Comparison between Statistical Models and Machine Learning Methods on Classification for Highly Imbalanced Multiclass Kidney Data.

This study aims to compare the classification performance of statistical models on highly imbalanced kidney data. The health examination cohort database provided by the National Health Insurance Service in Korea is utilized to build models with various machine learning methods. The glomerular filtration rate (GFR) is used to diagnose chronic kidney disease (CKD). It is calculated using the Modification of Diet in Renal Disease method and classified into five stages (1, 2, 3A and 3B, 4, and 5). Different CKD stages based on the estimated GFR are considered as six classes of the response variable. This study utilizes two representative generalized linear models for classification, namely, multinomial logistic regression (multinomial LR) and ordinal logistic regression (ordinal LR), as well as two machine learning models, namely, random forest (RF) and autoencoder (AE). The classification performance of the four models is compared in terms of accuracy, sensitivity, specificity, precision, and F1-Measure. To find the best model that classifies CKD stages correctly, the data are divided into a 10-fold dataset with the same rate for each CKD stage. Results indicate that RF and AE show better performance in accuracy than the multinomial and ordinal LR models when classifying the response variable. However, when a highly imbalanced dataset is modeled, the accuracy of the model performance can distort the actual performance. This occurs because accuracy is high even if a statistical model classifies a minority class into a majority class. To solve this problem in performance interpretation, we not only consider accuracy from the confusion matrix but also sensitivity, specificity, precision, and F-1 measure for each class. To present classification performance with a single value for each model, we calculate the macro-average and micro-weighted values for each model. We conclude that AE is the best model classifying CKD stages correctly for all performance indices.

The association of low muscle mass with soluble receptor for advanced glycation end products (sRAGE): The Korean Sarcopenic Obesity Study (KSOS).

BACKGROUND: Advanced glycation end products (AGEs) are accumulated with aging in various tissues of humans. The soluble receptor for AGEs (sRAGE) exerts a protective role against the development of aging-related chronic disorders by neutralizing the action of AGEs. We investigated the implication of sRAGE on low muscle mass in Asian men and women. METHODS: This cross-sectional study included a 390-participant, nondiabetic subcohort recruited within the framework of the Korean Sarcopenic Obesity Study, an ongoing prospective cohort study. Low muscle mass was defined based on the distribution of appendicular skeletal muscle mass divided by body mass index, as proposed by the Foundation for the National Institutes Sarcopenia Project. RESULTS: Serum sRAGE levels were significantly lower in participants with low muscle mass than in participants without low muscle mass (0.76 [0.60-1.00] ng/mL vs 0.87 [0.67-1.15] ng/mL, P = .005). In age- and sex-adjusted correlation analyses, appendicular skeletal muscle mass divided by body mass index was associated with sRAGE (r = 0.109, P = .037). Furthermore, decreased circulating levels of sRAGE are independently associated with low muscle mass (odds ratio = 0.254, P = .002) after adjusting for confounding factors, including insulin resistance and inflammatory markers. CONCLUSIONS: The present study shows that a low circulating level of sRAGE may be an independent risk factor for the presence of low muscle mass.

Comparisons of three different methods for defining sarcopenia: An aspect of cardiometabolic risk.

Appraisal of muscle mass is important when considering the serious consequences of sarcopenia in an aging society. However, the associations between sarcopenia and its clinical outcomes might vary according to the method applied in its diagnosis. We compared the relationships between cardiometabolic risk parameters and sarcopenia defined according to three different diagnostic methods using dual-energy X-ray absorptiometry (DXA) and computed tomography (CT). Appendicular skeletal muscle mass (ASM) adjusted by height squared and BMI (ASM/height2 and ASM/BMI) measured using DXA and thigh muscle cross-sectional area (tmCSA) adjusted by weight (tmCSA/weight) measured using CT were used as indices of muscle mass. Sarcopenia was defined as two standard deviations below either the mean ASM/height2, ASM/BMI, or tmCSA/weight of a young reference group. ASM/BMI and tmCSA/weight showed a negative relationship with several components of metabolic syndrome and HOMA-IR, whereas ASM/height2 was positively associated with theses cardiometabolic risk factors. Logistic regression analyses demonstrated that ASM/BMI-defined sarcopenia was significantly associated with increased HOMA-IR (P = 0.01) and prevalence of visceral obesity (P = 0.03) and metabolic syndrome (P = 0.025), while ASM/height2- and tmCSA/weight-defined sarcopenia were not. ASM/BMI-defined sarcopenia exhibits a closer relationship with cardiometabolic risk factors than does ASM/height2- or tmCSA/weight-defined sarcopenia.

