Background/Aims: Chronic obstructive pulmonary disease (COPD) management guidelines have increasingly emphasised the importance of exacerbation prevention, and the role of blood eosinophil count (BEC) as a biomarker for inhaled corticosteroids (ICS) response. This study aimed to describe the distribution and stability of BEC and understand real-world treatment patterns among COPD patients in South Korea. Methods: This was a retrospective database analysis using data obtained from the KOrea COPD Subgroup Study (KOCOSS) registry between January 2012 and August 2018. KOCOSS is an ongoing, longitudinal, prospective, multi-centre, non-interventional study investigating early COPD amongst South Korean patients. BEC stability was assessed by calculating the intra-class correlation (ICC) coefficient. “Exacerbators” were patients who had a record of ≥ 1 exacerbation in the 12 months prior to the visit. Results: The study included 2,661 patients with a mean age of 68.6 years. Most patients were male (92.0%). Mean BEC was significantly higher in exacerbators compared to non-exacerbators. Patients with ≥ 2 exacerbations at baseline had a less stable BEC over time (ICC = 0.44) compared to non-exacerbators (ICC = 0.57). Patients with BEC ≥ 300 cells/μL at baseline predominantly received triple therapy (43.8%). Conclusions This study may further develop current understanding on BEC profiles amongst COPD patients in South Korea. BEC measurements are stable and reproducible among COPD patients, which supports its use as a potential biomarker.

Background/Aims: Chronic obstructive pulmonary disease (COPD) management guidelines have increasingly emphasised the importance of exacerbation prevention, and the role of blood eosinophil count (BEC) as a biomarker for inhaled corticosteroids (ICS) response. This study aimed to describe the distribution and stability of BEC and understand real-world treatment patterns among COPD patients in South Korea. Methods: This was a retrospective database analysis using data obtained from the KOrea COPD Subgroup Study (KOCOSS) registry between January 2012 and August 2018. KOCOSS is an ongoing, longitudinal, prospective, multi-centre, non-interventional study investigating early COPD amongst South Korean patients. BEC stability was assessed by calculating the intra-class correlation (ICC) coefficient. “Exacerbators” were patients who had a record of ≥ 1 exacerbation in the 12 months prior to the visit. Results: The study included 2,661 patients with a mean age of 68.6 years. Most patients were male (92.0%). Mean BEC was significantly higher in exacerbators compared to non-exacerbators. Patients with ≥ 2 exacerbations at baseline had a less stable BEC over time (ICC = 0.44) compared to non-exacerbators (ICC = 0.57). Patients with BEC ≥ 300 cells/μL at baseline predominantly received triple therapy (43.8%). Conclusions This study may further develop current understanding on BEC profiles amongst COPD patients in South Korea. BEC measurements are stable and reproducible among COPD patients, which supports its use as a potential biomarker.

Background/Aims: Chronic obstructive pulmonary disease (COPD) management guidelines have increasingly emphasised the importance of exacerbation prevention, and the role of blood eosinophil count (BEC) as a biomarker for inhaled corticosteroids (ICS) response. This study aimed to describe the distribution and stability of BEC and understand real-world treatment patterns among COPD patients in South Korea. Methods: This was a retrospective database analysis using data obtained from the KOrea COPD Subgroup Study (KOCOSS) registry between January 2012 and August 2018. KOCOSS is an ongoing, longitudinal, prospective, multi-centre, non-interventional study investigating early COPD amongst South Korean patients. BEC stability was assessed by calculating the intra-class correlation (ICC) coefficient. “Exacerbators” were patients who had a record of ≥ 1 exacerbation in the 12 months prior to the visit. Results: The study included 2,661 patients with a mean age of 68.6 years. Most patients were male (92.0%). Mean BEC was significantly higher in exacerbators compared to non-exacerbators. Patients with ≥ 2 exacerbations at baseline had a less stable BEC over time (ICC = 0.44) compared to non-exacerbators (ICC = 0.57). Patients with BEC ≥ 300 cells/μL at baseline predominantly received triple therapy (43.8%). Conclusions This study may further develop current understanding on BEC profiles amongst COPD patients in South Korea. BEC measurements are stable and reproducible among COPD patients, which supports its use as a potential biomarker.

