This study aimed to determine the prevalence of human epidermal growth factor receptor 2 (HER2)–ultralow breast cancer among cases initially classified as HER2 immunohistochemistry (IHC) 0 and assess interobserver variability in interpreting low-level HER2 expression. Methods: In this multicenter retrospective study, all invasive breast cancer cases diagnosed between January and December 2022 across 10 Korean institutions were retrieved. Institutional pathologists reexamined HER2 IHC slides originally reported as IHC 0 according to the 2018 American Society of Clinical Oncology/College of American Pathologists guidelines and reclassified them as HER2-null (0), HER2-ultralow (0+), or HER2-low (1+). Slides from 10% of HER2-null and HER2-ultralow cases were digitized for central review and independently assessed by two pathologists, with discrepancies resolved by consensus. Results: Among 8,026 cases, 2,836 cases (35.5%) were initially reported as IHC 0. Upon re-review, 1,673 (59.0%), 1,139 (40.2%), and 24 (0.8%) cases were reclassified as HER2-null, HER2-ultralow, and HER2-low, respectively. The prevalence of HER2-ultralow breast cancer varied considerably across institutions (23.7%–78.1%). Central review of 268 digitized cases showed concordance in 193 cases (72.0%). Among the 75 discordant cases, 54 tumors (72.0%) were upgraded from HER2-null to HER2-ultralow, and 18 (24.0%) tumors were upgraded from HER2-ultralow to HER2-low. Furthermore, two tumors (2.7%) were downgraded from HER2-ultralow to HER2-null. Conclusions: Approximately 40% of cases initially categorized as IHC 0 were reclassified as HER2-ultralow. The substantial inter-institutional variability observed in interpreting low-level HER2 expression highlights the need for standardized training and quality assurance to ensure accurate identification of patients eligible for HER2-targeted antibody–drug conjugates.

Objectives: Assessing healthcare quality at the national level is essential for evaluating health system performance and identifying areas requiring improvement. This study examined long-term trends in healthcare quality in Korea from 2008 to 2023 using internationally comparable indicators. Methods: We conducted a trend analysis of healthcare quality in Korea using the Organization for Economic Cooperation and Development (OECD) Health Care Quality and Outcomes framework and quality indicators. Indicators across multiple domains, including acute care, primary care, prescribing in primary care, mental healthcare, and patient experiences, were analyzed and compared with OECD averages. Results: Healthcare quality in Korea improved across several domains. Thirty-day mortality for acute myocardial infarction decreased from 14.2% in 2008 to 10.2% in 2023, while mortality for ischemic stroke declined from 8.7% to 5.5%. Avoidable hospitalizations decreased substantially, with hospitalizations for chronic obstructive pulmonary disease declining by 59.7%. The proportion of patients with diabetes receiving cholesterol-lowering treatment increased from 44.1% to 82.5%. However, the proportion of broad-spectrum antibiotic prescriptions remained substantially higher than the OECD average (40.3 vs. 15.5%). In mental healthcare, excess mortality ratios increased from 4.3 in 2010 to 4.9 in 2023 for schizophrenia and from 3.5 to 4.3 for bipolar disorder, while post-discharge suicide rates showed little improvement. Patient experience indicators related to patient-physician communication improved and approached OECD averages. Conclusions Healthcare quality in Korea improved substantially between 2008 and 2023, particularly in acute care outcomes and chronic disease management. However, persistent challenges remain in areas such as antibiotic use, polypharmacy, and mental healthcare. These findings provide internationally comparable evidence to inform future health policy and healthcare quality improvement efforts.

