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Asthma is a chronic inflammatory airway disease that is characterized by variable airflow obstruction. The Korean Asthma Study Group of the Korean Academy of Tuberculosis and Respiratory Diseases has recently updated the Korean Asthma Guideline. This review summarizes the updated Korean Asthma Guideline. Asthma prevalence is increasing worldwide, and in Korea. Variable airflow obstruction can be confirmed by bronchodilator response or other tests, and should be established prior to the controller medication. A low-dose inhaled corticosteroid-formoterol is used to alleviate symptoms in all treatment step, and it can be used as a controller as well as reliever in steps 3–5. This approach is preferred, because it reduces the risk of severe exacerbations, compared to the use of short-acting β2-agonist as reliever. In severe asthma, phenotype/endotype based on the underlying inflammation should be evaluated. For type 2 severe asthma, the biologics should be considered.
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Background@#The Global Initiative for Chronic Obstructive Lung Disease (GOLD) update 2023 proposed new definitions of chronic obstructive pulmonary disease (COPD) and COPD exacerbation. However, an agreement on the definitions has not been made, either internationally or domestically. This study aimed to reach an agreement between experts on the new definitions of COPD and COPD exacerbation in South Korea. @*Methods@#A modified Delphi method was used to make an agreement on the definitions of COPD and COPD exacerbation proposed by the GOLD update 2023. We performed two rounds of the survey including 15 Korean experts on COPD, asthma, and tuberculosis. @*Results@#More than two-thirds of the experts agreed on 12 of the 13 statements related to the definitions of COPD and COPD exacerbation in the two rounds of the survey. The experts agreed on the definitions of COPD and COPD exacerbation that should be revised in line with the definitions proposed by the GOLD update 2023. However, the experts showed an uncertain opinion on the statement that the definition of COPD includes patients with persistent airflow obstruction due to bronchiectasis. @*Conclusion@#Based on this Delphi survey, experts’ agreement was made on the definitions of COPD and COPD exacerbation proposed by the GOLD update 2023.
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Background@#The prevalence of chronic obstructive pulmonary disease (COPD) increases with age, and aging is an important risk factor for COPD development. In the era of global aging, demographic information about the prevalence of and factors associated with COPD are important to establish COPD care plans. However, limited information is available in rapidly aging societies, including Korea. @*Methods@#We conducted a cross-sectional observational study using Korea National Health and Nutrition Examination Survey data from 2015–2019. We included 15,613 participants and analyzed trends of and factors associated with COPD. @*Results@#During the study period, the overall prevalence of COPD was 12.9%. Over five years, the yearly prevalence of COPD was fairly constant, ranging from 11.5% to 13.6%. Among individuals aged ≥ 70 years, nearly one-third met COPD diagnostic criteria. In the multivariable analysis, age 70 years or older was the most strong factor associated with COPD (adjusted odds ratio [aOR], 17.86; 95% confidence interval [CI], 14.16–22.52; compared with age 40–49), followed by asthma (aOR, 3.39; 95% CI, 2.44–4.71), male sex (aOR, 2.64; 95% CI, 2.18–3.19), and current smokers (aOR, 2.60; 95% CI, 2.08–3.25). Additionally, exsmokers, low income, decreased forced expiratory volume in 1 second %pred, and a history of pulmonary tuberculosis were associated with COPD. On the other hand, body mass index (BMI) ≥ 25 kg/m 2 (aOR, 0.62; 95% CI, 0.54–0.71; compared with BMI 18.5–24.9 kg/m 2 ) had an inverse association with COPD. @*Conclusion@#Recent trends in the prevalence of COPD in South Korea are relatively stable.Approximately one-third of participants aged 70 years and older had COPD. Aging was the most important factor associated with COPD.
