Background: Ambient air pollution can contribute to the development and exacerbation of COPD. However, the influence of air pollution on objective COPD phenotypes, especially from imaging, is not well studied. We investigated the influence of long-term exposure to air pollution on lung function and quantitative imaging measurements in a Korean cohort of participants with and without COPD diagnosis. Methods: Study participants (N = 457 including 296 COPD cases) were obtained from the COPD in Dusty Areas (CODA) cohort. Annual average concentrations of particulate matter less than or equal to 10 μm in diameter (PM₁₀) and nitrogen dioxide (NO₂) were estimated at the participants’ residential addresses using a spatial air pollution prediction model. All the participants underwent volumetric computerized tomography (CT) and spirometry measurements and completed survey questionnaires. We examined the associations of PM₁₀ and NO₂ with FVC, FEV₁, emphysema index, and wall area percent, using linear regression models adjusting for age, gender, education, smoking, height, weight, and COPD medication. Results: The age of study participants averaged 71.7 years. An interquartile range difference in annual PM₁₀ exposure of 4.4 μg/m³ was associated with 0.13 L lower FVC (95% confidence interval (CI), − 0.22- -0.05, p = 0.003). Emphysema index (mean = 6.36) was higher by 1.13 (95% CI, 0.25–2.02, p = 0.012) and wall area percent (mean = 68.8) was higher by 1.04 (95% CI, 0.27–1.80, p = 0.008). Associations with imaging phenotypes were not observed with NO₂. Conclusions: Long-term exposure to PM₁₀ correlated with both lung function and COPD-relevant imaging phenotypes in a Korean cohort.

To date, more than 125 species of nontuberculous mycobacteria (NTM) have been identified. In this study, we investigated the frequency and clinical implication of the rarely isolated NTM from respiratory specimens. Patients with NTM isolated from their respiratory specimens between July 1, 2010 and June 31, 2012 were screened for inclusion. Rare NTM were defined as those NTM not falling within the group of eight NTM species commonly identified at our institution: Mycobacterium avium, M. intracellulare, M. abscessus, M. massiliense, M. fortuitum, M. kansasii, M. gordonae, and M. peregrinum. Clinical, radiographic and microbiological data from patients with rare NTM were reviewed and analyzed. During the study period, 73 rare NTM were isolated from the respiratory specimens of 68 patients. Among these, M. conceptionense was the most common (nine patients, 12.3%). The median age of the 68 patients with rare NTM was 68 years, while 39 of the patients were male. Rare NTM were isolated only once in majority of patient (64 patients, 94.1%). Among the four patients from whom rare NTM were isolated two or more times, only two showed radiographic aggravation caused by rare NTM during the follow-up period. Most of the rarely identified NTM species were isolated from respiratory specimens only once per patient, without concomitant clinical aggravation. Clinicians could therefore observe such patients closely without invasive work-ups or treatment, provided the patients do not have decreased host immunity towards mycobacteria.

The frequency and clinical manifestation of lung fibrosis accompanied by coronavirus disease (COVID-19) are not well-established. We aimed to identify the factors attributed to post-COVID-19 fibrosis. This single-center prospective study included patients diagnosed with COVID-19 pneumonia from 12 April to 22 October 2021 in the Republic of Korea. The primary outcome was the presence of pulmonary fibrosis on a CT scan 3 months after discharge; the fibrosis risk was estimated by a multiple logistic regression. The mean patient age was 55.03 ± 12.32 (range 27–85) years; 65 (66.3%) were men and 33 (33.7%) were women. The age, Charlson Comorbidity Index, lactate dehydrogenase level, aspartate aminotransferase level, and Krebs von den Lungen-6 level were significantly higher and the albumin level and the saturation of the peripheral oxygen/fraction of inspired oxygen (SpO₂/FiO₂) ratio were significantly lower in the fibrosis group than in the non-fibrosis group; the need for initial oxygen support was also greater in the fibrosis group. An older age (adjusted odds ratio (AOR) 1.12; 95% confidence interval (CI) 1.03–1.21) and a lower initial SpO₂/FiO₂ ratio (AOR 7.17; 95% CI 1.72–29.91) were significant independent risk factors for pulmonary fibrosis after COVID-19 pneumonia. An older age and a low initial SpO₂/FiO₂ ratio were crucial in predicting pulmonary fibrosis after COVID-19 pneumonia.

