The Diagnostic Role of Repeated Biopsy of Thyroid Nodules with Atypia of Undetermined Significance with Architectural Atypia on Core-Needle Biopsy

Background@#We aimed to evaluate the utility of repeat biopsy of thyroid nodules classified as atypia of undetermined significance with architectural atypia (IIIB) on core-needle biopsy (CNB). @*Methods@#This retrospective study evaluated patients with thyroid nodules categorized as IIIB on CNB between 2013 and 2015. Demographic characteristics, subsequent biopsy results, and ultrasound (US) images were evaluated. The malignancy rates of nodules according to number of CNBs and the number of IIIB diagnoses was compared. Demographic and US features were evaluated to determine factors predictive of malignancy. @*Results@#Of 1,003 IIIB nodules on CNB, the final diagnosis was determined for 328 (32.7%) nodules, with 121 of them confirmed as malignant, resulting in a malignancy rate of 36.9% (95% confidence interval, 31.7% to 42.1%). Repeat CNB was performed in 248 nodules (24.7%), with 75 (30.2%), 131 (52.8%), 13 (5.2%), 26 (10.5%), one (0.4%), and two (0.8%) reclassified into categories II, IIIB, IIIA, IV, V, and VI, respectively. Malignancy rates were not significantly affected by the number of CNBs (P=0.291) or the number of IIIB diagnoses (P=0.473). None of the nodules confirmed as category II on repeat CNB was malignant. US features significantly associated with malignancy (P<0.003) included solid composition, irregular margins, microcalcifications, and high suspicion on the US risk stratification system. @*Conclusion@#Repeat biopsy of nodules diagnosed with IIIB on CNB did not increase the detection of malignancy but can potentially reduce unnecessary surgery. Repeat biopsy should be performed selectively, with US features guiding the choice between repeat biopsy and diagnostic surgery.

Drawing Guideline for JKMS Manuscripts (06): Scatter Plot

The appropriate plot effectively conveys the author’s conclusions to the readers. Journal of Korean Medical Science is providing a series of guidelines to show you how to make consistent and excellent plots more easily. In this article, we introduce scatter plots and more.

Evaluation of the Appropriateness of Platelet Transfusions at Two Tertiary Hospitals / 대한수혈학회지

Background@#Appropriate platelet transfusion is essential for patient blood management and allocating limited healthcare resources. Therefore, this study evaluated the appropriateness of platelet transfusion in two tertiary hospitals. @*Methods@#At Chonnam National University Hospital (Hospital A) and Chonnam National University Hwasun Hospital (Hospital B), 1,470 platelet transfusions (299 and 1,171 cases at Hospitals A and B, respectively) during a single month were reviewed retrospectively using the Korean Transfusion Guidelines (5th edition). @*Results@#The most common indications were therapeutic transfusion to ensure hemostasis (54.8%) at Hospital A and to prevent spontaneous bleeding in patients with hematologic/oncologic diseases (65.8%) at Hospital B. Overall, 87.3% and 76.3% of transfusions were appropriate at Hospitals A and B, respectively. According to the different transfusion indications, the therapeutic transfusions were appropriate in more than 80% of cases in both hospitals.The appropriateness of prophylactic transfusions against spontaneous bleeding was 80.7% and 69.3%, respectively, and those before surgery or invasive procedures were 72.0% and 66.2%, respectively. Of the 38 and 278 inappropriate transfusions in Hospitals A and B, respectively (as determined by pre-transfusion platelet counts), most cases had platelet counts between 50 and 100×109 /L in Hospital A (23 cases) and between 20 and 50×109 /L in Hospital B (198 cases). @*Conclusion@#The two hospitals differed in terms of transfusion indications, appropriateness, and cases of inappropriateness. The indications and appropriateness of platelet transfusion should be reviewed in real practice on a hospital-by-hospital basis to improve transfusion management.

Pompholyx and Eczematous Reaction After Intravenous Immunoglobulin Therapy for Patient with Guillain-Barré Syndrome / 대한피부과학회지

Cutaneous adverse events associated with intravenous immunoglobulin (IVIG) have a relatively low significance, ranging from 0.4% to 6%. In Korean dermatology literature, eczematous reactions associated with the use of IVIG have been underestimated. A 34-year-old male presented with a 2-week history of multiple vesicles on both hands and diffuse eczematous lesions on the trunk and both arms. He had been diagnosed with Guillain-Barré syndrome and had received IVIG at a dosage of 0.4 g/kg/d for 5 days during hospitalization. One week after discharge, cutaneous manifestations developed, starting with tiny blisters on both hands and progressing to eczematous patches on the trunk and arms.Histopathologic examination revealed spongiotic dermatitis with intracorneal bullae formation. A diagnosis of palmar pompholyx and systemic eczematous reaction associated with the administration of IVIG was made. Treatment with systemic corticosteroid, antihistamines and topical steroid was initiated. At a 2-week follow-up, significant improvement was observed.