Development and External Validation of the Korean Prostate Cancer Risk Calculator for High-Grade Prostate Cancer: Comparison with Two Western Risk Calculators in an Asian Cohort.

PURPOSE: We developed the Korean Prostate Cancer Risk Calculator for High-Grade Prostate Cancer (KPCRC-HG) that predicts the probability of prostate cancer (PC) of Gleason score 7 or higher at the initial prostate biopsy in a Korean cohort (http://acl.snu.ac.kr/PCRC/RISC/). In addition, KPCRC-HG was validated and compared with internet-based Western risk calculators in a validation cohort. MATERIALS AND METHODS: Using a logistic regression model, KPCRC-HG was developed based on the data from 602 previously unscreened Korean men who underwent initial prostate biopsies. Using 2,313 cases in a validation cohort, KPCRC-HG was compared with the European Randomized Study of Screening for PC Risk Calculator for high-grade cancer (ERSPCRC-HG) and the Prostate Cancer Prevention Trial Risk Calculator 2.0 for high-grade cancer (PCPTRC-HG). The predictive accuracy was assessed using the area under the receiver operating characteristic curve (AUC) and calibration plots. RESULTS: PC was detected in 172 (28.6%) men, 120 (19.9%) of whom had PC of Gleason score 7 or higher. Independent predictors included prostate-specific antigen levels, digital rectal examination findings, transrectal ultrasound findings, and prostate volume. The AUC of the KPCRC-HG (0.84) was higher than that of the PCPTRC-HG (0.79, p<0.001) but not different from that of the ERSPCRC-HG (0.83) on external validation. Calibration plots also revealed better performance of KPCRC-HG and ERSPCRC-HG than that of PCPTRC-HG on external validation. At a cut-off of 5% for KPCRC-HG, 253 of the 2,313 men (11%) would not have been biopsied, and 14 of the 614 PC cases with Gleason score 7 or higher (2%) would not have been diagnosed. CONCLUSIONS: KPCRC-HG is the first web-based high-grade prostate cancer prediction model in Korea. It had higher predictive accuracy than PCPTRC-HG in a Korean population and showed similar performance with ERSPCRC-HG in a Korean population. This prediction model could help avoid unnecessary biopsy and reduce overdiagnosis and overtreatment in clinical settings.

High Incidence of Breast Cancer in Light-Polluted Areas with Spatial Effects in Korea.

We have reported a high prevalence of breast cancer in light-polluted areas in Korea. However, it is necessary to analyze the spatial effects of light polluted areas on breast cancer because light pollution levels are correlated with region proximity to central urbanized areas in studied cities. In this study, we applied a spatial regression method (an intrinsic conditional autoregressive [iCAR] model) to analyze the relationship between the incidence of breast cancer and artificial light at night (ALAN) levels in 25 regions including central city, urbanized, and rural areas. By Poisson regression analysis, there was a significant correlation between ALAN, alcohol consumption rates, and the incidence of breast cancer. We also found significant spatial effects between ALAN and the incidence of breast cancer, with an increase in the deviance information criterion (DIC) from 374.3 to 348.6 and an increase in R2 from 0.574 to 0.667. Therefore, spatial analysis (an iCAR model) is more appropriate for assessing ALAN effects on breast cancer. To our knowledge, this study is the first to show spatial effects of light pollution on breast cancer, despite the limitations of an ecological study. We suggest that a decrease in ALAN could reduce breast cancer more than expected because of spatial effects.

Vulnerabilities to Temperature Effects on Acute Myocardial Infarction Hospital Admissions in South Korea.

