Purpose: Methacholine bronchial provocation tests (MBPTs) are commonly used to assess airway hyperresponsiveness, but some patients show no significant response. This study aimed to compare the clinical characteristics of asthmatic patients based on their sensitivity to MBPTs. Methods: We conducted a retrospective cross-sectional study involving adult asthmatic patients from 6 university hospitals in South Korea. Patients were categorized into 2 groups: those with MBPT sensitivity (the provocative concentration of methacholine that leads to a 20% reduction in forced expiratory volume in 1 second [PC20]≤ 16 mg/mL) and those with lower sensitivity (PC 20 > 16 mg/mL). Clinical characteristics were compared between the 2 groups. Results: Among 346 patients, 213 had PC 20 ≤ 16 mg/mL and 133 had PC 20 > 16 mg/mL. The PC20> 16 mg/mL group had a higher prevalence of late-onset asthma (P= 0.024) and obesity (P= 0.045). While no significant differences in immunoglobulin E (≥ 200 IU/mL) were found, the PC 20 ≤ 16 mg/mL group had greater T2-high inflammation, such as elevated eosinophil counts and fractional exhaled nitric oxide (P< 0.001 and P= 0.004, respectively). Asthma exacerbations requiring emergency visits or hospitalizations were more frequent in the PC 20 > 16 mg/mL group, despite a lower proportion of patients on higher-step treatments according to Global Initiative for Asthma guidelines. Conclusion Asthmatic patients with PC 20 > 16 mg/mL tend to present with late-onset asthma, less T2-high inflammation, and higher rates of asthma exacerbations. Further studies are needed to clarify the clinical features of asthma patients with PC 20 > 16 mg/mL and assess the long-term significance of these findings.

Purpose: Methacholine bronchial provocation tests (MBPTs) are commonly used to assess airway hyperresponsiveness, but some patients show no significant response. This study aimed to compare the clinical characteristics of asthmatic patients based on their sensitivity to MBPTs. Methods: We conducted a retrospective cross-sectional study involving adult asthmatic patients from 6 university hospitals in South Korea. Patients were categorized into 2 groups: those with MBPT sensitivity (the provocative concentration of methacholine that leads to a 20% reduction in forced expiratory volume in 1 second [PC20]≤ 16 mg/mL) and those with lower sensitivity (PC 20 > 16 mg/mL). Clinical characteristics were compared between the 2 groups. Results: Among 346 patients, 213 had PC 20 ≤ 16 mg/mL and 133 had PC 20 > 16 mg/mL. The PC20> 16 mg/mL group had a higher prevalence of late-onset asthma (P= 0.024) and obesity (P= 0.045). While no significant differences in immunoglobulin E (≥ 200 IU/mL) were found, the PC 20 ≤ 16 mg/mL group had greater T2-high inflammation, such as elevated eosinophil counts and fractional exhaled nitric oxide (P< 0.001 and P= 0.004, respectively). Asthma exacerbations requiring emergency visits or hospitalizations were more frequent in the PC 20 > 16 mg/mL group, despite a lower proportion of patients on higher-step treatments according to Global Initiative for Asthma guidelines. Conclusion Asthmatic patients with PC 20 > 16 mg/mL tend to present with late-onset asthma, less T2-high inflammation, and higher rates of asthma exacerbations. Further studies are needed to clarify the clinical features of asthma patients with PC 20 > 16 mg/mL and assess the long-term significance of these findings.

Purpose: Methacholine bronchial provocation tests (MBPTs) are commonly used to assess airway hyperresponsiveness, but some patients show no significant response. This study aimed to compare the clinical characteristics of asthmatic patients based on their sensitivity to MBPTs. Methods: We conducted a retrospective cross-sectional study involving adult asthmatic patients from 6 university hospitals in South Korea. Patients were categorized into 2 groups: those with MBPT sensitivity (the provocative concentration of methacholine that leads to a 20% reduction in forced expiratory volume in 1 second [PC20]≤ 16 mg/mL) and those with lower sensitivity (PC 20 > 16 mg/mL). Clinical characteristics were compared between the 2 groups. Results: Among 346 patients, 213 had PC 20 ≤ 16 mg/mL and 133 had PC 20 > 16 mg/mL. The PC20> 16 mg/mL group had a higher prevalence of late-onset asthma (P= 0.024) and obesity (P= 0.045). While no significant differences in immunoglobulin E (≥ 200 IU/mL) were found, the PC 20 ≤ 16 mg/mL group had greater T2-high inflammation, such as elevated eosinophil counts and fractional exhaled nitric oxide (P< 0.001 and P= 0.004, respectively). Asthma exacerbations requiring emergency visits or hospitalizations were more frequent in the PC 20 > 16 mg/mL group, despite a lower proportion of patients on higher-step treatments according to Global Initiative for Asthma guidelines. Conclusion Asthmatic patients with PC 20 > 16 mg/mL tend to present with late-onset asthma, less T2-high inflammation, and higher rates of asthma exacerbations. Further studies are needed to clarify the clinical features of asthma patients with PC 20 > 16 mg/mL and assess the long-term significance of these findings.

