Effectiveness of data-augmentation on deep learning in evaluating rapid on-site cytopathology at endoscopic ultrasound-guided fine needle aspiration.

Rapid on-site cytopathology evaluation (ROSE) has been considered an effective method to increase the diagnostic ability of endoscopic ultrasound-guided fine needle aspiration (EUS-FNA); however, ROSE is unavailable in most institutes worldwide due to the shortage of cytopathologists. To overcome this situation, we created an artificial intelligence (AI)-based system (the ROSE-AI system), which was trained with the augmented data to evaluate the slide images acquired by EUS-FNA. This study aimed to clarify the effects of such data-augmentation on establishing an effective ROSE-AI system by comparing the efficacy of various data-augmentation techniques. The ROSE-AI system was trained with increased data obtained by the various data-augmentation techniques, including geometric transformation, color space transformation, and kernel filtering. By performing five-fold cross-validation, we compared the efficacy of each data-augmentation technique on the increasing diagnostic abilities of the ROSE-AI system. We collected 4059 divided EUS-FNA slide images from 36 patients with pancreatic cancer and nine patients with non-pancreatic cancer. The diagnostic ability of the ROSE-AI system without data augmentation had a sensitivity, specificity, and accuracy of 87.5%, 79.7%, and 83.7%, respectively. While, some data-augmentation techniques decreased diagnostic ability, the ROSE-AI system trained only with the augmented data using the geometric transformation technique had the highest diagnostic accuracy (88.2%). We successfully developed a prototype ROSE-AI system with high diagnostic ability. Each data-augmentation technique may have various compatibilities with AI-mediated diagnostics, and the geometric transformation was the most effective for the ROSE-AI system.

WONDER-02: plastic stent vs. lumen-apposing metal stent for endoscopic ultrasound-guided drainage of pancreatic pseudocysts-study protocol for a multicentre randomised non-inferiority trial.

BACKGROUND: Endoscopic ultrasound (EUS)-guided transluminal drainage has become a first-line treatment modality for symptomatic pancreatic pseudocysts. Despite the increasing popularity of lumen-apposing metal stents (LAMSs), plastic stents may resolve non-necrotic fluid collections effectively with lower costs and no LAMS-specific adverse events. To date, there has been a paucity of data on the appropriate stent type in this setting. This trial aims to assess the non-inferiority of plastic stents to a LAMS for the initial EUS-guided drainage of pseudocysts. METHODS: The WONDER-02 trial is a multicentre, open-label, non-inferiority, randomised controlled trial, which will enrol pancreatic pseudocyst patients requiring EUS-guided treatment in 26 centres in Japan. This trial plans to enrol 80 patients who will be randomised at a 1:1 ratio to receive either plastic stents or a LAMS (40 patients per arm). In the plastic stent group, EUS-guided drainage will be performed using two 7-Fr double pigtail stents. In the LAMS group, the treatment will be performed in the same way except for LAMS use. The step-up treatment will be performed via endoscopic and/or percutaneous procedures at the trial investigator's discretion. The primary endpoint is clinical success, which is defined as a decrease in a pseudocyst size to ≤ 2 cm and an improvement in inflammatory indicators (i.e. body temperature, white blood cell count, and serum C-reactive protein). Secondary endpoints include technical success, adverse events including mortality, pseudocyst recurrence, and medical costs. DISCUSSION: The WONDER-02 trial will investigate the efficacy and safety of plastic stents compared to a LAMS in EUS-guided treatment of symptomatic pancreatic pseudocysts with a particular focus on the non-inferior efficacy of plastic stents. The findings will help establish a new treatment algorithm for this population. TRIAL REGISTRATION: ClinicalTrials.gov NCT06133023 registered on 9 November 2023. UMIN000052647 registered on 30 October 2023. jRCT1032230444 registered on 7 November 2023.

An Exploratory Study of the Potential of Online Counseling for University Students by a Human-Operated Avatar Counselor.