Association Between Flexible Work Arrangement and Sleep Problems Among Paid Workers: Using 6th Korean Working Conditions Survey

Background@#As social distancing persists and interest in work-life balance grows, more companies are adopting flexible work policies. While there have been studies on sleep disorders associated with different types of work, such as shift work, research exploring the relationship between flexible work schedules and sleep disorders is still limited, particularly among Korean workers. @*Methods@#We performed a secondary analysis of the 6th Korean Working Conditions Survey, focusing on 31,243 paid workers out of a total of 50,538 participants. We defined flexible workers as those who set their own working hours. Sleep disorders were divided into three categories: ‘difficulty falling asleep,’ ‘frequent waking during sleep,’ and ‘waking up feeling exhausted and fatigued.’ Using scores derived from three specific symptoms, the Minimal Insomnia Symptoms Scale (MISS) was calculated to assess the prevalence of insomnia. We used chi-square tests to analyze demographic and job-related differences. A multivariate logistic regression analysis was employed to identify any relationship between flexible work schedules and sleep disorders. @*Results@#Significant differences were found between flexible and non-flexible workers regarding age, income level, education level, and job type. Flexible workers reported sleep-related symptoms significantly more often. The odds ratio for insomnia was 1.40 (95% CI 1.21–1.61). For males, the odds ratio was 1.68 (1.36–2.08). @*Conclusion@#This study establishes a correlation between flexible work schedules and sleep disorders among Korean salaried workers. Potential causes could include changes in circadian rhythm, increased work demands, and extended working hours. To precisely determine causality and associated diseases, further research is required.

Roles of Inflammatory Biomarkers in Exhaled Breath Condensates in Respiratory Clinical Fields / 결핵및호흡기질환

Background@#Exhaled condensates contain inflammatory biomarkers; however, their roles in the clinical field have been under-investigated. @*Methods@#We prospectively enrolled subjects admitted to pulmonology clinics. We collected exhaled breath condensates (EBC) and analysed the levels of six and 12 biomarkers using conventional and multiplex enzyme-linked immunosorbent assay, respectively. @*Results@#Among the 123 subjects, healthy controls constituted the largest group (81 participants; 65.9%), followed by the preserved ratio impaired spirometry group (21 patients; 17.1%) and the chronic obstructive pulmonary disease (COPD) group (21 patients; 17.1%). In COPD patients, platelet derived growth factor-AA exhibited strong positive correlations with COPD assessment test (ρ=0.5926, p=0.0423) and COPD-specific version of St. George’s Respiratory Questionnaire (SGRQ-C) score (total, ρ=0.6725, p=0.0166; activity, ρ=0.7176, p=0.0086; and impacts, ρ=0.6151, p=0.0333). Granzyme B showed strong positive correlations with SGRQ-C score (symptoms, ρ=0.6078, p=0.0360; and impacts, ρ=0.6007, p=0.0389). Interleukin 6 exhibited a strong positive correlation with SGRQ-C score (activity, ρ=0.4671, p=0.0378). The absolute serum eosinophil and basophil counts showed positive correlations with pro-collagen I alpha 1 (ρ=0.6735, p=0.0164 and ρ=0.6295, p=0.0283, respectively). In healthy subjects, forced expiratory volume in 1 second (FEV1)/forced vital capacity demonstrated significant correlation with CC chemokine ligand 3 (CCL3)/macrophage inflammatory protein 1 alpha (ρ=0.3897 and p=0.0068). FEV1 exhibited significant correlation with CCL11/eotaxin (ρ=0.4445 and p=0.0017). @*Conclusion@#Inflammatory biomarkers in EBC might be useful to predict quality of life concerning respiratory symptoms and serologic markers. Further studies are needed.