Purpose: Methacholine bronchial provocation tests (MBPTs) are commonly used to assess airway hyperresponsiveness, but some patients show no significant response. This study aimed to compare the clinical characteristics of asthmatic patients based on their sensitivity to MBPTs. Methods: We conducted a retrospective cross-sectional study involving adult asthmatic patients from 6 university hospitals in South Korea. Patients were categorized into 2 groups: those with MBPT sensitivity (the provocative concentration of methacholine that leads to a 20% reduction in forced expiratory volume in 1 second [PC20]≤ 16 mg/mL) and those with lower sensitivity (PC 20 > 16 mg/mL). Clinical characteristics were compared between the 2 groups. Results: Among 346 patients, 213 had PC 20 ≤ 16 mg/mL and 133 had PC 20 > 16 mg/mL. The PC20> 16 mg/mL group had a higher prevalence of late-onset asthma (P= 0.024) and obesity (P= 0.045). While no significant differences in immunoglobulin E (≥ 200 IU/mL) were found, the PC 20 ≤ 16 mg/mL group had greater T2-high inflammation, such as elevated eosinophil counts and fractional exhaled nitric oxide (P< 0.001 and P= 0.004, respectively). Asthma exacerbations requiring emergency visits or hospitalizations were more frequent in the PC 20 > 16 mg/mL group, despite a lower proportion of patients on higher-step treatments according to Global Initiative for Asthma guidelines. Conclusion Asthmatic patients with PC 20 > 16 mg/mL tend to present with late-onset asthma, less T2-high inflammation, and higher rates of asthma exacerbations. Further studies are needed to clarify the clinical features of asthma patients with PC 20 > 16 mg/mL and assess the long-term significance of these findings.

Purpose: Methacholine bronchial provocation tests (MBPTs) are commonly used to assess airway hyperresponsiveness, but some patients show no significant response. This study aimed to compare the clinical characteristics of asthmatic patients based on their sensitivity to MBPTs. Methods: We conducted a retrospective cross-sectional study involving adult asthmatic patients from 6 university hospitals in South Korea. Patients were categorized into 2 groups: those with MBPT sensitivity (the provocative concentration of methacholine that leads to a 20% reduction in forced expiratory volume in 1 second [PC20]≤ 16 mg/mL) and those with lower sensitivity (PC 20 > 16 mg/mL). Clinical characteristics were compared between the 2 groups. Results: Among 346 patients, 213 had PC 20 ≤ 16 mg/mL and 133 had PC 20 > 16 mg/mL. The PC20> 16 mg/mL group had a higher prevalence of late-onset asthma (P= 0.024) and obesity (P= 0.045). While no significant differences in immunoglobulin E (≥ 200 IU/mL) were found, the PC 20 ≤ 16 mg/mL group had greater T2-high inflammation, such as elevated eosinophil counts and fractional exhaled nitric oxide (P< 0.001 and P= 0.004, respectively). Asthma exacerbations requiring emergency visits or hospitalizations were more frequent in the PC 20 > 16 mg/mL group, despite a lower proportion of patients on higher-step treatments according to Global Initiative for Asthma guidelines. Conclusion Asthmatic patients with PC 20 > 16 mg/mL tend to present with late-onset asthma, less T2-high inflammation, and higher rates of asthma exacerbations. Further studies are needed to clarify the clinical features of asthma patients with PC 20 > 16 mg/mL and assess the long-term significance of these findings.

Background: Haemophilus influenzae is the causative pathogen for various infectious diseases, such as respiratory infections, otitis media, sinusitis, and meningitis. This study aimed to investigate the prevalence and molecular characteristics of β-lactam resistance in non-typeable H. influenzae isolates in South Korea. Methods: In total, 115 non-duplicated H. influenzae isolates were included in this study.Bacterial identification and serotyping were performed using matrix assisted laser desorption ionization-time of flight mass spectrometry and polymerase chain reaction (PCR) of bexA, respectively. Antimicrobial susceptibility was tested using the broth microdilution method.The production of β-lactamase was determined using nitrocefin disks. The presence of blaTEM and blaROB was confirmed using PCR. ftsI was analyzed to identify amino acid mutations in penicillin-binding protein (PBP) 3. Results: Resistance rates to ampicillin, amoxicillin–clavulanate, and cefuroxime were 67.8%, 13.9%, and 32.2%, respectively. None of the isolates were resistant to cefotaxime or ceftriaxone. Among 78 ampicillin-resistant isolates, 71 were β-lactamase-producing ampicillinresistant (BLPAR), and 7 were β-lactamase-non-producing ampicillin-resistant. All BLPAR isolates carried blaTEM, and none carried blaROB. Among 16 amoxicillin–clavulanate-resistant isolates, 15 β-lactamase producers harbored blaTEM. Four to 7 PBP3 mutations per isolate were detected in all 16 non-β-lactamase-producing ampicillin-resistant or cephalosporinresistant isolates. Conclusion Beta-lactam resistance in non-typeable H. influenzae isolates is highly prevalent in South Korea, primarily because of blaTEM and various PBP3 mutations. Therefore, continuous monitoring of antimicrobial resistance rates and mechanisms in non-typeable H.influenzae is necessary.