Recently, the use of digital technologies, such as avatars and virtual reality, has been increasingly explored to address university students' mental health issues. However, there is limited research on the advantages and disadvantages of counselors using avatars in online video counseling. Herein, 25 university students were enrolled in a pilot online counseling session with a human counselor-controlled avatar, and asked about their emotional experiences and impressions of the avatar and to provide qualitative feedback on their communication experience. Positive emotions during the session were associated with impressions of the avatar's intelligence and likeability. The anthropomorphism, animacy, likeability, and intelligent impressions of the avatar were interrelated, indicating that the avatar's smile and the counselor's expertise in empathy and approval may have contributed to these impressions. However, no associations were observed between participant experiences and their prior communication with avatars, or between participant experiences and their gender or the perceived gender of the avatar. Accordingly, recommendations for future practice and research are provided. Accumulating practical and empirical findings on the effectiveness of human-operated avatar counselors is crucial for addressing university students' mental health issues.

Virtual indigo carmine chromoendoscopy images: a novel modality for peroral cholangioscopy using artificial intelligence technology (with video).

BACKGROUND AND AIMS: Accurately diagnosing biliary strictures is crucial for surgical decisions, and although peroral cholangioscopy (POCS) aids in visual diagnosis, diagnosing malignancies or determining lesion margins via this route remains challenging. Indigo carmine is commonly used to evaluate lesions during GI endoscopy. We aimed to establish the utility of virtual indigo carmine chromoendoscopy (VICI) converted from POCS images using artificial intelligence. METHODS: This single-center, retrospective study analyzed 40 patients with biliary strictures who underwent POCS using white-light imaging (WLI) and narrow-band imaging (NBI). A cycle-consistent adversarial network was used to convert the WLI into VICI of POCS images. Three experienced endoscopists evaluated WLI, NBI, and VICI via POCS in all patients. The primary outcome was the visualization quality of surface structures, surface microvessels, and lesion margins. The secondary outcome was diagnostic accuracy. RESULTS: VICI showed superior visualization of the surface structures and lesion margins compared with WLI (P < .001) and NBI (P < .001). The diagnostic accuracies were 72.5%, 87.5%, and 90.0% in WLI alone, WLI and VICI simultaneously, and WLI and NBI simultaneously, respectively. WLI and VICI simultaneously tended to result in higher accuracy than WLI alone (P = .083), and the results were not significantly different from WLI and NBI simultaneously (P = .65). CONCLUSIONS: VICI in POCS proved valuable for visualizing surface structures and lesion margins and contributed to higher diagnostic accuracy comparable to NBI. In addition to NBI, VICI may be a novel supportive modality for POCS.

Current status of endoscopic ultrasound-guided antitumor treatment for pancreatic cancer.

Endoscopic ultrasound (EUS) was developed in the 1990s and has significantly transformed pancreatic tumor diagnosis. Subsequently, EUS has rapidly shifted from being a purely diagnostic procedure to being used in a wide range of interventional procedures. Recently, new therapeutic techniques, such as EUS-guided fine needle injection (EUS-FNI) or radiofrequency ablation (RFA), have been developed to deliver various antitumor agents. Despite technological advancements, pancreatic cancer (PC) has a poor prognosis and improvements in treatment outcomes are urgently required. One of the reasons for the limited response to antitumor agents in PC is the abundant desmoplasia and hypovascular nature of the tumor, complicating drug delivery into the tumor. Thus, changing the tumor microenvironment may be important to enhance the effectiveness of chemotherapy, and direct injection of antitumor agents into the tumor under EUS guidance can help overcome treatment challenges in PC. Treatment approaches using the EUS-FNI or RFA technique are expected to further improve the prognosis of PC. Therefore, this study reviewed the existing literature on EUS-guided antitumor therapy, specifically highlighting its application in PC to address the current challenges and to identify potential advancements in the field.

Causal Effects of High Stress Assessed Via Interviews on Mental and Physical Health: Toward Computer Agent-Driven Stress Assessment.