Purpose: Previous studies from mostly Western populations have suggested possible associations between obesity and melanoma risk. This study aimed to investigate associations between obesity status and melanoma using a nationwide cohort of Koreans. Materials and Methods: A total of 4,441,403 adults who received a national health examination in 2012 were included from the Korean National Health Insurance Service database, and followed until December 31, 2022. Obesity status was defined based on the body mass index at the baseline health examination. Cox proportional hazards analyses were performed to evaluate associations between obesity status and incident melanoma, with adjustment for confounders. Stratified analyses were performed by sex and menopausal status (in women). Results: Overall, melanoma risk increased according to obesity status (p for trend=0.024); adjusted hazard ratios (95% confidence intervals) for melanoma risk were 0.766 (0.438–1.340) in underweight; 1.292 (1.072–1.557) in overweight; 1.202 (1.002–1.442) in obesity; and 1.191 (0.798–1.778) in severe obesity compared to normal weight (reference). In stratified analyses, similar trends to those of the overall study population were observed among men and premenopausal women (p for trend=0.052 in men and 0.036 in premenopausal women). Among premenopausal women, the risk of melanoma increased linearly with obesity status. Meanwhile, among postmenopausal women, melanoma risk showed no significant difference or trend according to obesity status. Conclusion Overweight and obesity were associated with increased risk of melanoma in a population-based cohort of Koreans. Obese individuals, especially men and premenopausal women, may require more thorough prevention and screening strategies for melanoma.

Purpose: The aim of this study is to compare the detection ability of quality of life (QoL) changes and responsiveness of the KOrean QUality of life in Stomach cancer patients Study group (KOQUSS)-40 and European Organization for Research and Treatment of Cancer Quality of Life Questionnaire (EORTC QLQ). Materials and Methods: A multicenter prospective observational study was conducted to evaluate QoL changes after various gastrectomies between January 2021 and April 2022. Participants were instructed to complete the KOQUSS-40 and EORTC QLQ-C30/STO22 preoperatively and at 1, 3, 6, and 12 months postoperatively. QoL changes over time and QoL responsiveness were assessed for each questionnaire. Results: Data from 491 patients who underwent curative gastrectomy for gastric cancer at 22 institutions were analyzed. The summary scores of the KOQUSS-40 and EORTC QLQ-STO22 showed significant differences between the total and proximal gastrectomy groups (p=0.044 and p=0.038, respectively), but no difference was observed for the EORTC QLQ-C30. Dysphagia on the KOQUSS-40 was significantly different between the total and proximal gastrectomy groups (p=0.031); however, dysphagia on the EORTC QLQ-STO22 did not differ. The responsiveness of the KOQUSS-40 was similar to that of the EORTC QLQ in patients who experienced ≥ 10% body weight loss, but approximately 10% less in patients receiving adjuvant chemotherapy than the EORTC QLQ. Conclusion KOQUSS-40 has several advantages over EORTC QLQ-C30/STO22 when comparing QoL between the total and proximal gastrectomy groups. The findings provide information for researchers investigating the QoL of patients who have undergone curative gastrectomy for gastric cancer.

Objective: Medication adherence is crucial for long-term outcomes in bipolar disorder. Despite the rising use of aripiprazole, a longacting injectable for bipolar disorder, once monthly to improve adherence and manage side effects, research on its effects in South Korean patients with bipolar disorder is limited. Methods: In this non-interventional, retrospective study, medical records were used to analyze aripiprazole once monthly treatment from its initiation in routine clinical settings. The data were collected at 1, 3, 6, 9, and 12 months. Functional level and symptom severity were measured using the Global Assessment of Functioning (GAF), Clinical Global Impression–Bipolar–Severity (CGI-BP-S), Young Mania Rating Scale (YMRS), Korean version of the Montgomery–Åsberg Depression Rating Scale (K-MADRS), and Hamilton Anxiety Rating Scale (HAM-A). Additionally, the dosages and number of pills of mood stabilizers and antipsychotics, and the total number of medications, were recorded. Results: Among 24 patients with bipolar disorder, significant functional improvement and symptom relief were observed over 1 year, with a significant reduction in total pill count and dosages of mood stabilizers and antipsychotics. Specifically, the GAF score increased by 25.7% (p=0.001), while CGI-BP-S, YMRS, K-MADRS, and HAM-A scores decreased by 24.4% (p=0.001), 81.2% (p=0.001), 36.2% (p=0.002), and 36.1% (p=0.003), respectively. Six patients reported side effects such as akathisia, tremors, weight gain, and headache, but no severe adverse effects were noted. Conclusion This study showed significant improvement in functional outcomes and mood symptoms with monthly aripiprazole treatment in bipolar disorder. Mood stabilizer and antipsychotic dosages were also reduced. The results highlight the proactive role of longacting injectable antipsychotics in enhancing functioning, symptoms, and quality of life in bipolar disorder.