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Background@#Respiratory pathogen infections and air pollution are main causes of acute exacerbation of chronic obstructive pulmonary disease (AECOPD). Air pollution has a direct effect on the airway epithelial barrier and the immune system, which can have an influence on infection. However, studies on the relationship between respiratory infections and air pollutants in severe AECOPD are limited. Thus, the objective of this study was to investigate the correlation between air pollution and respiratory pathogen in severe AECOPD. @*Methods@#This multicenter observational study was conducted by reviewing electronic medical records of patients with AECOPD at 28 hospitals in South Korea. Patients were divided into four groups according to the comprehensive air-quality index (CAI) used in Korea. Identification rates of bacteria and viruses of each group were analyzed. @*Results@#Viral pathogens were identified in 270 (36.7%) of 735 patients. Viral identification rate was different (P = 0.012) according to air pollution. Specifically, the virus detection rate was 55.9% in the group of CAI ‘D’ with the highest air pollution. It was 24.4% in the group of CAI ‘A’ with the lowest air pollution. This pattern was clearly seen for influenza virus A (P = 0.042). When further analysis was performed with particulate matter (PM), the higher/lower the PM level, the higher/lower the virus detection rate. However, no significant difference was found in the analysis related to bacteria. @*Conclusion@#Air pollution may make COPD patients more susceptible to respiratory viral infections, especially influenza virus A. Thus, on days with poor air quality, COPD patients need to be more careful about respiratory infections.
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Background@#The value of tiotropium bromide (TIO) in neutrophilic asthma was meaningful in previous study. We hypothesized that TIO’s mechanism of action is associated with histone deacetylase 2 (HDAC2) activity, which is key for controlling the transcription of inflammatory cytokines and usually downregulated in neutrophilic asthma. @*Methods@#The effects of TIO and dexamethasone (DEX) on HDAC2 activity, nuclear factor kappa B (NF-κB), and C-X-C motif chemokine ligand 1 (CXCL1) were evaluated in neutrophilic asthma mouse model (C57BL, 6-week-old). An in-vitro study was conducted using primary human bronchial/tracheal epithelial (HBE) cells from asthma patients.Western blot analyses were performed for phospho-phospholipase Cγ-1 (PLCγ-1) and inositol trisphosphate (IP3 ) receptors (IP3 R) with treating lipopolysaccharide (LPS) and TIO. @*Results@#Ovalbumin was used to induce eosinophilic inflammation in this study. After neutrophilic asthma was induced by LPS (O+L group), HDAC2 activity was diminished with increased NF-κB activity and CXCL1 compared to the control group. TIO significantly improved NF-κB activity, CXCL1, and HDAC2 activity compared with the O+L group in in-vivo study (P < 0.05, each). Western blot analyses showed that LPS treated HBE cells from asthma patients increased PLCγ-1 and diminished IP3 receptor levels. After TIO treatment, recovery of IP3 R and improved PLCγ-1 levels were observed. @*Conclusion@#These results support the hypothesis that TIO modulates inflammation by recovering HDAC2 activity from the acetylcholine-stimulated inflammation cascade in neutrophilic asthma. The detailed inflammation cascade of recovering HDAC2 activity by TIO might be associated with PLCγ-1-IP3-IP3R mediated intracellular calcium ion pathway.
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It is unclear whether young adults with chronic obstructive pulmonary disease (COPD) are at an increased risk of rapid lung function decline. A total of 2,934 Korean adults aged 40–49 years who had consecutive lung function measurements were included. COPD was defined as pre-bronchodilator forced expiratory volume in 1 second (FEV 1 )/forced vital capacity < lower limit of normal. The risk of rapid decline in FEV 1 , defined as ≥ 60 mL/year, was assessed using multivariable logistic regression analysis. In the multivariable model, a significantly higher risk of rapid decline in FEV 1 was observed for the COPD group compared with the non-COPD group (adjusted odds ratio, 1.89; 95% confidence interval, 1.18–2.95), which was especially significant in subjects with FEV 1 less than the median value (< 110%pred) (P interaction = 0.017) and inactive physical activity (P interaction = 0.039). In conclusion, the risk of rapid FEV 1 decline was higher in young adults with COPD than in those without COPD, especially in those with FEV 1 less than the median value and inactive physical activity.
