OBJECTIVES: Breast cancer is the second most common cancer among Korean women. Because breast cancer is strongly associated with negative emotional and physical changes, early detection and treatment of breast cancer are very important. As a supporting tool for classifying breast cancer, we tried to identify the best meta-learner model in a stacking ensemble when the same machine learning models for the base learner and meta-learner are used. METHODS: We used machine learning models, such as the gradient boosted model, distributed random forest, generalized linear model, and deep neural network in a stacking ensemble. These models were used to construct a base learner, and each of them was used as a meta-learner again. Then, we compared the performance of machine learning models in the meta-learner to determine the best meta-learner model in the stacking ensemble. RESULTS: Experimental results showed that using the GBM as a meta-learner led to higher accuracy than that achieved with any other model for breast cancer data and using the GLM as a meta learner led to low root-mean-squared error for both sets of breast cancer data. CONCLUSIONS: We compared the performance of every meta-learner model in a stacking ensemble as a supporting tool for classifying breast cancer. The study showed that using specific models as a metalearner resulted in better performance than single classifiers, and using GBM and GLM as a meta-learner is appropriate as a supporting tool for classifying breast cancer data.
Breast Neoplasms ; Breast ; Classification ; Female ; Forests ; Humans ; Linear Models ; Machine Learning ; Medical Informatics ; Statistics as Topic

Objective: The purpose of the study was to analyze triage re-evaluation characteristics of the Korean Triage and Acuity Scale (KTAS). In particular, the relationship between overcrowding and KTAS re-evaluation at the emergency department (ED) was analyzed. Methods: In this study, a retrospective chart review of 3,158 KTAS re-evaluation cases was performed. The sample included patients visiting a regional ED from January 1 to December 31 in 2018. Crowding was measured using the ED occupancy rate. Any cases assigned to a higher level on initial rather than the final evaluation were defined as overtriage, while any cases assigned to a lower level on initial rather than the final evaluation were defined as under-triage. Results: The ED occupancy rate, which represents the level of ED overcrowding, scored 1.24±0.45 in case of undertriage, and 1.36±0.51 in case of over-triage. KTAS re-evaluation did not vary significantly based on the ED occupancy rate. The treatment results were analyzed according to the different KTAS grades of the KTAS re-evaluation group. The treatment results were different depending on the degree of under-triage. In the under-triage group, patients with a KTAS 2 or 3-grade difference had higher rates of ED hospitalization, mortality, and inter-hospital transfer than the patients with a KTAS 1 grade difference, and this variation was significant. Conclusion KTAS re-evaluation was not related to overcrowding in the ED. Among the KTAS re-evaluation cases, under-triage patients had higher rates of ED hospitalization, mortality, and hospital transfer. The triage provider, therefore, needs to be more careful at the time of initial classification.

Objective: The purpose of the study was to analyze triage re-evaluation characteristics of the Korean Triage and Acuity Scale (KTAS). In particular, the relationship between overcrowding and KTAS re-evaluation at the emergency department (ED) was analyzed. Methods: In this study, a retrospective chart review of 3,158 KTAS re-evaluation cases was performed. The sample included patients visiting a regional ED from January 1 to December 31 in 2018. Crowding was measured using the ED occupancy rate. Any cases assigned to a higher level on initial rather than the final evaluation were defined as overtriage, while any cases assigned to a lower level on initial rather than the final evaluation were defined as under-triage. Results: The ED occupancy rate, which represents the level of ED overcrowding, scored 1.24±0.45 in case of undertriage, and 1.36±0.51 in case of over-triage. KTAS re-evaluation did not vary significantly based on the ED occupancy rate. The treatment results were analyzed according to the different KTAS grades of the KTAS re-evaluation group. The treatment results were different depending on the degree of under-triage. In the under-triage group, patients with a KTAS 2 or 3-grade difference had higher rates of ED hospitalization, mortality, and inter-hospital transfer than the patients with a KTAS 1 grade difference, and this variation was significant. Conclusion KTAS re-evaluation was not related to overcrowding in the ED. Among the KTAS re-evaluation cases, under-triage patients had higher rates of ED hospitalization, mortality, and hospital transfer. The triage provider, therefore, needs to be more careful at the time of initial classification.

Recent advances in computer technology have generated a new area of research known as radiomics. Radiomics is defined as the high throughput extraction and analysis of quantitative features from imaging data. Radiomic features provide information on the gray-scale patterns, inter-pixel relationships, as well as shape and spectral properties of radiological images. Moreover, these features can be used to develop computational models that may serve as a tool for personalized diagnosis and treatment guidance. Although radiomics is becoming popular and widely used in oncology, many problems such as overfitting and reproducibility issues remain unresolved. In this review, we will outline the steps of radiomics used for oncology, specifically addressing applications for breast cancer patients and focusing on technical issues.

