Multiple myeloma is an incurable malignant plasma cell-originating cancer. Although its treatment outcomes have improved with the use of glucocorticoids, alkylating drugs, and novel agents, including proteasome inhibitors (bortezomib and carfilzomib) and immunomodulatory drugs (thalidomide, lenalidomide, and pomalidomide), relapse remains a serious problem. Strategies to improve outcomes following autologous stem cell transplantation and frontline treatments in non-transplant patients include consolidation to intensify therapy and improve the depth of response and maintenance therapy to achieve long-term disease control. Many clinical trials have reported increased progression-free and overall survival rates after consolidation and maintenance therapy. The role of consolidation/maintenance therapy has been assessed in patients eligible and ineligible for transplantation and is a valuable option in clinical trial settings. However, the decision to use consolidation and/or maintenance therapy needs to be guided by the individual patient situation in actual clinical practice. This review analyzes the currently available evidence from several reported clinical trials to determine the optimal consolidation and maintenance therapy in clinical practice.

Epidemiologically, multiple myeloma (MM) is a malignant disorder of plasma cells with a higher incidence among Western populations than among Asians. However, there is growing evidence of a recent increase in the age-standardized incidence rate (ASR) of MM in Asian countries, particularly Korea. Application of novel agents has resulted in significant improvement of treatment outcomes, and the advances are ongoing with the recent introduction and U.S. Food and Drug Administration's approval of newer agents, including carfilzomib, ixazomib, elotuzumab, and daratumumab. In concert with the technical advances in the cytogenetic and molecular diagnostics of MM, modifications of its diagnosis and staging system have been attempted for better risk stratification. The modified diagnostic criteria from the International Myeloma Working Group in 2014 enabled a strategy of more active treatment for some patients with smoldering MM, with an ultra-high risk of progression, and fine-tuned the definition of end-organ damage, known as CRAB (hypercalcemia, renal insufficiency, anemia, and bone lesions). Considering Korea's trend of aging at an unprecedented rate, we can expect that the ASR of MM will maintain a gradual increase for many years to come; therefore, MM will be a cancer of critical importance from both medical and socioeconomic perspectives in Korea.

Endoscopic findings of the background gastric mucosa are important in the Helicobacter pylori-seroprevalent population. It is strongly correlated not only with the risk of gastric cancer, but also with the excretion ability of gastric mucosa cells. In noninfected subjects, common endoscopic findings are regular arrangement of collecting venules, chronic superficial gastritis, and erosive gastritis. In cases of active H. pylori infection, nodularity on the antrum, hemorrhagic spots on the fundus, and thickened gastric folds are common endoscopic findings. The secreting ability of the gastric mucosa cells is usually intact in both noninfected and actively infected stomachs, and the intragastric condition becomes hyperacidic upon inflammation. Increased serum pepsinogen II concentration correlates well with active H. pylori infection, and also indicates an increased risk of diffuse-type gastric cancer. In chronic inactive H. pylori infection, metaplastic gastritis and atrophic gastritis extending from the antrum (closed-type chronic atrophic gastritis) toward the corpus (open-type chronic atrophic gastritis) are common endoscopic findings. The intragastric environment is hypoacidic and the risk of intestinal-type gastric cancer is increased in such conditions. Furthermore, there is a decrease in serum pepsinogen I concentration when the secreting ability of the gastric mucosa cells is damaged. Serologic and endoscopic changes that occur upon H. pylori infection are important findings for estimating the secreting ability of the gastric mucosa cells, and could be applied for the secondary prevention of gastric cancer.