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Asthma is the most common chronic respiratory disease, affecting 1% to 18% of the population worldwide. It is characterized by various respiratory symptoms, such as wheezing, shortness of breath, chest tightness and cough, and variable airflow limitation. People with asthma often have periods of worsened symptoms and airway obstruction called exacerbations, which can be fatal. We would like to provide the updated clinical management protocols for patients with asthma.Current Concepts: The goal of asthma treatment is to control symptoms adequately and minimize exacerbations. Anti-inflammatory and bronchodilator therapies are the mainstay of asthma treatment and are recommended as a stepwise approach. The pharmacological treatment of asthma involves evaluating and reviewing the current control status based on the symptoms, future risk of exacerbation, comorbidities, side effects, and patient’s satisfaction. Asthma symptoms in some patients remain uncontrolled despite intensive treatment. The development of biomarkers, evaluation of the patient’s phenotype, and personalized treatment, including biologics, can provide new and effective treatment opportunities.Discussion and Conclusion: Successful asthma management can be achieved through accurate diagnosis of asthma, evaluation of the control stages, correct use of controllers and relievers, adjustment of asthma triggers, personalized approach, and training in self-management.
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Chronic obstructive pulmonary disease (COPD) is characterized by airflow limitation due to chronic airway inflammation and destruction of the alveolar structure from persistent exposure to oxidative stress. The body has various antioxidant mechanisms for efficiently coping with such oxidative stress. The nuclear factor erythroid 2-related factor 2 (Nrf2)–antioxidant response element (ARE) is a representative system. Dysregulation of the Nrf2-ARE pathway is responsible for the development and promotion of COPD. Furthermore, COPD severity is also closely related to this pathway. There has been a clinical impetus to use Nrf2 for diagnostic and therapeutic purposes. Therefore, in this work, we systematically reviewed the clinical significance of Nrf2 in COPD patients, and discuss the value of Nrf2 as a potential COPD biomarker.
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Background@#We evaluated the effect of particulate matter (PM) and cigarette smoke extract (CSE) on bronchial epithelial cell survival, as well as oxidative stress and autophagy levels. Moreover, we aimed to assess the effect of the antioxidant N-acetylcysteine (NAC) on the adverse effects of PM and CSE exposure. @*Methods@#Normal human bronchial epithelial cells (BEAS-2B cells) were exposed to urban PM with or without CSE, after which cytotoxic effects, including oxidative stress and autophagy levels, were measured. After identifying the toxic effects of urban PM and CSE exposure, the effects of NAC treatment on cell damage were evaluated. @*Results@#Urban PM significantly decreased cell viability in a concentration-dependent manner, which was further aggravated by simultaneous treatment with CSE. Notably, pretreatment with NAC at 10 mM for 1 hour reversed the cytotoxic effects of PM and CSE co-exposure. Treatment with 1, 5, and 10 mM NAC was shown to decrease reactive oxygen species levels induced by exposure to both PM and CSE. Additionally, the autophagy response assessed via LC3B expression was increased by PM and CSE exposure, and this also attenuated by NAC treatment. @*Conclusion@#The toxic effects of PM and CSE co-exposure on human bronchial epithelial cells, including decreased cell viability and increased oxidative stress and autophagy levels, could be partly prevented by NAC treatment.
