Purpose: Clinically, breast cancer can be divided into 4 subtypes based on the presence of hormone receptors, human epidermal growth factor receptor 2 (HER2), and Ki-67. Because the pattern and time of recurrence vary according to the subtype, we evaluated whether there was a difference in overall survival (OS) among the subtypes according to the time and type of recurrence. Methods: A total of 2,730 patients who underwent breast cancer surgery were analyzed. Early and late recurrence were defined as recurrence within and after 5 years of diagnosis, respectively. Recurrence type was categorized as locoregional recurrence or systemic recurrence. Results: Hormone receptor-positive tumors were significantly more frequent in the late recurrence group than in the early recurrence group (estrogen receptor positive, 47.8% [early] vs. 78.7% [late]). However, there was no difference in the rate of HER2 overexpression (HER2+, 38.1% [early] vs.39.0% [late]). In subgroup analysis, early recurrence was a significant prognostic factor for OS in all subtypes. However, late recurrence was a significant prognostic factor for OS only in the luminal B subtype (hazard ratio of 4.30). In addition, the luminal B type had the highest proportion in late recurrence patients (63.2%). Conclusion The luminal B subtype had a high rate of late recurrence, and late recurrence was a poor prognostic factor for OS only in this subgroup. Therefore, further targeted treatments for luminal B breast cancer are needed and patients with this subtype require close long-term surveillance.

Purpose: The purpose of this study was to develop a Korean Adult Patients Delirium Screening Tool (K-APDS) for those admitted to general wards, and to verify its reliability and validity. Methods: For the development of the tool, 12 items were derived through the results of literature review and focus group interviews with general ward nurses, and the content validity was confirmed by experts. To verify the reliability and validity of the developed tool, 317 adult patients who were admitted to general wards of three tertiary general hospitals from October to November 2022 were evaluated by the attending nurse and data were collected. Results: After factor analysis for construct validity verification, two factors were extracted, which explained 60.1% of the total variance. After the validation of the control group, the difference in the delirium incidence scores calculated using the K-APDS between the delirium group and non-delirium group was very significant (Z=-10.82, p<.001).To verify the criterion validity, K-APDS, Delirium Observation Screening, and Pearson's correlation coefficient were checked and found to be .94 (p<.001). The predictive validity test reported that the sensitivity was 91.1%, specificity was 82.4%, positive predictive value was 52.6%, and negative predictive value was 97.8%. The reliability of K-APDS was found to be high with Cronbach’s ⍺=.91. Conclusion K-APDS can screen for delirium with 2 or more points, excellent validity and reliability have been verified. Therefore, this tool could be applied immediately in the clinical field, and will contribute to the early detection of delirium, enabling rapid interventions.

Background: This study aimed to investigate perceptions of Clostridioides difficile infection (CDI) diagnostic tests among physicians who prescribe CDI diagnostic tests as part of providing direct patient care. Methods: In August 2018, we provided a 12-question survey of gastroenterologists (the most common referral source for CDI testing) to 35 medical institutions in Korea, asking them about their perceptions of CDI diagnosis and testing. Results: A comparison of the perceptions of physicians and clinical pathologists (CPs) found that physicians had a lower perceived sensitivity of the toxin AB enzyme immunoassay test. For nucleic acid amplification tests, physicians exhibited a perception of higher assay sensitivity and specificity than CPs. The specificity of culture tests was generally perceived as high by physicians, whereas CPs regarding expressed mixed opinions. All but one physician and one CPs found the algorithmic test useful. Concerning the CDI isolation criteria, physicians commenced patient isolation by concurrently assessing both test results and clinical symptoms, rather than exclusively relying upon test results. Among CPs, 84.6% said they could rely on symptoms to determine when to release a patient from isolation, while 46.2% of physicians said they would rely on test results. Conclusion This study provides useful information on the status of laboratory diagnosis of CDI in Korea and what needs to be improved, which will help to standardize and improve laboratory diagnosis of CDI in Korea.

Purpose: Although adjuvant chemotherapy (CTx) is still recommended for high-risk patients with hormone receptorpositive and human epidermal receptor (HER)-2-negative breast cancer, recent studies found that selected patients with low disease burden may be spared from CTx and receive hormonal treatment (HT) alone. This study aims to evaluate the trends of treatment (CTx + HT vs. HT alone) in Korea and to assess the impact on overall survival (OS) according to treatment pattern. Methods: The Korean Breast Cancer Society Registry was queried (2000 to 2018) for women with pT1-2N0-1 hormone receptor-positive and HER2-negative disease who underwent surgery and adjuvant systemic treatment (CTx and HT). Clinicopathologic factors, change in pattern of treatment over time, and OS for each treatment option were analyzed. Results: A total of 40,938 women were included in the study; 20,880 (51.0%) received CTx + HT, while 20,058 (49.0%) received HT only. In recent years, there has been a steady increase in the use of HT alone, from 21.0% (2000) to 64.6% (2018). In Cox regression analysis, age, type of breast and axillary operations, T and N stages, body mass index, histologic grade,and presence of lymphovascular invasion were prognostic indicators for OS. There was no significant difference between CTx + HT and HT alone in terms of OS (P = 0.126). Conclusion Over the years, there has been a shift from CTx + HT to HT alone without a significant difference in OS. Therefore, HT alone could be a safe treatment option in selected patients, even those with T2N1 disease.