Insulin-Derived Cutaneous Amyloidosis: A Possible Complication of Repeated Insulin Injections

Primary localized cutaneous amyloidosis (PLCA) is characterized by extracellular deposition of pathological fibril aggregation of proteins in the skin without systemic involvement.Macular amyloidosis, lichen (papular) amyloidosis, and nodular amyloidosis are three different subtypes of PLCA. Although the pathological mechanism of PLCA has not yet been clarified, it is assumed that a nucleus formation of amyloid fibril is formed due to repeated external stimulation, such as subcutaneous injection, which often poses diagnostic challenges. Herein, we present a 54-year-old Korean male patient with cutaneous localized amyloidosis which occurred after repeated local insulin injections, and discuss the relationship between insulin therapy in patients with diabetes mellitus and dermal amyloid deposition.

Fixed Drug Eruption in a Patient Taking Valacyclovir without Cross-Reactivity to Acyclovir

Fixed drug eruption (FDE) is a well-defined hyperpigmented patch that recurs in a fixed location each time a particular drug is taken. Common causative agents of FDE are nonsteroidal anti-inflammatory drugs, non-narcotic analgesics, sedatives, anticonvulsants, sulfonamides, and tetracycline. We report a 33-year-old male who presented with a recurrent, localized, brownish-to-erythematous macule and papules on the peri-philtrum area two hours after taking valacyclovir. Three episodes of valacyclovir ingestion for treatment of Herpes simplex virus infection provoked a similar skin rash at the same site. Histopathology results showed vacuolar degeneration in the basal layer of the epidermis, pigmentary incontinence, and perivascular inflammatory cell infiltration in the papillary dermis. Although patch test and skin prick test showed negative responses to acyclovir and valacyclovir, an intradermal test showed a positive reaction only to valacyclovir. The oral provocation test to acyclovir and valacyclovir showed a positive reaction only to valacyclovir. Through drug history, histopathological examination, patch test, intradermal test, and oral provocation test, we established a final diagnosis of FDE due to valacyclovir without cross-reactivity to acyclovir. To find alternative therapeutic drugs, we suggest diagnostic tests with not only the suspected drugs, but also other drugs in the same class.

Drawing Guideline for JKMS Manuscripts (05): Plots for Numeric Data

The appropriate plot effectively conveys the author’s conclusions to the readers. Journal of Korean Medical Science will provide a series of special articles to show you how to more easily make consistent and excellent plots. In this article, we will cover plots with numeric data.

The Profile of Early Sedation Depth and Clinical Outcomes of Mechanically Ventilated Patients in Korea

Background@#Current international guidelines recommend against deep sedation as it is associated with worse outcomes in the intensive care unit (ICU). However, in Korea the prevalence of deep sedation and its impact on patients in the ICU are not well known. @*Methods@#From April 2020 to July 2021, a multicenter, prospective, longitudinal, noninterventional cohort study was performed in 20 Korean ICUs. Sedation depth extent was divided into light and deep using a mean Richmond Agitation–Sedation Scale value within the first 48 hours. Propensity score matching was used to balance covariables; the outcomes were compared between the two groups. @*Results@#Overall, 631 patients (418 [66.2%] and 213 [33.8%] in the deep and light sedation groups, respectively) were included. Mortality rates were 14.1% and 8.4% in the deep and light sedation groups (P = 0.039), respectively. Kaplan-Meier estimates showed that time to extubation (P < 0.001), ICU length of stay (P = 0.005), and death P = 0.041) differed between the groups. After adjusting for confounders, early deep sedation was only associated with delayed time to extubation (hazard ratio [HR], 0.66; 95% confidence inter val [CI], 0.55– 0.80; P < 0.001). In the matched cohort, deep sedation remained significantly associated with delayed time to extubation (HR, 0.68; 95% 0.56–0.83; P < 0.001) but was not associated with ICU length of stay (HR, 0.94; 95% CI, 0.79–1.13; P = 0.500) and in-hospital mortality (HR, 1.19; 95% CI, 0.65–2.17; P = 0.582). @*Conclusion@#In many Korean ICUs, early deep sedation was highly prevalent in mechanically ventilated patients and was associated with delayed extubation, but not prolonged ICU stay or in-hospital death.