Diabetes mellitus is an increasing global health problem. Guidelines for diabetic care recommend management of lifestyle and risk factors (glucose, blood pressure, and cholesterol), as well as regular screening for complications associated with treatment of the conditions related to diabetes. The prevalence of diabetes increased from 8.6% to 11.0% from 2001 to 2013. According to the diabetes fact sheet 2015, the proportion of patients with diabetes treated with antihypertensive medications increased from 56.0% to 62.5% from 2006 to 2013, and 49.5% of those with diabetes were being treated with lipid-lowering medications in 2013, a 1.8-fold increase since 2006. According to the 2014 Korea National Health and Nutrition Examination Survey data, 45.6% of patients with diabetes achieved a hemoglobin A1c level of < 7.0%, 72.8% achieved a blood pressure of < 140/85 mmHg, and 58.0% achieved a low density lipoprotein cholesterol level of < 100 mg/dL. Only 19.7% of patients with diabetes had good control of all three of these parameters. Despite improvements in health promotion efforts, the rates of adherence to medication and risk-factor control are low. Therefore, a systematic approach to managing diabetes, including self-management education, is needed to prevent or delay complications. The government needs to establish a long-term policy to address the growing burden of diabetes.

Background/Aims: Inflammatory bowel disease (IBD) may also involve various extra-intestinal organs. Clinical studies have found asymptomatic/symptomatic pulmonary involvement in 1% to 6% of patients with IBD. The present study histopathologically investigated pulmonary involvement in an experimental model of colitis in order to demonstrate pulmonary tissue involvement in IBD and to expose potential etiological factors. It also explored the relation between inflammation and tissue concentrations of vascular endothelial growth factor (VEGF) and tumor necrosis factor ${\alpha}$ ($TNF-{\alpha}$). Methods: The study comprised 24 male Wistar albino rats. The rats were divided into four groups of six rats each. Acute colitis was induced in two separate groups using either the dextran sulphate sodium (DSS) or trinitrobenzene sulfonic acid (TNBS) method, while the other two groups were used as controls for each model of colitis. Wallace scoring was used for macroscopic assessment of colitis, and the lungs were histopathologically examined. Concentrations of VEGF and $TNF-{\alpha}$ in pulmonary tissue were measured by the enzyme-linked immunosorbent assay method. Results: The number of animals that had alveolar hemorrhage was significantly higher in the TNBS-induced colitis and DSS-induced colitis groups compared to their own control groups (p = 0.015 and p = 0.015, respectively). VEGF and $TNF-{\alpha}$ concentrations in pulmonary tissues were significantly increased in both the TNBS colitis and DSS colitis groups compared to their own control groups (p = 0.002 and p = 0.004, respectively; and p = 0.002 and p = 0.002, respectively). Conclusions: The present study demonstrated that significant and serious histopathological changes directly associated with colitis occur in the lungs in IBD.

Background/Aims: To evaluate the therapeutic outcomes of the endoscopic submucosal dissection (ESD) technique for the treatment of gastric subepithelial tumors (SETs). Methods: A systematic literature review was conducted using the core databases. Data on the complete resection rates and the procedure-related perforation rates were extracted and analyzed. A random effects model was then applied for this meta-analysis. Results: In all, 288 patients with 290 SETs were enrolled from nine studies (44 SETs originated from the submucosal layer; 246 SETs originated from the muscularis propria layer). The mean diameter of the lesions ranged from 17.99 to 38 mm. Overall, the pooled complete resection rate was estimated to be 86.2% (95% confidence interval [CI], 78.9 to 91.3). If the analysis was limited to the lesions that originated from the submucosal layer, the pooled complete resection rate was 91.4% (95% CI, 77.9 to 97). If the analysis was limited to the lesions that originated from the muscularis propria, the pooled complete resection rate was 84.4% (95% CI, 78.7 to 88.8). The pooled procedure-related gastric perforation rate was 13% (95% CI, 9.4 to 17.6). Sensitivity analyses showed consistent results. Finally, publication bias was not detected. Conclusions: ESD, including endoscopic muscularis dissection, is a technically feasible procedure for the treatment of SETs. However, selection bias is suspected from the enrolled studies. For the development of a proper indication of ESD for SETs, further studies are needed.