Objective: Primary frozen shoulder causes significant pain and progressively restricts shoulder movements. Diagnosis is made clinically based on patient history and physical examination. Management is mainly non-invasive owing to its self-limiting clinical course. However, clinical practice guidelines for frozen shoulder have not yet been developed in Korea. The developed guidelines aim to provide evidence-based recommendations for the diagnosis and treatment of frozen shoulder. Methods: A guideline development committee reviewed the literature from four databases (PubMed, Embase, Cochrane Library, and KMbase). Using the Population, Intervention, Comparator, and Outcome (PICO) framework, the committee formulated two backgrounds and 16 key questions to address common clinical concerns. Recommendations were made using the Grading of Recommendations, Assessment, Development, and Evaluation framework. Results: Diabetes, thyroid disease, and dyslipidemia significantly increase the risk of developing a frozen shoulder. Although frozen shoulder is often self-limiting, some patients may experience long-term functional disabilities. Ultrasound and magnetic resonance imaging should be used as adjunctive tools alongside clinical diagnosis, and rather than as independent diagnostic methods. Noninvasive approaches, such as medications, physical modalities, exercises, electrical stimulation, and manual therapy, may reduce pain and improve shoulder function. Other noninvasive interventions have limited evidence, and their application should be based on clinical judgment. Intra-articular steroid injections are recommended for treatment, and physiotherapy or hydrodilation with steroid injections can also be beneficial. Conclusion These guidelines provide evidence-based recommendations for diagnosing and treating primary frozen shoulder.

Background and Objectives: Cardiac resynchronization therapy (CRT) is a treatment option for patients with heart failure and left ventricular (LV) dyssynchrony. However, one-third of CRT patients are non-responders. The objective of this study is to evaluate the feasibility of an in silico electromechanical heart model to predict CRT outcomes. Methods: The three-dimensional heart geometries of 11 patients (age, 64.0 ± 10.7 years, 4 men) with CRT were constructed from cardiac computed tomography images. The finite element method was used to simulate the electrical wave propagation and mechanics in the heart. We coupled cardiac electrical excitation and mechanical contraction with vascular hemodynamics using a lumped parameter model. We predicted the LV end-diastolic and end-systolic volumes and LV ejection fraction (LVEF) after CRT implantation using the in silico CRT simulation model. A CRT responder was defined as a patient with an absolute LVEF increase ≥ 5%. We compared the in silico CRT outcomes with the real CRT outcomes. Results: Two patients were in silico CRT responders, and those 2 patients were also real CRT responders. Nine patients were in silico CRT non-responders, 8 who were real CRT non-responders, and 1 who was a real CRT responder. The in silico CRT outcomes agreed with the real CRT outcomes in 10 of 11 patients. The positive and negative predictive values, accuracy, sensitivity, and specificity of the in silico CRT model were 100%, 88.9%, 90.9%, 66.7%, and 100%, respectively. Conclusion The in silico CRT simulation model is feasible for predicting real CRT outcomes.

The Korean Breast Cancer Society (KBCS) has collected nationwide registry data on clinicopathologic characteristics and treatment since 1996. This study aimed to analyze the clinical characteristics of breast cancer in Korea and assess changes in breast cancer statistics for 2021 using data from the KBCS registry and the Korean Central Cancer Registry. In 2021, 34,628 women were newly diagnosed with breast cancer. The median age of women diagnosed with breast cancer was 53.4 years, with the highest incidence occurring in the 40–49 age group. The most common molecular subtype was hormone receptor-positive and human epidermal growth factor receptor 2 (HER2)-negative, accounting for 69.1% of cases, while HER2-positive subtypes comprised 19.3%. During the coronavirus disease 2019 pandemic, the national breast cancer screening rate declined. However, the incidence of early-stage breast cancer (stages 0 and I) continued to increase, accounting for 65.6% of newly diagnosed cases in 2021. Our results showed that the overall survival rate for patients with breast cancer has improved, primarily due to a rise in early-stage diagnoses and advancements in treatment.

The Korean Breast Cancer Society (KBCS) has collected nationwide registry data on clinicopathologic characteristics and treatment since 1996. This study aimed to analyze the clinical characteristics of breast cancer in Korea and assess changes in breast cancer statistics for 2021 using data from the KBCS registry and the Korean Central Cancer Registry. In 2021, 34,628 women were newly diagnosed with breast cancer. The median age of women diagnosed with breast cancer was 53.4 years, with the highest incidence occurring in the 40–49 age group. The most common molecular subtype was hormone receptor-positive and human epidermal growth factor receptor 2 (HER2)-negative, accounting for 69.1% of cases, while HER2-positive subtypes comprised 19.3%. During the coronavirus disease 2019 pandemic, the national breast cancer screening rate declined. However, the incidence of early-stage breast cancer (stages 0 and I) continued to increase, accounting for 65.6% of newly diagnosed cases in 2021. Our results showed that the overall survival rate for patients with breast cancer has improved, primarily due to a rise in early-stage diagnoses and advancements in treatment.