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Background@#Asthma and chronic obstructive pulmonary disease (COPD) are airway diseases with similar clinical manifestations, despite differences in pathophysiology. AsthmaCOPD overlap (ACO) is a condition characterized by overlapping clinical features of both diseases. There have been few reports regarding the prevalence of ACO in COPD and severe asthma cohorts. ACO is heterogeneous; patients can be classified on the basis of phenotype differences. This study was performed to analyze the prevalence of ACO in COPD and severe asthma cohorts. In addition, this study compared baseline characteristics among ACO patients according to phenotype. @*Methods@#Patients with COPD were prospectively enrolled into the Korean COPD subgroup study (KOCOSS) cohort. Patients with severe asthma were prospectively enrolled into the Korean Severe Asthma Registry (KoSAR). ACO was defined in accordance with the updated Spanish criteria. In the COPD cohort, ACO was defined as bronchodilator response (BDR) ≥ 15% and ≥ 400 mL from baseline or blood eosinophil count (BEC) ≥ 300 cells/μL. In the severe asthma cohort, ACO was defined as age ≥ 35 years, smoking ≥ 10 pack-years, and postbronchodilator forced expiratory volume in 1 s/forced vital capacity < 0.7. Patients with ACO were divided into four groups according to smoking history (threshold: 20 pack-years) and BEC (threshold: 300 cells/μL). @*Results@#The prevalence of ACO significantly differed between the COPD and severe asthma cohorts (19.8% [365/1,839] vs. 12.5% [104/832], respectively; P < 0.001). The percentage of patients in each group was as follows: group A (light smoker with high BEC) – 9.1%; group B (light smoker with low BEC) – 3.7%; group C (moderate to heavy smoker with high BEC) – 73.8%; and group D (moderate to heavy smoker with low BEC) – 13.4%. Moderate to heavy smoker with high BEC group was oldest, and showed weak BDR response. Age, sex, BDR, comorbidities, and medications significantly differed among the four groups. @*Conclusion@#The prevalence of ACO differed between COPD and severe asthma cohorts. ACO patients can be classified into four phenotype groups, such that each phenotype exhibits distinct characteristics.
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Background@#Although respiratory tract infection is one of the most important factors triggering acute exacerbation of chronic obstructive pulmonary disease (AE-COPD), limited data are available to suggest an epidemiologic pattern of microbiology in South Korea. @*Methods@#A multicenter observational study was conducted between January 2015 and December 2018 across 28 hospitals in South Korea. Adult patients with moderate-to-severe acute exacerbations of COPD were eligible to participate in the present study. The participants underwent all conventional tests to identify etiology of microbial pathogenesis. The primary outcome was the percentage of different microbiological pathogens causing AE-COPD. A comparative microbiological analysis of the patients with overlapping asthma–COPD (ACO) and pure COPD was performed. @*Results@#We included 1,186 patients with AE-COPD. Patients with pure COPD constituted 87.9% and those with ACO accounted for 12.1%. Nearly half of the patients used an inhaled corticosteroid-containing regimen and one-fifth used systemic corticosteroids. Respiratory pathogens were found in 55.3% of all such patients. Bacteria and viruses were detected in 33% and 33.2%, respectively. Bacterial and viral coinfections were found in 10.9%. The most frequently detected bacteria were Pseudomonas aeruginosa (9.8%), and the most frequently detected virus was influenza A (10.4%). Multiple bacterial infections were more likely to appear in ACO than in pure COPD (8.3% vs. 3.6%, p=0.016). @*Conclusion@#Distinct microbiological patterns were identified in patients with moderate-to-severe AE-COPD in South Korea. These findings may improve evidence-based management of patients with AE-COPD and represent the basis for further studies investigating infectious pathogens in patients with COPD.
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Background@#We evaluated the long-term effects of domiciliary noninvasive positive-pressure ventilation (NIPPV) used to treat patients with chronic obstructive pulmonary disease (COPD). @*Methods@#Databases were searched to identify randomized controlled trials of COPD with NIPPV for longer than 1 year. Mortality rates were the primary outcome in this meta-analysis. The eight trials included in this study comprised data from 913 patients. @*Results@#The mortality rates for the NIPPV and control groups were 29% (118/414) and 36% (151/419), suggesting a statistically significant difference (risk ratio [RR], 0.79; 95% confidence interval [CI], 0.65–0.95). Mortality rates were reduced with NIPPV in four trials that included stable COPD patients. There was no difference in admission, acute exacerbation and quality of life between the NIPPV and control groups. There was no significant difference in withdrawal rates between the two groups (RR, 0.99; 95% CI, 0.72–1.36; p=0.94). @*Conclusion@#Maintaining long-term nocturnal NIPPV for more than 1 year, especially in patients with stable COPD, decreased the mortality rate, without increasing the withdrawal rate compared with long-term oxygen treatment.