Background: The diagnosis of tuberculous pleural effusion (TPE) often relies on pleural fluid adenosine deaminase (ADA) levels. The diagnostic utility of ADA, however, is influenced by the prevalence of tuberculosis (TB) in local populations. Malignant pleural effusion (MPE) cases can exhibit moderately elevated ADA levels comparable to those seen in TPE. As population aging potentially impacts ADA levels, global TB incidence is decreasing whereas the burden of malignancy is on the rise. Consequently, epidemiological shifts and temporal changes in ADA distribution complicate the differential diagnosis between TPE and MPE when ADA levels are within the 40–70 IU/L range. Nonetheless, data specific to this subset are scarce. Methods: This retrospective study included consecutive patients aged > 18 years with confirmed TPE and MPE, spanning from 2012 to 2023. ADA levels in pleural fluid were categorized into three groups: < 40 IU/L, 40–70 IU/L, and > 70 IU/L. The study examined annual trends in the frequency of new cases and ADA level distributions over time and identified discriminating factors between TPE and MPE in cases with ADA levels of 40–70 IU/L. Results: In total, 297 TPE and 369 MPE cases were included in this study. Over the study period, the frequency of TPE progressively declined, while that of MPE increased. In the most recent four-year period, new TPE and MPE cases with ADA levels of 40–70 IU/L occurred at comparable numbers. Multivariable analysis identified pleural fluid carcinoembryonic antigen (CEA) levels and the number of focal pleural nodules as independent predictors for MPE. Specifically, the presence of either CEA levels > 15.7 ng/mL or more than eight pleural nodules yielded the highest diagnostic accuracy with a sensitivity of 88%, specificity of 100%, and an area under the curve of 0.95. Conclusion The differential diagnosis between TPE and MPE with pleural ADA levels of 40–70 IU/L has become increasingly critical due to evolving epidemiological patterns and ADA distribution changes over time. Pleural fluid CEA levels and the characteristics of pleural nodules may offer valuable guidance in distinguishing between TPE and MPE within this diagnostic gray zone.

Background: The diagnosis of tuberculous pleural effusion (TPE) often relies on pleural fluid adenosine deaminase (ADA) levels. The diagnostic utility of ADA, however, is influenced by the prevalence of tuberculosis (TB) in local populations. Malignant pleural effusion (MPE) cases can exhibit moderately elevated ADA levels comparable to those seen in TPE. As population aging potentially impacts ADA levels, global TB incidence is decreasing whereas the burden of malignancy is on the rise. Consequently, epidemiological shifts and temporal changes in ADA distribution complicate the differential diagnosis between TPE and MPE when ADA levels are within the 40–70 IU/L range. Nonetheless, data specific to this subset are scarce. Methods: This retrospective study included consecutive patients aged > 18 years with confirmed TPE and MPE, spanning from 2012 to 2023. ADA levels in pleural fluid were categorized into three groups: < 40 IU/L, 40–70 IU/L, and > 70 IU/L. The study examined annual trends in the frequency of new cases and ADA level distributions over time and identified discriminating factors between TPE and MPE in cases with ADA levels of 40–70 IU/L. Results: In total, 297 TPE and 369 MPE cases were included in this study. Over the study period, the frequency of TPE progressively declined, while that of MPE increased. In the most recent four-year period, new TPE and MPE cases with ADA levels of 40–70 IU/L occurred at comparable numbers. Multivariable analysis identified pleural fluid carcinoembryonic antigen (CEA) levels and the number of focal pleural nodules as independent predictors for MPE. Specifically, the presence of either CEA levels > 15.7 ng/mL or more than eight pleural nodules yielded the highest diagnostic accuracy with a sensitivity of 88%, specificity of 100%, and an area under the curve of 0.95. Conclusion The differential diagnosis between TPE and MPE with pleural ADA levels of 40–70 IU/L has become increasingly critical due to evolving epidemiological patterns and ADA distribution changes over time. Pleural fluid CEA levels and the characteristics of pleural nodules may offer valuable guidance in distinguishing between TPE and MPE within this diagnostic gray zone.