Background/Aims: Endoscopic retrograde biliary drainage (ERBD) has become a standard procedure in patients with a biliary obstruction. Intraductal ultrasonography (IDUS) has emerged as a new tool for managing extrahepatic biliary diseases. IDUS-directed ERBD can be performed without conventional cholangiography (CC). The goal of this study was to assess the effectiveness and safety of IDUS-directed ERBD compared to CC-directed ERBD in patients with an extrahepatic biliary obstruction. Methods: A total of 210 patients who had undergone IDUS-directed ERBD (IDUS-ERBD, n = 105) and CC-directed ERBD (CC-ERBD, n = 105) between October 2013 and April 2014 were analyzed retrospectively. The primary outcome measure was the procedural success rate. Secondary outcome measures included clinical outcomes, total procedure time, radiation exposure time, and overall complication rates. Results: The total technical success rate of ERBD was 100% (105/105) in the IDUS-ERBD and CC-ERBD groups. Mean procedure time was slightly prolonged in the IDUS-ERBD group than that in the CC-ERBD group ($32.1{\pm}9.9$ minutes vs. $28.4{\pm}11.6$ minutes, p = 0.023). Mean radiation exposure time was one-third less in the IDUS-ERBD group than that in the CC-ERBD group ($28.0{\pm}49.3$ seconds vs. $94.2{\pm}57.3$ seconds, p < 0.001). No significant differences in complication rates were detected between the groups. Conclusions: IDUS-ERBD was equally effective and safe as CC-ERBD in patients with an extrahepatic biliary obstruction. Although IDUS-ERBD increased total procedure time, it significantly decreased radiation exposure.

Background/Aims: This study is a head-to-head comparison of predictive values for long-term cardiovascular outcomes between exercise electrocardiography (ex-ECG) and computed tomography coronary angiography (CTCA) in patients with chest pain. Methods: Four hundred and forty-two patients (mean age, 56.1 years; men, 61.3%) who underwent both ex-ECG and CTCA for evaluation of chest pain were included. For ex-ECG parameters, the patients were classified according to negative or positive results, and Duke treadmill score (DTS). Coronary artery calcium score (CACS), presence of plaque, and coronary artery stenosis were evaluated as CTCA parameters. Cardiovascular events for prognostic evaluation were defined as unstable angina, acute myocardial infarction, revascularization, heart failure, and cardiac death. Results: The mean follow-up duration was $2.8{\pm}1.1$ years. Fifteen patients experienced cardiovascular events. Based on pretest probability, the low- and intermediate-risks of coronary artery disease were 94.6%. Odds ratio of CACS > 40, presence of plaque, coronary stenosis ${\geq}50%$ and DTS ${\leq}4$ were significant (3.79, p = 0.012; 9.54, p = 0.030; 6.99, p < 0.001; and 4.58, p = 0.008, respectively). In the Cox regression model, coronary stenosis ${\geq}50%$ (hazard ratio, 7.426; 95% confidence interval, 2.685 to 20.525) was only significant. After adding DTS ${\leq}4$ to coronary stenosis ${\geq}50%$, the integrated discrimination improvement and net reclassification improvement analyses did not show significant. Conclusions: CTCA was better than ex-ECG in terms of predicting long-term outcomes in low- to intermediate-risk populations. The predictive value of the combination of CTCA and ex-ECG was not superior to that of CTCA alone.