Purpose: This study aimed to examine changes in nurse staffing grades and nursing fee revenues in intensive care units (ICUs) following the third amendment of the resource-based relative value scale, which was implemented in January 2024. Methods: Changes in staffing grades from the fourth quarter of 2023 to the first quarter of 2024 were analyzed among 588 general ICUs, 94 neonatal ICUs, and 13 pediatric ICUs. Annual nursing fee revenues per nurse were estimated based on the new nursing fee structure for each grade. Results: In general ICUs, the highest grade (grade S) and the second-highest grade (grade A) accounted for 7.3% and 41.5%, respectively, in tertiary hospitals, whereas 3.8% were grade S and 11.5% were grade A in general hospitals. In neonatal ICUs, the proportion of higher grades (S, A, and 1) was greater in general hospitals (54.3%) than in tertiary hospitals (38.6%). In pediatric ICUs, 30.8% were grade S and 61.5% were grade A. When applying the same grading criteria (i.e., beds per nurse) across both quarters, staffing levels remained unchanged in most ICUs. Nursing fees and their revenues did not increase proportionally to staffing requirements (i.e., the number of nurses required per patient). Conclusion Revisions to staffing grade and nursing fee systems are necessary to induce medical institutions to improve their ICU staffing levels.

Purpose: This study aimed to examine changes in nurse staffing grades and nursing fee revenues in intensive care units (ICUs) following the third amendment of the resource-based relative value scale, which was implemented in January 2024. Methods: Changes in staffing grades from the fourth quarter of 2023 to the first quarter of 2024 were analyzed among 588 general ICUs, 94 neonatal ICUs, and 13 pediatric ICUs. Annual nursing fee revenues per nurse were estimated based on the new nursing fee structure for each grade. Results: In general ICUs, the highest grade (grade S) and the second-highest grade (grade A) accounted for 7.3% and 41.5%, respectively, in tertiary hospitals, whereas 3.8% were grade S and 11.5% were grade A in general hospitals. In neonatal ICUs, the proportion of higher grades (S, A, and 1) was greater in general hospitals (54.3%) than in tertiary hospitals (38.6%). In pediatric ICUs, 30.8% were grade S and 61.5% were grade A. When applying the same grading criteria (i.e., beds per nurse) across both quarters, staffing levels remained unchanged in most ICUs. Nursing fees and their revenues did not increase proportionally to staffing requirements (i.e., the number of nurses required per patient). Conclusion Revisions to staffing grade and nursing fee systems are necessary to induce medical institutions to improve their ICU staffing levels.