Background: The diagnosis of tuberculous pleural effusion (TPE) often relies on pleural fluid adenosine deaminase (ADA) levels. The diagnostic utility of ADA, however, is influenced by the prevalence of tuberculosis (TB) in local populations. Malignant pleural effusion (MPE) cases can exhibit moderately elevated ADA levels comparable to those seen in TPE. As population aging potentially impacts ADA levels, global TB incidence is decreasing whereas the burden of malignancy is on the rise. Consequently, epidemiological shifts and temporal changes in ADA distribution complicate the differential diagnosis between TPE and MPE when ADA levels are within the 40–70 IU/L range. Nonetheless, data specific to this subset are scarce. Methods: This retrospective study included consecutive patients aged > 18 years with confirmed TPE and MPE, spanning from 2012 to 2023. ADA levels in pleural fluid were categorized into three groups: < 40 IU/L, 40–70 IU/L, and > 70 IU/L. The study examined annual trends in the frequency of new cases and ADA level distributions over time and identified discriminating factors between TPE and MPE in cases with ADA levels of 40–70 IU/L. Results: In total, 297 TPE and 369 MPE cases were included in this study. Over the study period, the frequency of TPE progressively declined, while that of MPE increased. In the most recent four-year period, new TPE and MPE cases with ADA levels of 40–70 IU/L occurred at comparable numbers. Multivariable analysis identified pleural fluid carcinoembryonic antigen (CEA) levels and the number of focal pleural nodules as independent predictors for MPE. Specifically, the presence of either CEA levels > 15.7 ng/mL or more than eight pleural nodules yielded the highest diagnostic accuracy with a sensitivity of 88%, specificity of 100%, and an area under the curve of 0.95. Conclusion The differential diagnosis between TPE and MPE with pleural ADA levels of 40–70 IU/L has become increasingly critical due to evolving epidemiological patterns and ADA distribution changes over time. Pleural fluid CEA levels and the characteristics of pleural nodules may offer valuable guidance in distinguishing between TPE and MPE within this diagnostic gray zone.

Background: The diagnosis of tuberculous pleural effusion (TPE) often relies on pleural fluid adenosine deaminase (ADA) levels. The diagnostic utility of ADA, however, is influenced by the prevalence of tuberculosis (TB) in local populations. Malignant pleural effusion (MPE) cases can exhibit moderately elevated ADA levels comparable to those seen in TPE. As population aging potentially impacts ADA levels, global TB incidence is decreasing whereas the burden of malignancy is on the rise. Consequently, epidemiological shifts and temporal changes in ADA distribution complicate the differential diagnosis between TPE and MPE when ADA levels are within the 40–70 IU/L range. Nonetheless, data specific to this subset are scarce. Methods: This retrospective study included consecutive patients aged > 18 years with confirmed TPE and MPE, spanning from 2012 to 2023. ADA levels in pleural fluid were categorized into three groups: < 40 IU/L, 40–70 IU/L, and > 70 IU/L. The study examined annual trends in the frequency of new cases and ADA level distributions over time and identified discriminating factors between TPE and MPE in cases with ADA levels of 40–70 IU/L. Results: In total, 297 TPE and 369 MPE cases were included in this study. Over the study period, the frequency of TPE progressively declined, while that of MPE increased. In the most recent four-year period, new TPE and MPE cases with ADA levels of 40–70 IU/L occurred at comparable numbers. Multivariable analysis identified pleural fluid carcinoembryonic antigen (CEA) levels and the number of focal pleural nodules as independent predictors for MPE. Specifically, the presence of either CEA levels > 15.7 ng/mL or more than eight pleural nodules yielded the highest diagnostic accuracy with a sensitivity of 88%, specificity of 100%, and an area under the curve of 0.95. Conclusion The differential diagnosis between TPE and MPE with pleural ADA levels of 40–70 IU/L has become increasingly critical due to evolving epidemiological patterns and ADA distribution changes over time. Pleural fluid CEA levels and the characteristics of pleural nodules may offer valuable guidance in distinguishing between TPE and MPE within this diagnostic gray zone.