Background/Aims: Neutrophil to lymphocyte ratio (NLR) in peripheral blood is a useful systemic inflammatory response biomarker. However, NLR has not been studied in patients with chronic obstructive pulmonary disease (COPD). This study was aimed to evaluate the usefulness of NLR in patients with COPD. Methods: NLR was prospectively measured and compared in patients with COPD exacerbation (n = 59), patients with stable COPD (n = 61), and healthy controls (n = 28). NLR in patients with COPD exacerbation was repeatedly measured in the convalescent period. The correlation between NLR and clinical parameters was evaluated, and the predictors for respiratory hospitalization were analyzed by multivariate logistic regression. Results: NLR values were significantly higher in patients with COPD exacerbation compared with stable COPD patients and controls ($12.4{\pm}10.6$, $2.4{\pm}0.7$, $1.4{\pm}0.5$, respectively; p < 0.001). NLR was significantly decreased during the convalescent period in patients with COPD exacerbation ($4.5{\pm}4.6$ vs. $11.5{\pm}8.8$, p < 0.001). NLR exhibited a significant correlation with the body mass index, degree of airway obstruction, dyspnea, and exercise capacity (BODE) index, the 6-minute walk test, and the modified Medical Research Council scale. NLR ${\geq}2.8$ was an independent predictor with a borderline significance for respiratory hospitalization (odds ratio, 2.083; p = 0.079). Body mass index and forced expiratory volume in 1 second were independent predictors for respiratory hospitalization. Conclusions: NLR is a straightforward and effective biomarker of COPD exacerbation that may serve as a predictor for respiratory hospitalization in patients with COPD.

Background/Aims: Osteoporosis is common in chronic obstructive pulmonary disease (COPD) patients. The relationship between osteoporosis and COPD has been primarily reported in patients with moderate to severe COPD, but there is no report in the general population. The aim of this study is to investigate the relationship between bone mineral density (BMD) and lung function in the general Korean population. Methods: This study was based on data acquired from the Fourth and Fifth Korea National Health and Nutrition Examination Surveys (KNHANES IV and V), conducted from 2008 to 2010. The study population included 4,501 subjects (aged${\geq}50$ years) who underwent both spirometry and BMD. The study populations were divided into two groups by sex to correct for the effects of gender on BMD. All female participants were postmenopausal women. Results: The BMD values of the femur neck, total femur, and L-spine tended to decrease with degree of airflow limitation in both genders. To correct confounding factors, data were analyzed and adjusted for age, body mass index, fat free mass index, body fat percentage, smoking amount, parathyroid hormone levels, daily calcium and phosphorus intake, and alkaline phosphatase (ALP) levels. While the BMD of the femur neck, total femur, and L-spine was reduced significantly as age and ALP increased, the correlation between airway obstruction and BMD of all regions disappeared in both genders. Conclusions: In the general population aged 50 years and older, diminution of BMD is not associated with airway obstruction. Further investigation along other factors is needed to determine the possible role of pulmonary function and BMD.

Background/Aims: This study examined prevalence and risk factors of periodontitis in representative samples of Korean adults, with and without diabetes mellitus (DM). Methods: Data from the 2012 Korean National Health and Nutritional Examination Survey were analyzed. A total of 4,477 adults (${\geq}30$ years old) were selected from 8,057 individuals who completed a nutrition survey, a self-reported general health behavior questionnaire, an oral examination, an oral hygiene behaviors survey, and laboratory tests. DM was defined as a fasting plasma glucose ${\geq}126mg/dL$, or self-reported diagnosed diabetes, or current use of oral hypoglycemic agents and/or insulin. The community periodontal index was used to assess periodontitis status and comparisons between the periodontitis and the non-periodontitis group, were performed, according to the presence of DM. Risk factors for periodontitis in adults with DM and without DM were evaluated by multiple logistic regression analysis. Results: The prevalence of periodontitis was significantly higher in adults with DM (43.7%) than in those without DM (25%, p < 0.001). In adults without DM, risk factors for periodontitis were older age, male, urban habitation, waist circumference, smoking, oral pain, and less frequent tooth brushing. Significant risk factors for periodontitis in adults with DM were the smoking, oral pain, and not-using an oral hygiene product. Conclusions: Adults with DM have an increased risk of periodontitis than those without DM. Current smoking and oral pain increase this risk. Using an oral hygiene product can reduce risk of periodontal disease in adults with DM.