Most previous studies have focused on the association between acute myocardial function (AMI) and temperature by gender and age. Recently, however, concern has also arisen about those most susceptible to the effects of temperature according to socioeconomic status (SES). The objective of this study was to determine the effect of heat and cold on hospital admissions for AMI by subpopulations (gender, age, living area, and individual SES) in South Korea. The Korea National Health Insurance (KNHI) database was used to examine the effect of heat and cold on hospital admissions for AMI during 2004-2012. We analyzed the increase in AMI hospital admissions both above and below a threshold temperature using Poisson generalized additive models (GAMs) for hot, cold, and warm weather. The Medicaid group, the lowest SES group, had a significantly higher RR of 1.37 (95% CI: 1.07-1.76) for heat and 1.11 (95% CI: 1.04-1.20) for cold among subgroups, while also showing distinctly higher risk curves than NHI for both hot and cold weather. In additions, females, older age group, and those living in urban areas had higher risks from hot and cold temperatures than males, younger age group, and those living in rural areas.

High prevalence of breast cancer in light polluted areas in urban and rural regions of South Korea: An ecologic study on the treatment prevalence of female cancers based on National Health Insurance data.

It has been reported that excessive artificial light at night (ALAN) could harm human health since it disturbs the natural bio-rhythm and sleep. Such conditions can lead to various diseases, including cancer. In this study, we have evaluated the association between ALAN and prevalence rates of cancer in females on a regional basis, after adjusting for other risk factors, including obesity, smoking, alcohol consumption rates and PM10 levels. The prevalence rates for breast cancer were found to be significantly associated with ALAN in urban and rural areas. Furthermore, no association was found with ALAN in female lung, liver, cervical, gastric and colon cancer. Despite the limitations of performing ecological studies, this report suggests that ALAN might be a risk factor for breast cancer, even in rural areas.

Lessons learned from a comparative analysis of surgical outcomes of and learning curves for laparoscopy-assisted distal gastrectomy.

PURPOSE: Before expanding our indications for laparoscopic gastrectomy to advanced gastric cancer and adopting reduced port laparoscopic gastrectomy, we analyzed and audited the outcomes of laparoscopy-assisted distal gastrectomy (LADG) for adenocarcinoma; this was done during the adoptive period at our institution through the comparative analysis of short-term surgical outcomes and learning curves (LCs) of two surgeons with different careers. MATERIALS AND METHODS: A detailed comparative analysis of the LCs and surgical outcomes was done for the respective first 95 and 111 LADGs performed by two surgeons between July, 2006 and June, 2011. The LCs were fitted by using the non-linear ordinary least squares estimation method. RESULTS: The postoperative morbidity and mortality rates were 14.6% and 0.0%, respectively, and there was no significant difference in the morbidity rates (12.6% vs. 16.2%, P=0.467). More than 25 lymph nodes were retrieved by each surgeon during LADG procedures. The LCs of both surgeons were distinct. In this study, a stable plateau of the LC was not achieved by both surgeons even after performing 90 LADGs. CONCLUSIONS: Regardless of the experience with gastrectomy or laparoscopic surgery for other organs, or the age of surgeon, the outcome was quite acceptable; the learning process differ according to the surgeon's experience and individual characteristics.

Impact of visceral fat on skeletal muscle mass and vice versa in a prospective cohort study: the Korean Sarcopenic Obesity Study (KSOS).

OBJECTIVES: Sarcopenia and visceral obesity have been suggested to aggravate each other, resulting in a vicious cycle. However, evidence based on prospective study is very limited. Our purpose was to investigate whether visceral fat promotes a decrease in skeletal muscle mass and vice versa. METHODS: We observed changes in anthropometric and body composition data during a follow-up period of 27.6 ± 2.8 months in 379 Korean men and women (mean age 51.9 ± 14.6 years) from the Korean Sarcopenic Obesity Study (KSOS). Appendicular lean soft tissue (ALST) mass was calculated using dual-energy X-ray absorptiometry, and visceral fat area (VFA) was measured using computed tomography at baseline and follow-up examination. RESULTS: ALST mass significantly decreased, whereas trunk and total fat mass increased in both men and women despite no significant change in weight and body mass index. In particular, women with visceral obesity at baseline had a greater decrease in ALST mass than those without visceral obesity (P = 0.001). In multiple linear regression analysis, baseline VFA was an independent negative predictor of the changes in ALST after adjusting for confounding factors including age, gender, life style and body composition parameters, insulin resistance, high sensitivity C-reactive protein and vitamin D levels (P = 0.001), whereas the association between baseline ALST mass and changes in VFA was not statistically significant (P = 0.555). CONCLUSIONS: This longitudinal study showed that visceral obesity was associated with future loss of skeletal muscle mass in Korean adults. These results may provide novel insight into sarcopenic obesity in an aging society.