Treatment Outcomes of Oral Acitretin versus Alitretinoin for Psoriasis:A Retrospective Review of 65 Cases / 대한피부과학회지

Background@#Oral acitretin (ACT) has been approved for the treatment of psoriasis (PSO), whereas alitretinoin (ALI) has been prescribed off-label. Few studies have compared the efficacy of these two therapeutics. @*Objective@#To evaluate the clinical outcomes of oral ACT versus ALI for treating PSO. @*Methods@#Sixty-five patients diagnosed with PSO and treated with ACT or ALI were reviewed. Patient demographics, clinical efficacy, and adverse effects were evaluated. Treatment efficacy was assessed using physician’s global assessment (PGA) and psoriasis area and severity index (PASI). @*Results@#A total of 38 cases in the ACT group and 27 cases in the ALI group in PSO were retrospectively reviewed. No significant intergroup differences were noted in the proportion of patients achieving PGA score of “clear” or “almost clear” (18.42% vs. 22.22%; p=0.71). The reduction rate of PASI from baseline was higher in the ALI group (24.30% vs. 22.74%; p=0.68), while the rate of achieving 75% improvement in PASI was higher in the ACT group (18.42% vs. 14.81%; p=0.75); no significantly differences were noted. The ALI group had fewer adverse effects (6/27 [22.22%]) than the ACT group (10/38 [26.32%]), and no severe events occurred in either group. @*Conclusion@#ALI can be considered an off-label treatment option for a limited patient population.

Macakurzin C Derivatives as a Novel Pharmacophore for Pan-Peroxisome Proliferator-Activated Receptor Modulator

The natural flavonoid macakurzin C (1) exhibited adiponectin biosynthesis-inducing activity during adipogenesis in human bone marrow mesenchymal stem cells and its molecular mechanism was directly associated with a pan-peroxisome proliferator-activated receptor (PPAR) modulator affecting all three PPAR subtypes α, γ, and δ. In this study, increases in adiponectin biosynthesisinducing activity by macakurzin C derivatives (2–7) were studied. The most potent adiponectin biosynthesis-inducing compound 6, macakurzin C 3,5-dimethylether, was elucidated as a dual PPARα/γ modulator. Compound 6 may exhibit the most potent activity because of the antagonistic relationship between PPARδ and PPARγ. Docking studies revealed that the O-methylation of macakurzin C to generate compound 6 significantly disrupted PPARδ binding. Compound 6 has therapeutic potential in hypoadiponectinemia-related metabolic diseases.

Niclosamide Inhibits Aortic Valve Interstitial Cell Calcification by Interfering with the GSK-3β/β-Catenin Signaling Pathway

The most common heart valve disorder is calcific aortic valve stenosis (CAVS), which is characterized by a narrowing of the aortic valve. Treatment with the drug molecule, in addition to surgical and transcatheter valve replacement, is the primary focus of researchers in this field. The purpose of this study is to determine whether niclosamide can reduce calcification in aortic valve interstitial cells (VICs). To induce calcification, cells were treated with a pro-calcifying medium (PCM). Different concentrations of niclosamide were added to the PCM-treated cells, and the level of calcification, mRNA, and protein expression of calcification markers was measured. Niclosamide inhibited aortic valve calcification as observed from reduced alizarin red s staining in niclosamide treated VICs and also decreased the mRNA and protein expressions of calcification-specific markers: runt-related transcription factor 2 and osteopontin. Niclosamide also reduced the formation of reactive oxygen species, NADPH oxidase activity and the expression of Nox2 and p22 phox . Furthermore, in calcified VICs, niclosamide inhibited the expression of β-catenin and phosphorylated glycogen synthase kinase (GSK-3β), as well as the phosphorylation of AKT and ERK. Taken together, our findings suggest that niclosamide may alleviate PCM-induced calcification, at least in part, by targeting oxidative stress mediated GSK-3β/β-catenin signaling pathway via inhibiting activation of AKT and ERK, and may be a potential treatment for CAVS.

Improving Accuracy and Reliability of Hearing Tests: An Exploration of International Standards

This study explores the internal standards for hearing tests and benefits of implementing international standard protocols, including the International Organization for Standardization (ISO) and International Electrotechnical Commission (IEC), and discusses how ISO and IEC standards provide a framework for designing, calibrating, assessing hearing test instruments and methods, and exchanging and comparing data globally. ISO and IEC standards for hearing tests improve accuracy, reliability, and consistency of test results by applying standardized methods and environments. Moreover, they promote international harmonization and data interoperability, enabling information exchange and research collaboration. Those standards for hearing tests are beneficial but have challenges and limitations, such as variation in equipment and calibration, lag in updating standards, variation in implementation and compliance, and lack of coverage of clinical aspects, cultural diversity, and linguistic diversity. These affect the quality and interpretation of test results. Adapting ISO or IEC standards locally would improve their applicability and acceptability, while balancing customization and compatibility with global standards.