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Background@#Because the etiologies of bronchiectasis and related diseases vary significantly among different regions and ethnicities, this study aimed to develop a diagnostic bundle for bronchiectasis in South Korea. @*Methods@#A modified Delphi method was used to develop expert consensus statements on a diagnostic bundle for bronchiectasis in South Korea. Initial statements proposed by a core panel, based on international bronchiectasis guidelines, were discussed in an online meeting and two email surveys by a panel of experts (≥70% agreement). @*Results@#The study involved 21 expert participants, and 30 statements regarding a diagnostic bundle for bronchiectasis were classified as recommended, conditional, or not recommended. The consensus statements of the expert panel were as follows: A standardized diagnostic bundle is useful in clinical practice; diagnostic tests for specific diseases, including immunodeficiency and allergic bronchopulmonary aspergillosis, are necessary when clinically suspected; initial diagnostic tests, including sputum microbiology and spirometry, are essential in all patients with bronchiectasis, and patients suspected with rare causes such as primary ciliary dyskinesia should be referred to specialized centers. @*Conclusion@#Based on this Delphi survey, expert consensus statements were generated including specific diagnostic, laboratory, microbiological, and pulmonary function tests required to manage patients with bronchiectasis in South Korea.
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Background@#The effect of underlying chronic obstructive pulmonary disease (COPD) on coronavirus disease 2019 (COVID-19) during a pandemic is controversial. The purpose of this study was to examine the prognosis of COVID-19 according to the underlying COPD. @*Methods@#COVID-19 patients were assessed using nationwide health insurance data. Comorbidities were evaluated using the modified Charlson Comorbidity Index (mCCI) which excluded COPD from conventional CCI scores. Baseline characteristics were assessed. Univariable and multiple logistic and linear regression analyses were performed to determine effects of variables on clinical outcomes. Ages, sex, mCCI, socioeconomic status, and underlying COPD were selected as variables. @*Results@#COPD patients showed older age (71.3±11.6 years vs. 47.7±19.1 years, p<0.001), higher mCCI (2.6±1.9 vs. 0.8±1.3, p<0.001), and higher mortality (22.9% vs. 3.2%, p<0.001) than non-COPD patients. The intensive care unit admission rate and hospital length of stay were not significantly different between the two groups. All variables were associated with mortality in univariate analysis. However, underlying COPD was not associated with mortality unlike other variables in the adjusted analysis. Older age (odds ratio [OR], 1.12; 95% confidence interval [CI], 1.11–1.14; p<0.001), male sex (OR, 2.29; 95% CI, 1.67–3.12; p<0.001), higher mCCI (OR, 1.30; 95% CI, 1.20–1.41; p<0.001), and medical aid insurance (OR, 1.55; 95% CI, 1.03–2.32; p=0.035) were associated with mortality. @*Conclusion@#Underlying COPD is not associated with a poor prognosis of COVID-19.
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Background/Aims@#Hypoxemia in chronic obstructive pulmonary disease (COPD) leads to reduced ability to exercise, decreased quality of life, and, eventually, increased mortality. Home oxygen therapy in patients with severe COPD reduces distress symptoms and mortality rates. However, there have been few studies on physicians’ prescription behavior toward home oxygen therapy. Therefore, we investigated the respiratory specialists’ perspective on home oxygen therapy. @*Methods@#In this cross-sectional, study, a questionnaire was completed by 30 pulmonary specialists who worked in tertiary hospitals and prescribed home oxygen therapy. The questionnaire consisted of 28 items, including 15 items on oxygen prescription for outpatients, four for inpatients, and nine on service improvement. @*Results@#All physicians were prescribing less than 2 L/min of oxygen for either 24 (n = 10, 33.3%) or 15 hours (n = 9, 30.3%). All (n = 30) used pulse oximetry, 26 (86.7%) analyzed arterial blood gas. Thirteen physicians had imposed restrictions and recommended oxygen use only during exercise or sleep. Sixteen (53.3%) physicians were educating their patients about home oxygen therapy. Furthermore, physicians prescribed home oxygen to patients that did not fit the typical criteria for longterm oxygen therapy, with 30 prescribing it for acute relief and 17 for patients with borderline hypoxemia. @*Conclusions@#This study identified the prescription pattern of home oxygen therapy in Korea. Respiratory physicians prescribe home oxygen therapy to hypoxemic COPD patients for at least 15 hours/day, and at a rate of less than 2 L/min. More research is needed to provide evidence for establishing policies on oxygen therapy in COPD patients.
