Young Yull Koh

Acute Exacerbation of Idiopathic Pulmonary Fibrosis: Incidence, Risk Factors, and Outcome

Although acute exacerbation of idiopathic pulmonary fibrosis (IPF) has become well recognised, the reported incidence and outcomes are highly variable, and risk factors are unknown. The aim of this study was to estimate the incidence, risk factors and impact of acute exacerbations, and other known causes of rapid deterioration. This was a retrospective review of 461 patients with IPF (269 cases were biopsy-proven). The median follow-up period was 22.9 months. Rapid deterioration requiring hospitalisation occurred in 163 (35.4%) patients, with multiple episodes in 42 patients. Acute exacerbation was the most frequent cause (55.2%), followed by infection. The 1- and 3-yr incidences of acute exacerbation were 14.2 and 20.7%, respectively. Never having smoked and low forced vital capacity (FVC) were significant risk factors. The in-hospital mortality rate was 50.0%, and the 1- and 5-yr survival rates from the initial diagnosis were 56.2 and 18.4%, respectively. Acute exacerbation was a significant predictor of poor survival after the initial diagnosis, along with increased age, low FVC and diffusing capacity of the lung for carbon monoxide, and steroid use with or without cytotoxic therapy. 1- and 3-yr incidences of acute exacerbation were 14.2 and 20.7%, respectively. Never having smoked and low FVC were risk factors. Acute exacerbation had a serious impact on the overall survival of the patients with IPF.

Comparison of two commercial interferon-γ assays for diagnosing Mycobacterium tuberculosis infection

The clinical usefulness of ex vivo interferon-γ assays may largely depend on the assay format and epidemiological status of tuberculosis (TB) in the region studied. From July 2004 to June 2005 a prospective comparison study was undertaken at a tertiary referral hospital in South Korea. The results of tuberculin skin tests (TST) and the commercially available QuantiFERON-TB Gold (QFT-G) and T SPOT-TB (SPOT) assays were compared in an intermediate TB-burden country. Of the 224 participants studied, results from all three tests (TST, QFT-G, and SPOT) were available in 218; 87 with active TB and 131 at a low risk for TB. Using 10 mm as a cut-off for TST, SPOT sensitivity (96.6%) was significantly higher than that seen for TST (66.7%) and QFT-G (70.1%). QFT-G showed superior specificity over TST (91.6 versus 78.6%). Although the specificity of QFT-G was higher than that of SPOT (91.6 versus 84.7%), the difference was not statistically significant. Whilst some differences were found in the performance of the two commercialised interferon-γ assays, they seemed to be superior in their detection of Mycobacterium tuberculosis infection compared with tuberculin skin tests. The most appropriate choice of interferon-γ assay to use may depend on the clinical setting.

Lung cancer in patients with idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) was reported to be associated with increased risk of lung cancer as a result of the occurrence of atypical or dysplastic epithelial changes in fibrosis which progressed to invasive malignancy. In that situation, the cancer will develop in the area of major fibrosis. To investigate the direct relationship between fibrosis and cancer development, the real concordance rate of the two lesions in the chest computed tomography (CT) was analysed and compared to the histological types of lung cancer. The subjects included 63 patients with combined lung cancer and IPF (IPF-CA), 218 patients with lone IPF, and 2,660 patients with primary lung cancer. All patients were diagnosed at Asan Medical Center during the same period. The age, percentage of smokers, and the male sex were significantly higher in IPF-CA compared with lone IPF. The odds ratio of smoking was 2.71 compared to nonsmoking IPF controls. In IPF-CA, 56% of the cancer was located in the periphery of the lung and 52% in the upper lobe. The majority of the cancers (64%) were found in the nonfibrotic area at chest CT. The most frequent cell type was squamous cell carcinoma (35%), and there was no significant difference in the cancer cell type between IPF-CA and total lung cancer population. These findings suggest that in combined lung cancer and idiopathic pulmonary fibrosis patients, the features of the lung cancer are similar to the total lung cancer population.