Purpose: Although protein-induced vitamin K absence or antagonist II (PIVKA-II) has been used as a diagnostic tool for hepatocellular carcinoma (HCC), its prognostic value remains unclear. Methods: This was a nationwide multicenter study using the database of the Korean Liver Cancer Association. Patients with hepatitis B-related HCC who underwent liver resection as the first treatment after initial diagnosis (2008–2014) were selected randomly. Propensity score matching (1:1) was performed for comparative analysis between those with low and high preoperative PIVKA-II. Univariable and multivariable Cox proportional-hazards regression were used to identify prognostic factors for HCC-specific survival. Results: Among 6,770 patients, 956 patients were included in this study. After propensity score matching, the 2 groups (n = 245, each) were well balanced. The HCC-specific 5-year survival rate was 80.9% in the low PIVKA-II group and 78.7% in the high PIVKA-II group (P = 0.605). In univariable analysis, high PIVKA-II (>106.0 mAU/mL) was not a significant predictor for worse HCC-specific survival (hazard ratio [HR], 1.183; 95% confidence interval [CI], 0.76–1.85; P = 0.461). In multivariable analysis, hyponatremia of <135 mEq/L (HR, 4.855; 95% CI, 1.67–14.12; P = 0.004), preoperative ascites (HR, 4.072; 95% CI, 1.59–10.43; P = 0.003), microvascular invasion (HR, 3.112; 95% CI, 1.69–5.74; P < 0.001), and largest tumor size of ≥5.0 cm (HR, 2.665; 95% CI, 1.65–4.31; P < 0.001), but not preoperative high PIVKA-II, were independent predictors for worse HCCspecific survival. Conclusion Preoperative PIVKA-II is not an independent prognostic factor for HCC-specific survival after liver resection for hepatitis B-related HCC.

Background/Aims: The prospective Crohn’s Disease Clinical Network and Cohort Study is a nationwide multicenter cohort study of patients with Crohn’s disease (CD) in Korea, aiming to prospectively investigate the clinical features and long-term prognosis associated with CD. Methods: Patients diagnosed with CD between January 2009 and September 2019 were prospectively enrolled. They were divided into two cohorts according to the year of diagnosis: cohort 1 (diagnosed between 2009 and 2011) versus cohort 2 (between 2012 and 2019). Results: A total of 1,175 patients were included, and the median follow-up duration was 68 months (interquartile range, 39.0 to 91.0 months). The treatment-free durations for thiopurines (p<0.001) and anti-tumor necrosis factor agents (p=0.018) of cohort 2 were shorter than those of cohort 1. Among 887 patients with B1 behavior at diagnosis, 149 patients (16.8%) progressed to either B2 or B3 behavior during follow-up. Early use of thiopurine was associated with a reduced risk of behavioral progression (adjusted hazard ratio [aHR], 0.69; 95% confidence interval [CI], 0.50 to 0.90), and family history of inflammatory bowel disease was associated with an increased risk of behavioral progression (aHR, 2.29; 95% CI, 1.16 to 4.50). One hundred forty-one patients (12.0%) underwent intestinal resection, and the intestinal resection-free survival time was significantly longer in cohort 2 than in cohort 1 (p=0.003). The early use of thiopurines (aHR, 0.35;95% CI, 0.23 to 0.51) was independently associated with a reduced risk of intestinal resection. Conclusions The prognosis of CD in Korea appears to have improved over time, as evidenced by the decreasing intestinal resection rate. Early use of thiopurines was associated with an improved prognosis represented by a reduced risk of intestinal resection.

Background/Aims: There is a recent increase in the use of stool multiplex PCR assay-based diagnostic tests in patients with acute diarrhea. We used multiplex PCR assays to analyze the distribution of diarrhea-causing bacteria and viruses, as well as the clinical features of patients with acute diarrhea. Methods: We retrospectively reviewed stool specimens of inpatients complaining of acute diarrhea from October 2018 to July 2020.The stool specimens had been tested for bacteria and viruses using multiplex PCR assays. Results: A total of 414 stool specimens from 346 patients were tested, and 152 pathogens were detected in 131 stool samples (131/414, 31.6%). Co-infection was detected in 20 patients (20/346, 5.8%). The common pathogens detected as causes of acute diarrhea, including co-infection, were Clostridium perfringens (34.9%), Clostridioides difficile (19.7%), and Campylobacter spp. (18.4%). The average age of patients with multiplex PCR-positive tests was lower than those with multiplex PCR-negative tests (p=0.001). In patients with suspected C. difficile infection (CDI), the RT-PCR for toxin gene assay was performed in 370 stool samples, 35 of which were positive (9.5%). Furthermore, 16 of the 35 samples were positive on the multiplex PCR assay (45.7%). Conclusions The multiplex PCR assay revealed that C. perfringens was the most common diarrhea-causing pathogen. In addition, in patients with suspected CDI, the multiplex PCR assay alone was insufficiently sensitive to detect pathogens and a conventional CDI test was additionally required.