Background/Aims: This study aimed to investigate the prevalence of chronic kidney disease (CKD) and associated risk factors in a high-risk population in Korea. Methods: A total of 6,045 participants aged ${\geq}65$ years (mean age, $73.0{\pm}5.5$) with diabetes or hypertension were enrolled. Participants were screened for CKD, which was defined as the presence of albuminuria (urine albumin-to-creatinine ratio ${\geq}30mg/g$) or an estimated glomerular filtration rate (eGFR) < $60mL/min/1.73m^2$. Results: The prevalence of CKD was 39.6% (women, 40.3%; men, 38.4%). Albuminuria was detected in 22.6% of participants, whereas eGFR < $60mL/min/1.73m^2$ was found in 24.6% of participants. The prevalence of CKD by stage was 4.4% for stage 1, 10.4% for stage 2, 23.4% for stage 3, 0.9% for stage 4, and 0.3% for stage 5. Older age, concomitant diabetes and hypertension, higher body mass index, higher systolic and diastolic blood pressure, and higher hemoglobin A1c levels were independently associated with the presence of CKD in multivariate-adjusted analyses that included with age, sex, body mass index, hypertension, diabetes, and smoking. Conclusions: The prevalence of CKD was very high in the present high-risk Korean population. Our results suggest that a screening method for early detection of CKD in high-risk populations is needed in Korea.

Background/Aims: Little is known regarding the incidence rate of and factors associated with developing chronic kidney disease after continuous renal replacement therapy (CRRT) in acute kidney injury (AKI) patients. We investigated renal outcomes and the factors associated with incomplete renal recovery in AKI patients who received CRRT. Methods: Between January 2011 and November 2013, 408 patients received CRRT in our intensive care unit. Of them, patients who had normal renal function before AKI and were discharged without maintenance renal replacement therapy (RRT) were included in this study. We examined the incidence of incomplete renal recovery with an estimated glomerular filtration rate < $60mL/min/1.73m^2$ and factors that increased the risk of incomplete renal recovery after AKI. Results: In total, 56 AKI patients were discharged without further RRT and were followed for a mean of 8 months. Incomplete recovery of renal function was observed in 20 of the patients (35.7%). Multivariate analysis revealed old age and long duration of anuria as independent risk factors for incomplete renal recovery (odds ratio [OR], 1.231; 95% confidence interval [CI], 1.041 to 1.457; p = 0.015 and OR, 1.064; 95% CI, 1.001 to 1.131; p = 0.047, respectively). In a receiver operating characteristic curve analysis, a cut-off anuria duration of 24 hours could predict incomplete renal recovery after AKI with a sensitivity of 85.0% and a specificity of 66.7%. Conclusions: The renal outcome of severe AKI requiring CRRT was poor even in patients without further RRT. Long-term monitoring of renal function is needed, especially in severe AKI patients who are old and have a long duration of anuria.

Background/Aims: Podocytes play an important role in maintaining the glomerular filtration barrier and in formation of the slit diaphragm. Podocyte loss is associated with chronic kidney disease progression, but it is not clear whether urinary podocyte proteins in urine reflect the clinical extent of glomerular damage. We investigated the correlation between the amounts of urinary podocyte proteins and renal function and albuminuria. Methods: The study enrolled 33 patients with diabetic kidney disease or glomerular disease and measured urinary podocytes proteins using Western blotting. Urinary podocyte proteins were measured according to the density of the bands on Western blotting. We measured serum creatinine and the spot urine albumin/creatinine ratio as markers of renal damage, and compared the correlation of urinary podocyte protein in the glomerular disease patients. Results: The mean patient age was $49.3{\pm}16.5years$, the mean serum creatinine level was $2.30{\pm}1.76mg/dL$, and the mean albumin/creatinine ratio was $4.85{\pm}3.52$. Among the podocyte proteins, urine synaptopodin showed strong correlation with serum creatinine by multivariate regression analysis (p < 0.001) and showed linear correlation (r = 0.429, p < 0.01). Urine podocyte proteins were increased in patients with diabetes, and synaptopodin showed the greatest significant difference ($7.68{\pm}5.61$ vs. $2.56{\pm}3.11$, p < 0.001), but this might be associated with renal impairment. The urine albumin excretion did not differ between the diabetics and non-diabetics (p = 0.73). Conclusions: Urine synaptopodin is associated with serum creatinine elevation in the patients with glomerulonephritis including diabetic kidney disease regardless of urine albumin excretion. We suggest that the urine synaptopodin level can predict glomerular damage independently of the urine albumin excretion.