Development of a Machine Learning Model for Diagnosing Schizophrenia and Bipolar Disorder Based on Diffusion Tensor Imaging: A Preliminary Study / 생물치료정신의학

Objectives@#This study aimed to develop a machine learning model for diagnosing schizophrenia (SZ) and bipolar disorder (BD) based on diffusion tensor imaging (DTI) data. @*Methods@#We used 3T-magnetic resonance imaging to examine SZ, BD, healthy control (HC) subjects (aged 20-50 years, n=65 in each group). Applying Support Vector Machine (SVM) to fractional anisotropy (FA) values, we built classification models of SZ and HC, BD and HC, and SZ and BD. Features of white matter (WM) tracts were selected through recursive feature elimination, and 5-fold cross validation was performed. @*Results@#The SVM models classified SZ and BD from HC with a mean accuracy of 83.5% and 75.4%, respectively. The SZ-BD classification model archived 75.0% accuracy. These classification models used FA values in 15-18 WM tracts as features, including the retrolenticular part of the internal capsule, superior corona radiata, cingulum, and superior fronto-occipital fasciculus. @*Conclusions@#This study presented a preliminary machine learning model to diagnose SZ and BD based on DTI data. Our findings also suggest that there might be a specific pattern of abnormalities in WM integrity that can differentiate the two psychotic disorders.

Bullous Pilomatricoma Arising at a BNT162b2 mRNA COVID-19 Vaccination Site / 대한피부과학회지

Pilomatricoma is a common benign tumor that originates from hair matrix cells. Bullous pilomatricoma (BP) is a rare variant that often occurs on the upper extremities. A 23-year-old male presented with a cyst on the left upper arm for 6 months. He received the BNT162b2 (Pfizer) mRNA COVID-19 vaccine in the same location approximately 6 months prior to presentation. The lesion appeared 1 week after inoculation and gradually enlarged.Physical examination revealed a 2.5-×2.0-cm-sized, pinkish cystic nodule on the left upper arm. The lesion was excised, and histopathological examination showed a well-circumscribed nodule composed of basophilic cells and eosinophilic shadow cells. Finally, the patient was diagnosed with BP. The exact cause of BP formation following vaccination is yet to be determined; however, this report presents the possibility of BP occurrence in individuals with chronic skin lesions at the site of vaccination.

Epithelioid Blue Nevus with No Evidence of Carney Complex / 대한피부과학회지

Epithelioid blue nevus (EBN) is a rare variant of blue nevus characterized by large polygonal pigmented melanocytes. As EBN was first described in patients with Carney complex, familial lentiginosis, and low-grade multi-organ neoplasia syndrome, sporadic cases without such clinical features have been reported and debated as having considerable histopathological overlap with animal-type melanoma. A 34-year-old male presented with a well-defined, 2.0-×1.8-cm-sized, dome-shaped, grayish mass on the anterior aspect of the left ankle. A complete surgical resection of the lesion was performed. Histopathological findings revealed a well-circumscribed round tumor in the reticular dermis. Heavily pigmented epithelioid melanocytes were admixed with the collagen bundles. The lesion was diagnosed as EBN. A follow-up period of 9 months showed no evidence of recurrence or metastasis.Here, we report a sporadic case of EBN, which is rare in the Korean population.

Validation of CT-Based Risk Stratification System for Lymph Node Metastasis in Patients With Thyroid Cancer

