confirmed COPD (sCOPD) from dCOPD patients in SNAR, stratify them further according to symptoms and exacerbations risk using the Global Initiative for Chronic Obstructive Lung Disease (GOLD) A/B/E classification, and assess differences in risk for exacerbations, cause-specific hospitalisations and mortality. We enrolled patients aged ≥30 years with dCOPD in the SNAR from 1 January 2014 to 30 June 2022 with complete spirometry i.e., postbronchodilator values for both forced expiratory volume in 1 s (FEV1) and forced vital capacity (FVC) (index date). Patients with concomitant asthma were excluded. Patients were stratified into dnsCOPD (FEV1/FVC ≥0.7 and FEV1 ≥80% predicted), PRISm (FEV1/FVC ≥0.7 and FEV1 <80% predicted) and sCOPD (FEV1/FVC <0.7). Further substratification was based on GOLD A/B/E (A: COPD assessment test (CAT) score <10 points and <2 moderate, 0 severe exacerbations within 1 year before the index date, B: CAT-score ≥10 points and <2 moderate, 0 severe exacerbations, E: ≥2 moderate or ≥1 severe exacerbation(s)). Patients were followed until 31 November 2022. Competing risk regression was used to calculate subdistribution hazard ratios (SHR)s with 95% confidence intervals (CIs) for exacerbation, hospitalisation and mortality. Of 45,653 patients with dCOPD, 5.4% had dnsCOPD, 11.4% had PRISm and 83.3% had sCOPD. Smoking history was similar between groups (ever smoker: dnsCOPD: 79% PRISm: 82% sCOPD: 86%) and inhalation therapy was common in all groups (any inhaler: 75%, 80% and 80%, triple combination: 22%, 28% and 35%). Patients with PRISm had a high prevalence of obesity (dnsCOPD: 30%, PRISm: 43%, COPD: 22%), cardiovascular disease (dnsCOPD: 39%, PRISm: 48%, COPD: 41%) and diabetes (dnsCOPD: 10%, PRISm: 17%, COPD: 9%). Baseline GOLD group B or E were highly prevalent in dnsCOPD (B: 54%, E: 11%), PRISm (B: 59%, E: 14%), as well as in COPD (B: 54%, E: 17%). DnsCOPD and PRISm patients had lower risk of exacerbations (SHR 0.69, 95%CI 0.64-0.74 and 0.85, 95%CI 0.81-0.89), respiratory hospitalisation (0.40, 95%CI 0.34-0.46 and 0.68, 95%CI 0.62-0.73), and respiratory mortality (0.22, 95%CI 0.13-0.37 and 0.60, 95%CI 0.48-0.75) compared to sCOPD. Cardiovascular mortality was lower in dnsCOPD (0.41, 95%CI 0.19-0.86), but similar in PRISm (0.73, 95%CI 0.49-1.08) compared to sCOPD. The A/B/E classification was predictive for all outcomes in dnsCOPD and PRISm. DnsCOPD and PRISm group E patients had higher risks for all outcomes than sCOPD group A or B. DnsCOPD and PRISm are prevalent in a real-life cohort of patients with a physician diagnosis of COPD. These patients are symptomatic, might suffer from exacerbations and are commonly treated with inhaled therapy, equally to sCOPD. Patients with PRISm had a high prevalence of obesity, diabetes and cardiovascular disease. DnsCOPD and PRISm had generally lower overall risks of exacerbation or respiratory events, although PRISm patients showed similar cardiovascular risk to sCOPD. The A/B/E classification predicted future events, even in dnsCOPD and PRISm patients. This study is performed with support from The Swedish Heart-Lung Foundation (20200150) and the Swedish government and country council ALF grant (ALFGBG-824371).

Preserved ratio impaired spirometry (PRISm) is a heterogeneous disease entity. Limited data are available regarding its prevalence, clinical course, or prognosis. We aimed to evaluate the longitudinal clinical course of patients with PRISm compared with chronic obstructive pulmonary disease (COPD). A retrospective study enrolled PRISm and COPD patients who underwent chest computed tomography and longitudinal pulmonary function tests between January 2013 and December 2020. We compared the incidence of acute exacerbations and lung function changes between PRISm and COPD patients. Of the 623 patients, 40 and 583 had PRISm and COPD, respectively. Compared to COPD patients, PRISm patients were younger, more likely to be female and have a history of tuberculosis, and less likely to be smokers. They also had less severe comorbidities, lower forced vital capacity (FVC) and diffusing capacity of the lungs for carbon monoxide (DLCO). The clinical course was not significantly different between the PRISm and COPD patients in terms of the risk of moderate-to-severe acute exacerbations or proportion of frequent exacerbators. During follow-up, PRISm patients had a significantly slower annual decline of forced expiratory volume in 1 second, FVC, and DLCO than COPD patients. PRISm patients had no significant difference in the risk of acute exacerbations, but a significantly slower decline of lung function during longitudinal follow-up, compared with COPD patients.