Association of low muscle mass and combined low muscle mass and visceral obesity with low cardiorespiratory fitness.

OBJECTIVE: Previous studies have shown that low cardiorespiratory fitness (CRF), visceral obesity and low muscle mass may share pathophysiological mechanisms, such as insulin resistance and chronic inflammation. In this study, we investigated whether low CRF is associated with low muscle mass, visceral obesity, and visceral obesity combined with low muscle mass. RESEARCH DESIGN AND METHODS: The associations between CRF and low muscle mass and combined low muscle mass and visceral obesity were examined in 298 apparently healthy adults aged 20-70 years. Low muscle mass was defined using a skeletal muscle mass index (SMI) that was calculated using dual energy X-ray absorptiometry. Visceral obesity was defined as a visceral fat area (VFA) exceeding 100 cm2 in women and 130 cm2 in men. We classified the participants into 4 low muscle mass/visceral obesity groups according to SMI and VFA. CRF was measured using a cycle ergometer test. RESULTS: CRF level correlated positively with SMI and negatively with VFA. Individuals with low muscle mass had lower CRF values than those without low muscle mass. After adjustment for age, sex, lifestyle factors, and markers for insulin resistance and inflammation, participants in the lowest quartile of CRF had an odds ratio (OR) for low muscle mass of 4.98 compared with those in the highest quartile (95% confidence interval (CI) = 1.19-12.99; P for trend = 0.001) and an OR for combined low muscle mass and visceral obesity of 31.46 (95% CI = 4.31-229.68; P for trend = 0.001). CONCLUSIONS: Individuals with lower CRF exhibited increased risk of low muscle mass and combined low muscle mass and visceral obesity. These results suggest that low CRF may be a potential indicator for low muscle mass and combined low muscle mass and visceral obesity in Korean adults.

Short-term effect of temperature on daily emergency visits for acute myocardial infarction with threshold temperatures.

BACKGROUND: The relationship between temperature and myocardial infarction has not been fully explained. In this study, we identified the threshold temperature and examined the relationship between temperature and emergency admissions due to MI in Korea. METHODS: Poisson generalized additive model analyses were used to assess the short-term effects of temperature (mean, maximum, minimum, diurnal) on MI emergency visits, after controlling for meteorological variable and air pollution (PM10, NO2). We defined the threshold temperature when the inflection point showed a statistically significant difference in the regression coefficients of the generalized additive models (GAMs) analysis. The analysis was performed on the following subgroups: geographical region, gender, age (<75 years or ≥ 75 years), and MI status (STEMI or non-STEMI). RESULTS: The threshold temperatures during heat exposure were for the maximum temperature as 25.5-31.5°C and for the mean temperature as 27.5-28.5°C. The threshold temperatures during cold exposure were for the minimum temperature as -2.5-1.5°C. Relative risks (RRs) of emergency visits above hot temperature thresholds ranged from 1.02 to 1.30 and those below cold temperature thresholds ranged from 1.01 to 1.05. We also observed increased RRs ranged from 1.02 to 1.65 of emergency visits when temperatures changes on a single day or on successive days. CONCLUSIONS: We found a relationship between temperature and MI occurrence during both heat and cold exposure at the threshold temperature. Diurnal temperature or temperature change on successive days also increased MI risk.

The association of Klotho gene polymorphism with the mortality of patients on maintenance dialysis.

Despite medical progress, high morbidity and mortality rates have persisted in patients with end-stage renal disease (ESRD). The role in atherosclerosis and cardiovascular disease of klotho, an aging process-related gene, has been highlighted. Genetic variation in klotho has been reported to be a risk factor for coronary artery disease and ischemic stroke. Regarding the significance of cardiovascular disease for the outcome of ESRD patients, we investigated whether genetic variation of klotho was associated with mortality in ESRD patients on hemodialysis. 478 patients on maintenance hemodialysis for more than 3 months at dialysis facilities affiliated with the Western Dialysis Physician Association were enrolled in September 2004. Patient survival was checked annually until September 2007. Genotypings of klotho in terms of G395A in the promoter region, C1818T in exon 4, and KL-VS was performed. 45 deaths (11.2%) occurred over 3 years. Mortality was higher in the GA+AA group than in the GG group (18.9% vs. 6.7%, respectively, p < 0.001). Kaplan-Meier analysis also revealed that the survival of the GA+AA group was worse than that of GG group (p = 0.002). Cox's proportional hazards regression analysis showed that age, A allele carrier status in G395A of klotho, hemoglobin, albumin and HDL cholesterol levels were the significant factors affecting survival of hemodialysis patients. The A allele of the G395A polymorphism of klotho may be associated with the risk of mortality in Korean hemodialysis patients. Age, hemoglobin, albumin and HDLC were also significant prognostic factors for survival in the present study.