Background/Aims: Recently, large cohort studies regarding associations between autoimmune disease and lymphomas have been reported in a few Western countries. However, Asian data concerning autoimmune-related lymphomas are limited. Therefore, we evaluated the clinical characteristics and prognostic factors of patients with autoimmune disease-related non-Hodgkin lymphoma (NHL) in a single center in Korea. Methods: We analyzed the data from 11 patients with autoimmune-related NHL. Patients were categorized into two groups, those with rheumatoid arthritis (RA) and those with non-RA-related NHL. Then patients were re-categorized into a group with methotrexate (MTX) usage and a MTX non-usage group. Histological subtype, MTX duration, autoimmune disease duration, treatment modalities, and other data were collected and analyzed. Results: Our study revealed that older RA patients have a greater likelihood of occurrence of NHL (p = 0.042). We confirmed that MTX duration and cumulative dose of MTX have no significant correlation with autoimmune disease and NHL (p = 0.073). In the management of autoimmune disease-related NHL, all patients were directly treated with systemic chemotherapy instead of employing a wait and watch approach. Overall survival (OS) and progression-free survival (PFS) in all autoimmune disease-related NHL were 100% and 87.5%, with no treatment-related mortality during the 2-year follow-up period of our study. Conclusions: Our study suggests that patients with RA-NHL are characterized by older age at onset compared to those with non-RA-NHL. Also considering of OS and PFS, intensive treatment strategy instead of delayed watchful managements may be required for autoimmune disease-related NHL including of old age group.

Background/Aims: The frequencies of opportunistic diseases (ODs) vary across countries based on genetic, environmental, and social differences. The Korean HIV/AIDS cohort study was initiated in 2006 to promote research on human immunodeficiency virus (HIV) infection in Korea, and to provide a logistical network to support multicenter projects on epidemiological, clinical, and laboratory aspects of HIV infection. This study evaluated the prevalence of ODs among HIV-infected patients in the era of highly active antiretroviral therapy, and the risk factors associated with ODs. Methods: The study enrolled 1,086 HIV-infected patients from 19 hospitals. This study examined the baseline data of the HIV/AIDS Korean cohort study at the time of enrollment from December 2006 to July 2013. Results: Candidiasis was the most prevalent opportunistic infection (n = 176, 16.2%), followed by Mycobacterium tuberculosis infection (n = 120, 10.9%), Pneumocystis jirovecii pneumonia (n = 121, 11.0%), cytomegalovirus infection (n = 52, 4.7%), and herpes zoster (n = 44, 4.0%). The prevalence rates of Kaposi's sarcoma (n = 8, 0.7%) and toxoplasmosis (n = 4, 0.4%) were very low compared with other countries. The risk factors for ODs were a low CD4 T cell count at the time of HIV diagnosis (odds ratio [OR], 1.01; p < 0.01), current smoking (OR, 2.27; p = 0.01), current alcohol use (OR, 2.57; p = 0.04), and a history of tuberculosis (OR, 5.23; p < 0.01). Conclusions: Using recent Korean nationwide data, this study demonstrated that an important predictor of ODs was a low CD4 T cell count at the time of HIV diagnosis. Tuberculosis remains one of the most important ODs in HIV-infected patients in Korea.