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Background@#This study aimed to perform meta-analyses to update a previous systematic review (SR) conducted by the US Preventive Services Task Force (USPSTF) to evaluate the benefits and harms of screening for chronic obstructive pulmonary disease (COPD) in asymptomatic adults. @*Methods@#MEDLINE, EMBASE, Cochrane Library, and regional databases were searched from their inception to January 2020. Studies for diagnostic accuracy, preventive services effect, treatment efficacy, and treatment harms were included. @*Results@#Eighteen studies were included, and twelve of these were newly added in this update. In meta-analyses, the pooled sensitivity and specificity for COPD diagnosis using spirometry were 73.4% and 89.0%, respectively. The relative effect of smoking cessation intervention with screening spirometry, presented as abstinence rate, was not statistically significant (risk ratio [RR], 1.21; 95% confidence interval [CI], 0.87–1.67) when all selected studies were pooled, but screening on smoking cessation was effective (RR, 1.58; 95% CI, 1.14–2.19) when limited to studies with smoking cessation programs that provided smoking cessation medicines or intensive counseling at public health centers or medical institutions. @*Conclusion@#In this study, no direct evidence for the impact on health outcomes of screening asymptomatic adults for COPD was identified similar to the previous SR. Further research is necessary to confirm the benefits of COPD screening.
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Background@#The Korea National Health and Nutrition Examination Survey (KNHANES) is a well-designed survey to collect national data, which many researchers have used for their studies. In KNHANES, although portable spirometry was used, its reliability has not been verified. @*Methods@#We prospectively enrolled 58 participants from four Korean institutions. The participants were classified into normal pattern, obstructive pattern, and restrictive pattern groups according to their previous spirometry results. Lung function was estimated by conventional spirometry and portable spirometry, and the results were compared. @*Results@#The intraclass correlation coefficients of forced vital capacity (FVC) (coefficient, 9.993; 95% confidence interval [CI], 0.988–0.996), forced expiratory volume in 1 second (FEV1) (coefficient, 0.997; 95% CI, 0.995–0.998), FEV1/FVC ratio (coefficient, 0.995; 95% CI, 0.992–0.997), and forced expiratory flow at 25–75% (FEF25–75%; coefficient, 0.991; 95% CI, 0.984–0.994) were excellent (all p<0.001). In the subgroup analysis, the results of the three parameters were similar in all groups. In the overall and subgroup analyses, Pearson’s correlation of all the parameters was also excellent in the total (coefficient, 0.986–0.994; p<0.001) and subgroup analyses (coefficient, 0.915–0.995; p<0.001). In the paired t-test, FVC, FEV1/FVC, and FEF25–75% estimated by the two instruments were statistically different. However, FEV1 was not significantly different. @*Conclusion@#Lung function estimated by portable spirometry was well-correlated with that estimated by conventional spirometry. Although the values had minimal differences between them, we suggest that the spirometry results from the KNHANES are reliable.
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Cough is the most common respiratory symptom that can have various causes. It is a major clinical problem that can reduce a patient’s quality of life. Thus, clinical guidelines for the treatment of cough were established in 2014 by the cough guideline committee under the Korean Academy of Tuberculosis and Respiratory Diseases. From October 2018 to July 2020, cough guidelines were revised by members of the committee based on the first guidelines. The purpose of these guidelines is to help clinicians efficiently diagnose and treat patients with cough. This article highlights the recommendations and summary of the revised Korean cough guidelines. It includes a revised algorithm for the evaluation of acute, subacute, and chronic cough. For a chronic cough, upper airway cough syndrome (UACS), cough variant asthma (CVA), and gastroesophageal reflux disease (GERD) should be considered in differential diagnoses. If UACS is suspected, first-generation antihistamines and nasal decongestants can be used empirically. In cases with CVA, inhaled corticosteroids are recommended to improve cough. In patients with suspected chronic cough due to symptomatic GERD, proton pump inhibitors are recommended. Chronic bronchitis, bronchiectasis, bronchiolitis, lung cancer, aspiration, intake of angiotensin-converting enzyme inhibitor, intake of dipeptidyl peptidase-4 inhibitor, habitual cough, psychogenic cough, interstitial lung disease, environmental and occupational factors, tuberculosis, obstructive sleep apnea, peritoneal dialysis, and unexplained cough can also be considered as causes of a chronic cough. Chronic cough due to laryngeal dysfunction syndrome has been newly added to the guidelines.