Serum adipocyte fatty acid-binding protein levels are independently associated with sarcopenic obesity.

AIMS: Adipocyte fatty acid-binding protein (A-FABP) plays a key role in obesity-related insulin resistance and inflammation which may be involved in the pathogenesis of sarcopenic obesity (SO). This study examined the association of SO with serum A-FABP levels in Korean adults. METHODS: Two hundred ninety eight adults aged 20-70 years were examined using dual X-ray absorptiometry and computed tomography and measuring serum A-FABP levels. Sarcopenia was defined as the appendicular skeletal muscle mass (ASM) divided by weight (%) of <1 SD below the mean values of young adults in both sexes. Obesity was defined as visceral fat area (VFA) ≥ 100 cm(2). RESULTS: Serum A-FABP levels were higher in groups with SO compared to non-SO groups in both men and women. In the unadjusted model, serum A-FABP levels were positively associated with VFA and negatively associated with ASM/weight. Even after adjusting for possible confounding factors, ASM/weight was found to be independently and negatively associated with serum A-FABP levels. In addition, multiple logistic regression analysis showed that increased serum levels of A-FABP were independently associated with the presence of SO. CONCLUSIONS: The present findings indicate that serum A-FABP levels may be valuable markers of the presence of SO.

Medial arch orthosis for paediatric flatfoot.

PURPOSE: To evaluate any correlation between various foot angles and their respective American Orthopaedic Foot and Ankle Society (AOFAS) scores for pain, and the effectiveness of a medial arch orthosis. METHODS: 81 children with bilateral symptomatic flatfoot were randomised into orthosis (n=55) and control (n=26) groups. The orthosis group consisted of 33 male and 22 female patients aged 36 to 204 (mean, 99) months and they were given a medial arch support. The control group consisted of 15 male and 11 female patients aged 36 to 192 (mean, 100) months and they were managed with analgesics. Foot angles including anteroposterior (AP) and lateral talocalcaneal (TC) angles, AP and lateral talo- first metatarsal (TFM) angles, calcaneal pitch angle (in lateral plane), and talonavicular (TN) angle were measured, as were AOFAS scores for pain for the forefoot, midfoot, and hindfoot. RESULTS: After orthosis treatment, all AOFAS scores and all foot angles (except for the AP-TN angle) improved significantly. In the controls, all AOFAS scores (except for the midfoot score) and only the AP-TFM angle improved significantly. In the orthosis group, the AOFAS hindfoot score correlated positively with the lateral TC angle of the left foot (r=0.345, p=0.010) and negatively with the calcaneal pitch angle of the right foot (r=-0.33, p=0.015). In the control group, the lateral TFM angle of the left foot correlated negatively with the AOFAS forefoot (r=-0.566, p=0.003) and midfoot scores (r=-0.497, p=0.001), whereas the calcaneal pitch angle of the left foot correlated positively with the AOFAS forefoot score (r=0.497, p=0.010). CONCLUSION: Medial arch support orthosis significantly improved AOFAS scores and foot angles. Calcaneal pitch angle and lateral TC angle correlated well with AOFAS hindfoot scores.

Body size phenotypes and low muscle mass: the Korean sarcopenic obesity study (KSOS).