Background/Aims: Cytomegalovirus (CMV) surveillance and preemptive therapy is a widely-used strategy for preventing CMV disease in transplant recipients. However, there are limited data on the incidence and patterns of CMV disease during the preemptive period. Thus, we investigated the incidence and pattern of tissue-invasive CMV disease in CMV seropositive kidney transplantation (KT) and hematopoietic stem cell transplantation (HCT) recipients during preemptive therapy. Methods: We prospectively identified patients with tissue-invasive CMV disease among 664 KT (90%) and 496 HCT (96%) recipients who were D+/R+ (both donor and recipient seropositive) during a 4-year period. Results: The incidence rates of CMV disease were 4.1/100 person-years (4%, 27/664) in KT recipients and 5.0/100 person-years (4%, 21/496) in HCT recipients. Twenty-six (96%) of the KT recipients with CMV disease had gastrointestinal CMV, whereas 17 (81%) of the HCT recipients had gastrointestinal CMV and 4 (19%) had CMV retinitis. Thus, CMV retinitis was more common among HCT recipients (p = 0.03). All 27 KT recipients with CMV disease suffered abrupt onset of CMV disease before or during preemptive therapy; 10 (48%) of the 21 HCT recipients with CMV disease were also classified in this way but the other 11 (52%) were classified as CMV disease following successful ganciclovir preemptive therapy (p < 0.001). Conclusions: The incidence of CMV disease was about 4% in both KT and HCT recipients during preemptive therapy. However, CMV retinitis and CMV disease as a relapsed infection were more frequently found among HCT recipients.

Background/Aims: We aimed to investigate the prevalence and possible causes of hypouricemia in the Korean population and to compare our findings with published results of other populations. Methods: We examined the serum uric acid levels of 30,757 subjects who had their uric acid values measured at least once during a 1-year period. All individuals with hypouricemia (serum uric acid < 2.0 mg/dL, n = 424) were reviewed with respect to medical drug history and concomitant diseases previously identified as being associated with hypouricemia. Results: The prevalence of hypouricemia was 4.14% (299/7,223) among inpatients and 0.53% (125/23,534) among outpatients, for an overall prevalence of 1.39% (424/30,757). Possible causes associated with hypouricemia were found to be solid or hematologic malignancies (n = 86), diabetes mellitus (n = 56), and therapeutic drugs (n = 29). The medications were allopurinol (n = 11), angiotensin II receptor blockers (n = 10), salicylates (n = 6), febuxostat (n = 1), and warfarin (n = 1). In the remaining 226 individuals, the cause of hypouricemia was not identified. Conclusions: Hypouricemia is relatively common in the Korean population compared to those of other countries. The possible causes associated with hypouricemia are related to underlying diseases and medications.

Background/Aims: A cross-sectional study was undertaken to investigate the association between severity of periodontitis and clinical manifestation of rheumatoid arthritis (RA). Methods: Two hundred sixty-four RA patients and 88 age- and sex-matched controls underwent dental exam. Additionally, clinical manifestations including disease activity and anti-citrullinated protein antibodies were evaluated in RA patients. Results: The prevalence of moderate or severe periodontitis was higher in RA patients compared to controls (63.6% vs 34.1%, p < 0.001). In markers of periodontal inflammation, bleeding on probing was correlated with disease activity score 28 (r = 0.128, p = 0.041), RA disease duration (r = 0.211, p = 0.001), erythrocyte sedimentation rate (ESR; r = 0.141, p = 0.023), anti-cyclic citrullinated peptide antibody (r = 0.183, p = 0.009), and anti-citrullinated ${\alpha}$-enolase peptide-1 antibody (r = 0.143, p = 0.025). Gingival index was correlated with RA duration (r = 0.262, p < 0.001), ESR (r = 0.162, p = 0.009), anti-cyclic citrullinated peptide antibody (r = 0.203, p = 0.004) and anti-citrullinated ${\alpha}$-enolase peptide-1 antibody (r = 0.225, p < 0.001). Periodontal structural damage represented by probing pocket depth and clinical attachment level were less in RA patients with human leukocyte antigen (HLA)-DRB1 shared epitope compared than those without shared epitope (p = 0.005 and p =0.006, respectively). Conclusions: The prevalence of moderate or severe periodontitis was increased in RA patients compared to controls. Periodontal inflammation was correlated with RA disease duration, ESR, and anti-citrullinated protein antibodies. Periodontal structural damage was less in RA patients with HLA-DRB1 shared epitope.