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Background/Aims@#Postbronchodilator forced expiratory volume in 1 second (FEV1)/forced vital capacity (FVC) less than 0.7 using spirometry is the golden standard to diagnose airf low limitation of chronic obstructive pulmonary disease (COPD). Recently, measuring FEV6 has been suggested as an alternative to measure FVC. Studies about the cut-off value for FEV1/FEV6 to diagnose airflow limitation have shown variable results, with values between 0.7 and 0.8. The purpose of this study was to determine the best cut-off value of FEV1/FEV6 to detect airflow limitation using handheld spirometry. @*Methods@#We recruited subjects over 40 years of age with smoking history over 10 pack-years. Participants underwent measurements with both handheld spirometry and conventional spirometry. We calculated the sensitivity and specificity of the value of FEV1/FEV6 using receiver-operating characteristic (ROC) curve analysis to obtain the diagnostic accuracy of handheld spirometry to detect airflow limitation. @*Results@#A total of 290 subjects were enrolled. Their mean age and smoking amount were 63.1 years and 31.6 pack-years, respectively. According to our ROC curve analysis, when FEV1/FEV6 ratio was 73%, sensitivity and specificity were the maximum and the area under the ROC curve was 0.93, showing an excellent diagnostic accuracy. Sensitivity, specificity, positive predictive value, and negative predictive value were 86.7%, 89.7%, 88.0%, and 88.5%, respectively. Participants with FEV1/FEV6 ≤ 73% had lower FEV1 predicted value compared to those with FEV1/FEV6 > 73% (65.4% vs. 86.5%, p < 0.001). @*Conclusions@#In summary, we demonstrate that the value of 73% in FEV1/FEV6 using handheld spirometry has the best sensitivity and specificity to detect airflow limitation in subjects with risk of COPD.
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Background/Aims@#Air trapping is associated with unfavorable outcomes in chronic obstructive pulmonary disease (COPD). The present study evaluated the association between longitudinal changes in air trapping with pulmonary function, computed tomography (CT) parameters and exacerbation. @*Methods@#Patients enrolled in the Korean Obstructive Lung Disease (KOLD) study cohort from June 2005 to October 2015 were included. The study patients were categorized into four groups according to the change in residual volume to total lung capacity ratio (RV/TLC) over 3 years. The RV/TLC was considered abnormal when it was ≥ 40% and normal when it was < 40%. @*Results@#A total of 279 patients were categorized into four groups: 76 in the “normal to normal” (N→N) group, 34 in the “abnormal to normal” (A→N) group, 33 in the “normal to abnormal” (N→A) group, and 136 in the “abnormal to abnormal” (A→A) group. For forced expiratory volume in 1 second and forced vital capacity (FVC), respectively, group A→N showed a large increase of 266 mL (p < 0.001) and 381 mL (p < 0.001), group N→A showed a marked decrease of 216 mL (p < 0.001) and 332 mL(p = 0.029), and group A→A showed a decrease of 16 mL (p = 0.426) and 6 mL (p = 0.011) compared to group N→N. Group A→N showed a significant decrease of –0.013 in expiratory to inspiratory ratio of the mean lung density (p < 0.001), while group A→N showed an increase of 0.005 (p < 0.001). @*Conclusions@#Patients with COPD whose RV/TLC changed from normal to abnormal showed deterioration of pulmonary function and worsening of CT parameters simultaneously