CONTEXT: Unique subsets of body size phenotypes seem to be more prone or more resistant to the development of obesity-associated metabolic disorders, although the underlying mechanism is not yet clearly understood. OBJECTIVES: We investigated the prevalence and risk of low muscle mass in subjects who are classified as either metabolically healthy normal weight (MHNW), metabolically abnormal but normal weight (MANW), metabolically healthy obese (MHO), or metabolically abnormal obese (MAO). Subjects were classified based on body mass index and presence of metabolic syndrome. METHODS: Thigh muscle cross-sectional area was evaluated using computed tomography as an index of muscle mass in 492 apparently healthy adults enrolled in the Korean Sarcopenic Obesity Study (KSOS), an ongoing prospective observational cohort study. Low muscle mass was defined as thigh muscle cross-sectional area divided by weight (percent) of <1 SD below the mean values of young adults in both sexes. RESULTS: The prevalence rates of low muscle mass in MHNW, MANW, MHO, and MAO subjects were 6.2%, 17.8%, 23.2%, and 33.7%, respectively. In a multiple logistic regression analysis, men with the MANW phenotype showed a remarkably increased risk of low muscle mass (odds ratio = 11.30, 95% confidence interval, 1.73-73.28) compared with those with MHNW. Furthermore, in both men and women, MHO or MAO subjects had higher odds ratios of low muscle mass compared with MHNW subjects. CONCLUSIONS: The present study suggests that low muscle mass may be associated with different metabolic consequences according to body size phenotype.

Relationships between sarcopenic obesity and insulin resistance, inflammation, and vitamin D status: the Korean Sarcopenic Obesity Study.

OBJECTIVE: It has been suggested that insulin resistance, low-grade inflammation and vitamin D deficiency are associated with obesity and sarcopenia. However, their relationships with sarcopenic obesity (SO) are unclear. We evaluated the impact of homoeostasis model assessment of insulin resistance (HOMA-IR), high-sensitivity C-reactive protein (hsCRP) and 25-hydroxyvitamin D (25[OH]D) levels on SO in Korean adults. STUDY SUBJECT/MEASUREMENTS: This study included 493 apparently healthy adults (180 men and 313 women) enrolled in the Korean Sarcopenic Obesity Study. Sarcopenia was defined as a skeletal muscle mass index (SMI) of 1 SD below the sex-specific mean value for a young reference group. Obesity was defined as a visceral fat area (VFA) ≥100 cm(2) . We classified the participants into four sarcopenia/obesity groups based on both SMI and VFA. RESULTS: The prevalence of SO was 17·8% in men and 24·9% in women. In women, the SO group had higher HOMA-IR and hsCRP levels compared with the non-SO group. In men, the 25[OH]D levels were significantly lower in the SO group than the non-SO group. Both hsCRP and HOMA-IR levels were negatively correlated with SMI and positively correlated with VFA in both men and women, whereas 25[OH]D levels were positively correlated with SMI in both men and women. Multiple binary logistic regression analysis showed that HOMA-IR and 25[OH]D levels were independently associated with SO in men, while HOMA-IR and hsCRP were significant factors predicting SO in women. CONCLUSION: Insulin resistance, inflammation and vitamin D deficiency were associated with SO in a Korean adult population.

A comparative pilot study of symptom improvement before and after phototherapy in Korean patients with perennial allergic rhinitis.

Although allergic rhinitis is not life threatening, it significantly influences the quality of a patient's life. This study is intended to evaluate the safety and efficacy of phototherapy with low-level energy of a 650 nm laser irradiation system in perennial allergic rhinitis patients. This clinical trial was an open-label, single-center study with 42 perennial allergic rhinitis subjects. Following laser irradiation in the nasal cavity with a laser irradiation system, the efficacy at weeks 1 through 4 was determined. The symptoms were scored with four parameters (nasal obstruction, rhinorrhea, sneezing and itching) before and after illumination of the laser, and the total score was recorded. A survey of Rhinoconjunctivitis Quality of Life Questionnaire (RQLQ) was conducted by patients before and after treatment. Following treatment, significant improvement in the clinical symptoms of nasal obstruction (P < 0.001), rhinorrhea (P = 0.005), sneezing (P = 0.001) and itching (P = 0.003) was reported by 68% of perennial allergic rhinitis patients. The overall RQLQ scores significantly improved by 45% from the baseline with the treatment after 4 weeks. These results indicate that phototherapy is an effective modality for treating perennial allergic rhinitis and is another option in the steroid-free management of immune-mediated mucosal diseases.

Elevated A1C is associated with impaired early-phase insulin secretion rather than insulin resistance in Koreans at high risk for developing diabetes.