Effect of roxithromycin on airway responsiveness in children with bronchiectasis: a double-blind, placebo-controlled study

Increased airway responsiveness (AR) is frequently associated with bronchiectasis. Roxithromycin is a new semisynthetic macrolide antibiotic that also has anti-inflammatory activities. This study was designed to see whether roxithromycin could favourably alter the degree of AR in patients with bronchiectasis and increased AR. Twenty five children with bronchiectasis, who had an increased AR (defined as a provocative concentration of methacholine causing a 20% fall in forced expiratory volume in one second (FEV1) (PC20) <25 mg x mL(-1) evaluated by the dosimeter method), were randomized, double-blind into two parallel groups. Thirteen of the children were treated with roxithromycin (4 mg x kg(-1) b.i.d.) for 12 weeks and 12 received placebo. FEV1, sputum purulence and leucocyte scores were assessed every 3 weeks. To estimate AR, high-dose methacholine challenge tests were performed before and after treatment. On the dose-response curve to methacholine, PD20 and maximal response (two indices of AR) were measured. Changes in FEV1 were not observed during the course of the study in both groups. A significant improvement in sputum features was noted after 6 weeks of treatment in the roxithromycin group. After 12 weeks of roxithromycin therapy, the geometric mean (range of 1 SD) of provocative cumulative dose producing a 20% fall in FEV1 (PD20) increased significantly (p<0.01) to 169.2 (83.2-344.2) breath units (BU) (1 BU denotes one inhalation of 1 mg x mL(-1) methacholine) and the mean+/-SD of maximal response decreased significantly (p<0.01) to 32.5+/-6.8%, as compared with the initial values (PD20 87.1 (47.3-160.4) BU; maximal response 40.9+/-7.4%). No significant changes in either parameter were observed in the placebo group. Our results indicate that roxithromycin may decrease the degree of airway responsiveness in patients with bronchiectasis and increased airway responsiveness. Further study is necessary to determine the mechanism by which roxithromycin reduces airway responsiveness in bronchiectasis and its clinical impact.

Acute Effects of Asian Dust Events on Respiratory Symptoms and Peak Expiratory Flow in Children with Mild Asthma

The aim of this study was to investigate the possible adverse effects of Asian dust events on respiratory health in asthmatic children. Fifty-two children with mild asthma were studied for eight consecutive weeks in the spring of 2004 (March 8 to May 2). During the study period, five Asian dust days were identified; we included a lag period of two days following each of the events. Subjects recorded their respiratory symptom diaries and peak expiratory flow (PEF) twice daily during the study period; and they underwent methacholine bronchial challenge tests. The subjects reported a significantly higher frequency of respiratory symptoms during the Asian dust days than during the control days. They showed significantly more reduced morning and evening PEF values, and more increased PEF variability (10.1%±3.5% vs. 5.5%±2.2%) during the Asian dust days than during the control days. Methacholine PC20 was not significantly different between before and after the study period (geometric mean: 2.82 mg/mL vs. 3.16 mg/mL). These results suggest that the short-term Asian dust events might be associated with increased acute respiratory symptoms and changes in PEF outcomes. However, there might be little long-term influence on airway hyperresponsiveness in children with mild asthma.

Cough variant asthma is associated with a higher wheezing threshold than classic asthma

Cough variant asthma is an occult form of asthma in which the only sign or symptom is chronic cough. It is a common problem amongst all ages that frequently goes unrecognized, leading to under diagnosis and under treatment. To characterize the pathophysiological abnormalities in these patients, we performed bronchial provocation tests with methacholine using the stepwise doubling concentration technique, and measured the concentration of methacholine and the severity of airway obstruction when wheezing was first detected. Airway hyper responsiveness, defined as PC20 in the cough variant asthma group was not significantly different from that of classic asthma. There was a good correlation between the PCW (the concentration of methacholine causing wheezing) and the PC20 with the PCW values higher than PC20 values in both groups. However, in the cough variant asthma group, the PCW: PC20 ratio was greater than that of the classic asthma group. Furthermore, the mean % fall in FEV1 at which wheezing was first detected in the former group was significantly larger than that of the latter group. The results indicated that the mechanism for the manifestation of cough without wheeze in the cough variant asthma may be a higher wheezing threshold, i.e. wheezing becomes audible at the greater degree of airway obstruction than classic asthma. They suggested that patients with cough variant asthma may represent a subset of asthmatic subjects whose airways are less able to produce a wheeze.