Objective@#To evaluate the computed tomography (CT) features for diagnosing metastatic cervical lymph nodes (LNs) in patients with differentiated thyroid cancer (DTC) and validate the CT-based risk stratification system suggested by the Korean Thyroid Imaging Reporting and Data System (K-TIRADS) guidelines. @*Materials and Methods@#A total of 463 LNs from 399 patients with DTC who underwent preoperative CT staging and ultrasound-guided fine-needle aspiration were included. The following CT features for each LN were evaluated: absence of hilum, cystic changes, calcification, strong enhancement, and heterogeneous enhancement. Multivariable logistic regression analysis was performed to identify independent CT features associated with metastatic LNs, and their diagnostic performances were evaluated. LNs were classified into probably benign, indeterminate, and suspicious categories according to the K-TIRADS and the modified LN classification proposed in our study. The diagnostic performance of both classification systems was compared using the exact McNemar and Kosinski tests. @*Results@#The absence of hilum (odds ratio [OR], 4.859; 95% confidence interval [CI], 1.593–14.823; P = 0.005), strong enhancement (OR, 28.755; 95% CI, 12.719–65.007; P < 0.001), and cystic changes (OR, 46.157; 95% CI, 5.07–420.234; P = 0.001) were independently associated with metastatic LNs. All LNs showing calcification were diagnosed as metastases. Heterogeneous enhancement did not show a significant independent association with metastatic LNs. Strong enhancement, calcification, and cystic changes showed moderate to high specificity (70.1%–100%) and positive predictive value (PPV) (91.8%–100%). The absence of the hilum showed high sensitivity (97.8%) but low specificity (34.0%). The modified LN classification, which excluded heterogeneous enhancement from the K-TIRADS, demonstrated higher specificity (70.1% vs. 62.9%, P = 0.016) and PPV (92.5% vs. 90.9%, P = 0.011) than the K-TIRADS. @*Conclusion@#Excluding heterogeneous enhancement as a suspicious feature resulted in a higher specificity and PPV for diagnosing metastatic LNs than the K-TIRADS. Our research results may provide a basis for revising the LN classification in future guidelines.

Clinical efficacy of angiotensin receptor-neprilysin inhibitor in de novo heart failure with reduced ejection fraction

Background/Aims@#We aimed to analyze the efficacy of angiotensin receptor-neprilysin inhibitor (ARNI) by the disease course of heart failure (HF). @*Methods@#We evaluated 227 patients with HF in a multi-center retrospective cohort that included those with left ventricular ejection fraction (LVEF) ≤ 40% undergoing ARNI treatment. The patients were divided into patients with newly diagnosed HF with ARNI treatment initiated within 6 months of diagnosis (de novo HF group) and those who were diagnosed or admitted for HF exacerbation for more than 6 months prior to initiation of ARNI treatment (prior HF group). The primary outcome was a composite of cardiovascular death and worsening HF, including hospitalization or an emergency visit for HF aggravation within 12 months. @*Results@#No significant differences in baseline characteristics were reported between the de novo and prior HF groups. The prior HF group was significantly associated with a higher primary outcome (23.9 vs. 9.4%) than the de novo HF group (adjusted hazard ratio 2.52, 95% confidence interval 1.06–5.96, p = 0.036), although on a higher initial dose. The de novo HF group showed better LVEF improvement after 1 year (12.0% vs 7.4%, p = 0.010). Further, the discontinuation rate of diuretics after 1 year was numerically higher in the de novo group than the prior HF group (34.4 vs 18.5%, p = 0.064). @*Conclusions@#The de novo HF group had a lower risk of the primary composite outcome than the prior HF group in patients with reduced ejection fraction who were treated with ARNI.

Low Skeletal Muscle Mass and Clinical Outcomes in Chronic Obstructive Pulmonary Disease / 결핵및호흡기질환

Background@#In patients with chronic obstructive pulmonary disease (COPD), decreased muscle mass is a frequently encountered comorbidity in clinical practice. However, the evaluation of muscle mass in patients with COPD in real-world practice is rare. @*Methods@#We retrospectively reviewed the electronic medical records of all patients with COPD who underwent bioelectrical impedance analysis at least once between January 2011 and December 2021 in three hospitals. Then, we analyzed the performance rate of muscle mass measurement in the patients and the correlation between muscle mass, clinical parameters, and COPD prognosis. @*Results@#Among the 24,502 patients with COPD, only 270 (1.1%) underwent muscle mass measurements. The total skeletal muscle mass index was significantly correlated with albumin, alanine transaminase, and creatinine to cystatin C ratio in patients with COPD (r=0.1614, p=0.011; r=0.2112, p=0.001; and r=0.3671, p=0.001, respectively). Acute exacerbation of COPD (AE COPD) was significantly correlated with muscle mass, especially the truncal skeletal muscle mass index (TSMI) in males (r=–0.196, p=0.007). In the multivariate analysis, TSMI and cystatin C were significant risk factors for AE COPD (hazard ratio, 0.200 [95% confidence interval, CI, 0.048 to 0.838] and 4.990 [95% CI, 1.070 to 23.278], respectively). @*Conclusion@#Low muscle mass negatively affects the clinical outcomes in patients with COPD. Despite its clinical significance, muscle mass measurement is performed in a small proportion of patients with COPD. Therefore, protocols and guidelines for the screening of sarcopenia in patients with COPD should be established.