Background: This study aimed to improve the clinical course of patients through rapid response by analyzing the characteristics of critically ill patients with confirmed coronavirus disease 2019 (COVID-19) in Busan between December 1, 2020, and December 31, 2021. Methods: We divided patients diagnosed with COVID-19 into mild-to-moderate and critical groups based on their clinical severity. The critically ill patients were further sub-divided into delta and delta variant non-epidemic group. Results: The following factors were significantly more frequent in critically ill patients than in patients with mild-tomoderate symptoms: male sex, age ≥60 years, symptoms at the time of diagnosis, and those with underlying diseases. The following factors were significantly more common in the non-delta variant epidemic group than in the delta variant epidemic group in critically ill patients: male sex, age ≥60 years, underlying diseases, and not being vaccinated. In the delta variant epidemic group, the duration between confirmation of disease and its progression to critically ill status was significantly shorter than that in the non-delta variant epidemic group. Conclusion COVID-19 is characterized by the emergence of new variants and repeated epidemics. Therefore, it is necessary to analyze the characteristics of critically ill patients to efficiently distribute and manage medical resources.

Strengthening primary care has always been a major policy issue in most developed countries to achieve the health care system's goals, and policy makers continuously try to use payment system as an effective tool to improve overall performance of primary care. In this paper, we examined the various payment methods and growing trends in primary care payment system in some developed countries. Overall, a common form of payment for primary care doctors is a blend of fee-for-service (FFS), capitation, and pay-for-performance (P4P). In addition, many countries are still in the way of many new trials to find the right way to provide primary care service effectively, to meet the complex health care needs of populations. In Korea, primary care system is not well-established, and other institutional arrangements are not in good conditions for primary care, either. FFS, which is a dominant payment method in Korea, is not favorable for achieving good attributes of primary care. Mixing various payment components, like capitation, P4P to current FFS is essential to provide the optimal incentive structures for primary care physicians. Also, new models to encourage doctor-patient relationships with appropriate P4P mechanisms could be used as an early step in reforming primary care payment system gradually.
Administrative Personnel ; Delivery of Health Care ; Developed Countries ; Fee-for-Service Plans ; Humans ; Korea ; Motivation ; Physicians, Primary Care ; Primary Health Care ; Reimbursement, Incentive

In Korea, demand for autologous serum eye drops (ASEs) is increasing for treatment of severe dry eye diseases. However, since the MFDS (Ministry of Food and Drug Safety) does not have guidelines for use of ASEs, they are manufactured according to their own protocols by each medical institution. ASEs should be taken with caution to avoid contamination during the manufacturing process since blood must be used as a raw material and must be prepared in an open space. In this paper, we briefly review reports on ASEs and share our experience with the introduction of ASE manufacturing protocols at Severance hospital.
Eye Diseases ; Korea ; Ophthalmic Solutions*

The aim of this study is to investigate visual exploration of children and adolescents during dental treatment by examining time ratio of eye opening in various age groups.
This study reviewed 5 - 15 year-old patients who visited the department of pediatric dentistry of Yonsei University Dental Hospital from March to October 2018. Restorative treatment or sealant application was done by one pediatric dentist. A trained observer used 2 stopwatches to measure total treatment time and time of open eye. Average ratios of eye opening were calculated and compared.
60 patients were investigated, with 15 patients in each age group. Average ratio of eye opening increased as age decreased (p < .001). The average of 13 - 15 year-olds was significantly shorter than that of children younger than 12 years (p < .005).
This study indicated that children have higher rates of eye opening during dental treatment than adolescents.

Hypercalcemia is a common complication in CAPD patients treated with calcium-containing phosphate binders and using the standard dialysate (SCD) calcium concentration of 3.5mEq/L. We performed a retrospective study in 25 CAPD patients to determine whether a low calcium dialysate (LCD) containing 2.5mEq/L calcium would reduce the incidence of hypercalemia with adequate control of serum inorganic phosphate levels and diminish the need to use aluminum-containing phosphate binders. All patients had previously used SCD before converting to LCD. The incidence of hypercalcemia (more than 2 episodes of corrected serum calcium > or = 10.5mg/dL) tended to be lower after converting to LCDl 0.27 (0-2.76) vs. 0 (0-1.97) episodes/patient-yearl. Intact PTH level increased from 38.8 (0.1-1599.3)pg/mL to 70.6 (9.5-1540.0)pg/mL after conversion, but there was no statistical sifnificance. Serum calcium, inorganic phosphate, alkaline phosphatase and bicarbonate levels did not change after converting to LCD. We were able to reduce aluminum hydroxide dosagel 1.09 (0-10.88) vs. 0 (0-3.26)g/day/patientl and increase calcium carbonate dosage (1.95 0.92 vs. 2.98 2.14g/day/ patient) after conversion significantly (P<0.05). The frequency of peritonitis was similar in LCD and SCD period. In conclusion, low calcium dialysate is useful in diminishing aluminum-containing phosphate binder dosage and increasing calcium carbonate dosage to maintain a similar phosphate value. Its effects on renal osteodystrophy remain to be assessed.
Alkaline Phosphatase ; Aluminum Hydroxide ; Calcium Carbonate ; Calcium* ; Humans ; Hypercalcemia ; Incidence ; Kidney Failure, Chronic ; Peritoneal Dialysis, Continuous Ambulatory* ; Peritonitis ; Renal Osteodystrophy ; Retrospective Studies

Black staining of the teeth in children and adolescents does not cause pain or serious illness, but it can be socially debilitating for esthetic reasons. Black staining is easily removed through periodic professional mechanical tooth cleaning and ultrasonic scaling, but it can easily recur within few months. Using essential oil-containing mouth rinses diluted at 50% twice per day could prevent the black staining from returning after it is removed, reducing the need for mechanical treatments and improving esthetics.