The purpose of this study is to examine the association of A1C with beta-cell dysfunction, insulin resistance, and cardiovascular risk factors in Koreans with the relatively high risk for the future development of diabetes. This cross-sectional study recruited subjects from the pre-diabetic cohort of the Korea National Diabetes Program. Among study subjects (n = 616) aged 21-77 years with a history of hyperglycemia (fasting plasma glucose (FPG) ≥ 5.5 mmol/mL), analyses were conducted on 504 participants (296 women, 208 men) except for subjects with FPG ≥ 7.0 mmol/L or 120-min post-challenge plasma glucose ≥ 11.1 mmol/L or A1C ≥ 6.5 %. For insulin sensitivity and ß-cell function classified by the categories of A1C levels, ∆Ins(30-0)/∆Glu(30-0) was lower in the highest quartile group than other groups. Although there was no significant difference in HOMA-IR according to the A1C categories, even lowest A1C group (≤ 5.3 %) already included many subjects with abnormal glucose tolerance. A1C showed a significant association with hsCRP, number of metabolic syndrome (MetS) components and ∆Ins(30-0)/∆Glu(30-0) after adjusting for age, gender, BMI, and medications whereas HOMA-IR was insignificantly associated with A1C. Stepwise regression analysis for A1C showed that A1C is independently and negatively associated with ∆Ins(30-0)/∆Glu(30-0), and positively associated with hsCRP. Our study showed that higher A1C was associated with impaired early-phase insulin secretion, MetS, and low grade inflammation in Koreans with the relatively high risk for the future development of diabetes.

The differential relationship between fat mass and bone mineral density by gender and menopausal status.

Osteoporosis and obesity are important public health problems in an aging society. We investigated the differential impacts of fat on bone mineral density (BMD) according to gender and menopausal status. We analyzed the baseline data of an ongoing observational cohort study, including a total of 502 healthy subjects 20-88 years of age (144 men, 159 premenopausal women, 199 postmenopausal women). Body composition and fat mass were measured using computed tomography and dual energy X-ray absorptiometry (DXA). BMD was measured at lumbar spines using DXA. In men and postmenopausal women, there was no significant correlation between fat and bone parameters after adjusting for age and body weight. However, in premenopausal women, BMD had significant negative correlations with waist circumference, total fat area, subcutaneous fat area, appendicular fat mass and percentage fat mass after adjusting for age and body weight. Furthermore, only in premenopausal women, the subjects with the highest quartile of percentage fat mass had the lowest BMD even after adjusting for confounding factors including age, body weight, physical activity, alcohol use and smoking history. Multiple linear regression analysis showed that percentage fat mass was a significant negative decisive factor for BMD in premenopausal women. Our study showed the differential relationship between fat mass and BMD according to gender and menopausal status. Only in premenopausal women did fat mass have a significant negative effect on bone mass. This result suggests the importance of reducing fat mass in order to achieve peak bone mass in young adult women.

Rapid adaptation of robotic gastrectomy for gastric cancer by experienced laparoscopic surgeons.

BACKGROUND: Robotic surgery for gastric cancer patients has been increasing because of its many advantages over conventional laparoscopic surgery. Despite the suggestion that robotic surgery may lessen the learning curve for complex laparoscopic procedures, little is known about the learning curve for robotic gastrectomy. This study aimed to assess the learning curve of robotic gastrectomy for patients with cancer by analyzing the operation time. METHODS: The first 20 consecutive cases of robot-assisted distal gastrectomy with lymphadenectomy for gastric cancer performed by three experienced laparoscopic surgeons' using the da Vinci system were collected and reviewed. A nonlinear least-squares method was developed and used to analyze the learning curves. RESULTS: Overall, the mean operation time was 247.3 ± 45.7 min, depending on each surgeon's laparoscopic experience and the patient's characteristics. After control was used for confounding factors, the stabilized operation time decreased to 211.8 min. The operation time stabilized at 8.2 cases and was reduced 111.4 min from the first case. A stable operation time was reached in 9.6 cases by surgeon A, in 18.1 cases by surgeon B, and in 6 cases by surgeon C. The stable operation time was 149.2 min for surgeon A, 127.1 min for surgeon B, and 236.8 min for surgeon C, and the reduction in operation time from the first case to stabilization was 233 min for surgeon A, 76.7 min for surgeon B, and 154.6 min for surgeon C. CONCLUSIONS: Surgeons with sufficient experience in laparoscopic gastrectomy can rapidly overcome the learning curve for robotic gastrectomy. In addition, the surgeon's experience with laparoscopic gastrectomy affects the operation time after stabilization and the reduction in operation time.