Backgrounds The management of lung complications, especially fibrosis, after COVID-19 pneumonia, is an important issue in the COVID-19 post-pandemic era. We aimed to investigate risk factors for pulmonary fibrosis development in patients with severe COVID-19 pneumonia. Methods Clinical and radiological data were prospectively collected from 64 patients who required mechanical ventilation due to COVID-19 pneumonia and were enrolled from eight hospitals in South Korea. Fibrotic changes on chest CT were evaluated by visual assessment, and extent of fibrosis (mixed disease score) was measured using automatic quantification system. Results 64 patients were enrolled, and their mean age was 58.2 years (64.1% were males). On chest CT (median interval: 60 days [IQR; 41–78 days] from enrolment), 35 (54.7%) patients showed ≥3 fibrotic lesions. The most frequent fibrotic change was traction bronchiectasis (47 patients, 73.4 %). Median extent of fibrosis measured by automatic quantification was 10.6% (IQR, 3.8–40.7%). In a multivariable Cox proportional hazard model, which included nine variables with a p value of <0.10 in an unadjusted analysis as well as age, sex and Body Mass Index, male sex (HR, 3.01; 95% CI, 1.27 to 7.11) and higher initial Sequential Organ Failure Assessment (SOFA) score (HR, 1.18; 95% CI, 1.02 to 1.37) were independently associated with pulmonary fibrosis (≥3 fibrotic lesions). Conclusion Our data suggests that male gender and higher SOFA score at intensive care unit admission were associated with pulmonary fibrosis in patients with severe COVID-19 pneumonia requiring mechanical ventilation.

Background: Evidence regarding the timing of the application of mechanical ventilation among patients with severe coronavirus disease (COVID-19) is insufficient. This systematic review and meta-analysis aimed to evaluate the effectiveness of early intubation compared to late intubation in patients with severe and critical COVID-19. Methods: For this study, we searched the MEDLINE, EMBASE, and Cochrane databases as well as one Korean domestic database on July 15, 2021. We updated the search monthly from September 10, 2021 to February 10, 2022. Studies that compared early intubation with late intubation in patients with severe COVID-19 were eligible for inclusion. Relative risk (RR) and mean difference (MD) were calculated as measures of effect using the random-effects model for the pooled estimates of in-hospital mortality, intensive care unit (ICU) length of stay (LOS), duration of mechanical ventilation (MV), hospital LOS, ICU-free days, and ventilator-free days. Subgroup analysis was performed based on the definition of early intubation and the index time. To assess the risk of bias in the included studies, we used the Risk of Bias Assessment tool for Non-randomized studies 2.0. Results: Of the 1523 records identified, 12 cohort studies, involving 2843 patients with severe COVID-19 were eligible. There were no differences in in-hospital mortality (8 studies, n = 795; RR 0.91, 95% CI 0.75–1.10, P = 0.32, I² = 33%), LOS in the ICU (9 studies, n = 978; MD −1.77 days, 95% CI −4.61 to 1.07 days, P = 0.22, I² = 78%), MV duration (9 studies, n = 1,066; MD −0.03 day, 95% CI −1.79 to 1.72 days, P = 0.97, I² = 49%), ICU-free days (1 study, n = 32; 0 day vs. 0 day; P = 0.39), and ventilator-free days (4 studies, n = 344; MD 0.94 day, 95% CI −4.56 to 6.43 days, P = 0.74, I² = 54%) between the early and late intubation groups. However, the early intubation group had significant advantage in terms of hospital LOS (6 studies, n = 738; MD −4.32 days, 95% CI −7.20 to −1.44 days, P = 0.003, I² = 45%). Conclusion: This study showed no significant difference in both primary and secondary outcomes between the early intubation and late intubation groups. Trial registration This study was registered in the Prospective Register of Systematic Reviews on 16 February, 2022 (registration number CRD42022311122).

It is unclear whether various bronchodilator reversibility (BDR) criteria affect the prognosis of chronic obstructive pulmonary disease (COPD). The aim of this study is to evaluate the impact of positive BDR defined according to various BDR criteria on the risk of severe acute exacerbation (AE) in COPD patients. Patients from four prospective COPD cohorts in South Korea who underwent follow-up for at least 1 year were enrolled in this study. The assessed BDR criteria included the Global Initiative for Chronic Obstructive Lung Disease (GOLD), American Thoracic Society (ATS), American College of Chest Physicians, (ACCP), major criteria of the Spanish definition of asthma-COPD overlap syndrome (ACOS), criteria compatible with ACOS in the Global Initiative for Asthma (GINA), and European Respiratory Society (ERS). The rate of patients with severe AE who required hospitalization within 1 year due to BDR results according to each set of criteria was analyzed using logistic regression models. Among a total of 854 patients, the BDR-positive cases varied according to the criteria used. There was a 3.5% positive BDR rate according to GINA and a 29.9% rate according to the ATS criteria. Positive BDR according to the GOLD criteria was significantly associated with a decreased risk of severe AE (adjusted odds ratio (aOR) = 0.38; 95% Confidence interval (CI) = 0.15–0.93). This result remained statistically significant even in a sensitivity analysis that included only participants with a smoking history of at least 10 pack-years and in the analysis for the propensity score-matched participants. Among different criteria for positive BDR, the use of the GOLD ones was significantly associated with a decreased risk of severe AE in COPD patients. Increase use of ICS/LABA may have affected this relationship.