Purpose: This study evaluated the postoperative quality of life (QoL) after various types of gastrectomy for gastric cancer. Materials and Methods: A multicenter prospective observational study was conducted in Korea using the Korean Quality of Life in Stomach Cancer Patients Study (KOQUSS)-40, a new QoL assessment tool focusing on postgastrectomy syndrome. Overall, 496 patients with gastric cancer were enrolled, and QoL was assessed at 5 time points: preoperatively and at 1, 3, 6, and 12 months after surgery. Results: Distal gastrectomy (DG) and pylorus-preserving gastrectomy (PPG) showed significantly better outcomes than total gastrectomy (TG) and proximal gastrectomy (PG) with regard to total score, indigestion, and dysphagia. DG, PPG, and TG also showed significantly better outcomes than PG in terms of dumping syndrome and worry about cancer. Postoperative QoL did not differ significantly according to anastomosis type in DG, except for Billroth I anastomosis, which achieved better bowel habit change scores than the others. No domains differed significantly when comparing double tract reconstruction and esophagogastrostomy after PG. The total QoL score correlated significantly with postoperative body weight loss (more than 10%) and extent of resection (P<0.05 for both).Reflux as assessed by KOQUSS-40 did not correlate significantly with reflux observed on gastroscopy 1 year postoperatively (P=0.064). Conclusions Our prospective observation using KOQUSS-40 revealed that DG and PPG lead to better QoL than TG and PG. Further study is needed to compare postoperative QoL according to anastomosis type in DG and PG.

Background: Colorectal carcinomas (CRCs) with caudal-type homeobox 2 (CDX2) loss are recognized to pursue an aggressive behavior but tend to be accompanied by a high density of tumor-infiltrating lymphocytes (TILs). However, little is known about whether there is an interplay between CDX2 loss and TIL density in the survival of patients with CRC. Methods: Stage III CRC tissues were assessed for CDX2 loss using immunohistochemistry and analyzed for their densities of CD8 TILs in both intraepithelial (iTILs) and stromal areas using a machine learning-based analytic method. Results: CDX2 loss was significantly associated with a higher density of CD8 TILs in both intraepithelial and stromal areas. Both CDX2 loss and a high CD8 iTIL density were found to be prognostic parameters and showed hazard ratios of 2.314 (1.050–5.100) and 0.378 (0.175–0.817), respectively, for cancer-specific survival. A subset of CRCs with retained CDX2 expression and a high density of CD8 iTILs showed the best clinical outcome (hazard ratio of 0.138 [0.023–0.826]), whereas a subset with CDX2 loss and a high density of CD8 iTILs exhibited the worst clinical outcome (15.781 [3.939–63.230]). Conclusions Altogether, a high density of CD8 iTILs did not make a difference in the survival of patients with CRC with CDX2 loss. The combination of CDX2 expression and intraepithelial CD8 TIL density was an independent prognostic marker in adjuvant chemotherapy-treated patients with stage III CRC.

Background: Intellectual disability (ID) may be associated with an increased risk of diabetes mellitus (DM). However, evidence from longitudinal studies is scarce, particularly in Asian populations. Methods: This retrospective cohort study used representative linked data from the Korea National Disability Registration System and the National Health Insurance Service database. Adults (≥20 years) who received a national health examination in 2009 (3,385 individuals with ID and 3,463,604 individuals without ID) were included and followed until 2020. ID was identified using legal registration information. Incident DM was defined by prescription records with relevant diagnostic codes. Multivariable-adjusted Cox proportional hazards regression models were used to estimate the adjusted hazard ratio (aHR) and 95% confidence interval (CI) for DM risks in individuals with ID compared to those without ID. Results: Over a mean follow-up of 9.8 years, incident DM occurred in 302 (8.9%) individuals with ID and 299,156 (8.4%) individuals without ID. Having ID was associated with increased DM risk (aHR, 1.38; 95% CI, 1.23 to 1.55). Sensitivity analysis confirmed a higher DM risk in individuals with ID (aHR, 1.39; 95% CI, 1.24 to 1.56) than those with other disabilities (aHR, 1.11; 95% CI, 1.10 to 1.13) or no disability (reference). Stratified analysis showed higher DM risk in non-hypertensive subjects (aHR, 1.63; 95% CI, 1.43 to 1.86) compared to hypertensive subjects (aHR, 1.00; 95% CI, 0.80 to 1.26; P for interaction <0.001). Conclusion Adults with ID have an increased risk of developing DM, highlighting the need for targeted public health strategies to promote DM prevention in this population.