Background/Aims: Chronic obstructive pulmonary disease (COPD) management guidelines have increasingly emphasised the importance of exacerbation prevention, and the role of blood eosinophil count (BEC) as a biomarker for inhaled corticosteroids (ICS) response. This study aimed to describe the distribution and stability of BEC and understand real-world treatment patterns among COPD patients in South Korea. Methods: This was a retrospective database analysis using data obtained from the KOrea COPD Subgroup Study (KOCOSS) registry between January 2012 and August 2018. KOCOSS is an ongoing, longitudinal, prospective, multi-centre, non-interventional study investigating early COPD amongst South Korean patients. BEC stability was assessed by calculating the intra-class correlation (ICC) coefficient. “Exacerbators” were patients who had a record of ≥ 1 exacerbation in the 12 months prior to the visit. Results: The study included 2,661 patients with a mean age of 68.6 years. Most patients were male (92.0%). Mean BEC was significantly higher in exacerbators compared to non-exacerbators. Patients with ≥ 2 exacerbations at baseline had a less stable BEC over time (ICC = 0.44) compared to non-exacerbators (ICC = 0.57). Patients with BEC ≥ 300 cells/μL at baseline predominantly received triple therapy (43.8%). Conclusions This study may further develop current understanding on BEC profiles amongst COPD patients in South Korea. BEC measurements are stable and reproducible among COPD patients, which supports its use as a potential biomarker.

Background/Aims: Chronic obstructive pulmonary disease (COPD) management guidelines have increasingly emphasised the importance of exacerbation prevention, and the role of blood eosinophil count (BEC) as a biomarker for inhaled corticosteroids (ICS) response. This study aimed to describe the distribution and stability of BEC and understand real-world treatment patterns among COPD patients in South Korea. Methods: This was a retrospective database analysis using data obtained from the KOrea COPD Subgroup Study (KOCOSS) registry between January 2012 and August 2018. KOCOSS is an ongoing, longitudinal, prospective, multi-centre, non-interventional study investigating early COPD amongst South Korean patients. BEC stability was assessed by calculating the intra-class correlation (ICC) coefficient. “Exacerbators” were patients who had a record of ≥ 1 exacerbation in the 12 months prior to the visit. Results: The study included 2,661 patients with a mean age of 68.6 years. Most patients were male (92.0%). Mean BEC was significantly higher in exacerbators compared to non-exacerbators. Patients with ≥ 2 exacerbations at baseline had a less stable BEC over time (ICC = 0.44) compared to non-exacerbators (ICC = 0.57). Patients with BEC ≥ 300 cells/μL at baseline predominantly received triple therapy (43.8%). Conclusions This study may further develop current understanding on BEC profiles amongst COPD patients in South Korea. BEC measurements are stable and reproducible among COPD patients, which supports its use as a potential biomarker.

Background: Exercise capacity is associated with lung function decline in chronicobstructive pulmonary disease (COPD) patients, but a discrepancy between exercisecapacity and airflow limitation exists. This study aimed to explore factors contributingto this discrepancy in COPD patients. Methods: Data for this prospective study were obtained from the Korean COPD SubgroupStudy. The exercise capacity and airflow limitation were assessed using the6-minute walk distance (6-MWD; m) and forced expiratory volume in 1 second (FEV1).Participants were divided into four groups: FEV1 >50%+6-MWD >350, FEV1 >50%+6-MWD ≤350, FEV1 ≤50%+6-MWD >350, and FEV1 ≤50%+6-MWD ≤350 and their clinicalcharacteristics were compared. Results: A total of 883 patients (male:female, 822:61; mean age, 68.3±7.97 years) wereenrolled. Among 591 patients with FEV1 >50%, 242 were in the 6-MWD ≤350 group, andamong 292 patients with FEV1 ≤50%, 185 were in the 6-MWD >350 group. The multipleregression analyses revealed that male sex (odds ratio [OR], 8.779; 95% confidence interval[CI], 1.539 to 50.087; p=0.014), current smoking status (OR, 0.355; 95% CI, 0.178to 0.709; p=0.003), and hemoglobin levels (OR, 1.332; 95% CI, 1.077 to 1.648; p=0.008)were significantly associated with discrepancies in exercise capacity and airflow limitationin patients with FEV1 >50%. Meanwhile, in patients with FEV1 ≤50%, diffusioncapacity of carbon monoxide (OR, 0.945; 95% CI, 0.912 to 0.979; p=0.002) was significantlyassociated with discrepancies between exercise capacity and airflow limitation. Conclusion The exercise capacity of COPD patients may be influenced by factors otherthan airflow limitation, so these aspects should be considered when assessing andtreating patients.