Background: The interest in Clostridioides difficile infection (CDI) has increased, and the choice of assays became wider since the first national survey in Korea on CDI diagnosis in 2015. We conducted a survey of the domestic CDI assays with more varied questions to understand the current situation in Korea. Methods: In April 2018, about 50 questions on the current status of CDI assays and details on implementation and perceptions were written, and a survey questionnaire was administered to laboratory medicine specialists in 200 institutions. Results: One-hundred and fifty institutions responded to the questionnaire, of which 90 (60.0%) including one commercial laboratory, performed CDI assays. The toxin AB enzyme immunoassay (toxin AB EIA), nucleic acid amplification test (NAAT), and C. difficile culture, glutamate dehydrogenase assay, alone or in combination with other assays, were used in 75 (84.3%), 52 (58.4%), 35 (36.0%), and 23 (25.8%), respectively, and 65 (73.0%) institutions performed a combination of two or more assays. The sensitivity of toxin AB EIA was more negatively perceived, and that on specificity was more positively perceived. The perception of sensitivity and specificity of NAAT was mostly positive. Perception on the algorithm test projected it as useful but in need of countermeasures. Sixty-three (73.3%) institutions responded that they performed surveillance on CDI. Conclusion This study provides useful evidence on the current status of CDI laboratory diagnosis in Korea as well as on items that require improvement and is thought to aid in standardizing and improving the CDI laboratory diagnosis in Korea.

Background/Aims: This study assessed the efficacy and safety of adalimumab (ADA) and explored predictors of response in Korean patients with ulcerative colitis (UC). Methods: A prospective, observational, multicenter study was conducted over 56 weeks in adult patients with moderately to severely active UC who received ADA. Clinical response, remission, and mucosal healing were assessed using the Mayo score. Results: A total of 146 patients were enrolled from 17 academic hospitals. Clinical response rates were 52.1% and 37.7% and clinical remission rates were 24.0% and 22.0% at weeks 8 and 56, respectively. Mucosal healing rates were 39.0% and 30.1% at weeks 8 and 56, respectively. Prior use of anti-tumor necrosis factor-α (anti-TNF-α) did not affect clinical and endoscopic responses. The ADA drug level was significantly higher in patients with better outcomes at week 8 (P<0.05). In patients with lower endoscopic activity, higher body mass index, and higher serum albumin levels at baseline, the clinical response rate was higher at week 8. In patients with lower Mayo scores and C-reactive protein levels, clinical responses, and mucosal healing at week 8, the clinical response rate was higher at week 56. Serious adverse drug reactions were identified in 2.8% of patients. Conclusions ADA is effective and safe for induction and maintenance in Korean patients with UC, regardless of prior anti-TNF-α therapy. The ADA drug level is associated with the efficacy of induction therapy. Patients with better short-term outcomes were predictive of those with an improved long-term response.

Background/Aims: Nutritional status influences quality of life among patients with inflammatory bowel disease (IBD), although there is no clear method to evaluate nutritional status in this setting. Therefore, this study examined whether bioelectrical impedance analysis (BIA) could be used to evaluate the nutritional status of patients with IBD. Methods: We retrospectively analyzed data from 139 Korean patients with IBD who were treated between November 2018 and November 2019. Patients were categorized as having active or inactive IBD based on the Harvey-Bradshaw index (a score of ≥5 indicates active Crohn’s disease) and the partial Mayo scoring index (a score of ≥2 indicates active ulcerative colitis). BIA results and serum nutritional markers were analyzed according to disease activity. Results: The mean patient age was 45.11±17.71 years. The study included 47 patients with ulcerative colitis and 92 patients with Crohn’s disease. Relative to the group with active disease (n=72), the group with inactive disease (n=67) had significantly higher values for hemoglobin (P<0.001), total protein (P<0.001), and albumin (P<0.001). Furthermore, the group with inactive disease had higher BIA values for body moisture (P=0.047), muscle mass (P=0.046), skeletal muscle mass (P=0.042), body mass index (P=0.027), and mineral content (P=0.034). Moreover, the serum nutritional markers were positively correlated with the BIA results. Conclusions Nutritional markers evaluated using BIA were correlated with serum nutritional markers and inversely correlated with disease activity. Therefore, we suggest that BIA may be a useful tool that can help existing nutritional tests monitor the nutritional status of IBD patients.