Clinical and Epidemiological Comparison of Human Metapneumovirus and Respiratory Syncytial Virus in Seoul, Korea, 2003-2008

Human metapneumovirus (HMPV) shares clinical and epidemiological characteristics with well-known respiratory syncytial virus (RSV). The aim of this study was to investigate the clinical and epidemiological differences between HMPV- and RSV-induced wheezing illnesses. A total of 1,008 nasopharyngeal aspirate specimens was collected from 1,008 pediatric patients hospitalized with acute respiratory tract infection at Inje University Sanggye Paik Hospital from December 2003 to April 2008, and tested for seven common respiratory viruses. Conditions classified as wheezing illness were bronchiolitis, reactive airways disease, and bronchial asthma. HMPV caused a significantly lower proportion of wheezing illness when compared to RSV (48.1% vs. 82.2%, P<0.05). HMPV-induced wheezing illness occurred predominantly in older patients when compared to RSV patients (P<0.001). RSV infections peaked in the fall and winter followed by peaks of HMPV infection in winter and spring. Eosinophil counts were significantly higher (P<0.01) in RSV patients when compared to HMPV patients. These results show that human metapneumovirus patients exhibit several different clinical and epidemiological characteristics, such as higher proportion of wheezing illness, age and seasonal incidence, and eosinophil counts, when compared to RSV patients.

Bronchial hyperresponsiveness in young children with allergic rhinitis and its risk factors

Background:  Subjects with allergic rhinitis but no clinical evidence of asthma have greater bronchial hyperresponsiveness (BHR), and several factors have been implicated as its determinants. However, studies in young children are lacking. The aims of this study were to evaluate the prevalence of BHR in young children with allergic rhinitis and to investigate its risk factors.

Regulation of mucociliary motility by nitric oxide and expression of nitric oxide synthase in the human sinus epithelial cells

Objectives This study was performed to investigate the changes in ciliary beat frequency (CBF) after treatment with L‐arginine in the human sinus mucosa and to determine the distribution of inducible nitric oxide synthase (iNOS) and endothelial nitric oxide synthase (eNOS) in the healthy sinus mucosa.

A randomized intervention of montelukast for post-bronchiolitis: effect on eosinophil degranulation.

OBJECTIVE To investigate the effect of montelukast on eosinophil degranulation and recurrent wheezing episodes in post-respiratory syncytial virus (RSV) bronchiolitis. STUDY DESIGN Two hundred infants (age, 6-24 months) who were hospitalized with their first episode of acute RSV bronchiolitis were randomized in a double-blind, placebo-controlled, parallel comparison of 4-mg montelukast granules (RSV-MONT group) or matching placebo (RSV-PLC group) administered for 3 months. Serum eosinophil-derived neurotoxin (EDN) levels were measured (primary outcome), and recurrent wheezing was documented (secondary outcome) for 12 months. Comparisons were made with control subjects (control group, n = 50). RESULTS At the end of the 3-month treatment period, the RSV-PLC group (n = 71) exhibited significantly elevated EDN levels (P < .0001), and the RSV-MONT group (n = 79) showed significantly decreased EDN levels (P < .01) when compared with the initial levels. As a result, EDN levels in the 2 RSV groups significantly differed at this point (P < .0001) and remained different for the entire 12-month follow-up period. Cumulative recurrent wheezing episodes at 12 months were significantly lower in the RSV-MONT group (P = .039). CONCLUSION Montelukast treatment reduces eosinophil degranulation and is associated with a decrease in recurrent wheezing episodes in post-RSV bronchiolitis.