OBJECTIVES: This study investigated the causal effect of high stress assessment via an interview on the mental and physical health of workers 1 month later. METHODS: Stress assessment interviews and feedback were conducted with 50 Japanese workers. In addition to the interviewer, two occupational health professionals assessed participants' stress based on recordings. The average treatment effect was estimated by propensity score matching. RESULTS: High stress, according to the interview-based assessment, had a significant negative causal effect on self-reported well-being 1 month later (95% confidence interval: -3.02, -1.10). In addition, no effect of high stress on stress load, mental and physical symptoms, or burnout was observed. CONCLUSIONS: This study provides important insights into the prognosis of individuals who were assessed through interviews to have high stress. The findings are expected to help automate stress assessments using computer agents.

Detection of residual stones by peroral direct cholangioscopy in patients with intrahepatic stones after hepaticojejunostomy: a prospective study (with video).

BACKGROUND AND AIMS: The difficulty in radiographic confirmation of the presence of stones remains challenging in the treatment of intrahepatic bile duct (IHBD) stones in patients after hepaticojejunostomy (HJ). Peroral direct cholangioscopy (PDCS) enables direct observation of the bile duct and is useful for detecting and removing residual stones; however, its effectiveness is not clearly established in this clinical context. METHODS: This single-center, single-arm, prospective study included 44 patients with IHBD who underwent bowel reconstruction with HJ during the study period. Stone removal was performed by using short-type double-balloon enteroscopy. After balloon-occluded cholangiography, the double-balloon enteroscopy was exchanged for an ultra-slim endoscope through the balloon overtube for PDCS. The primary end point was the rate of residual stones detected by PDCS. Secondary end points were success rate of PDCS, residual stone removal with PDCS, procedure time for PDCS, procedure-related adverse events, and stone recurrence rate. RESULTS: PDCS was successful in 39 (89%) of 44 patients, among whom residual stones were detected in 16 (41%) (95% CI, 28%-54%). Twelve patients (75%) had residual stones <5 mm. Stone removal was successful in 15 (94%) patients, and median procedure time for PDCS was 16 minutes (interquartile range, 10-26 minutes). The rate of procedure-related adverse events was 7% (3 of 44); all adverse events improved with conservative treatment. During the median follow-up of 2.1 years (interquartile range, 1.4-3.3 years), the overall probability of recurrence-free status at 1, 2, and 3 years was 100%, 92%, and 86%, respectively. CONCLUSIONS: PDCS is a safe and effective procedure for complete stone removal in patients with IHBD stones after HJ.

MicroRNA-34a-5p: A pivotal therapeutic target in gallbladder cancer.

Gallbladder cancer incidence has been increasing globally, and it remains challenging to expect long prognosis with the current systemic chemotherapy. We identified a novel nucleic acid-mediated therapeutic target against gallbladder cancer by using innovative organoid-based gallbladder cancer models generated from KrasLSL-G12D/+; Trp53f/f mice. Using comprehensive microRNA expression analyses and a bioinformatics approach, we identified significant microRNA-34a-5p downregulation in both murine gallbladder cancer organoids and resected human gallbladder cancer specimens. In three different human gallbladder cancer cell lines, forced microRNA-34a-5p expression inhibited cell proliferation and induced cell-cycle arrest at the G1 phase by suppressing direct target (CDK6) expression. Furthermore, comprehensive RNA sequencing revealed the significant enrichment of gene sets related to the cell-cycle regulators after microRNA-34a-5p expression in gallbladder cancer cells. In a murine xenograft model, locally injected microRNA-34a-5p mimics significantly inhibited gallbladder cancer progression and downregulated CDK6 expression. These results provide a rationale for promising therapeutics against gallbladder cancer by microRNA-34a-5p injection, as well as a strategy to explore therapeutic targets against cancers using organoid-based models, especially for those lacking useful genetically engineered murine models, such as gallbladder cancer.

Up-regulated expression of two-pore domain K+ channels, KCNK1 and KCNK2, is involved in the proliferation and migration of pulmonary arterial smooth muscle cells in pulmonary arterial hypertension.

Background: Pulmonary arterial hypertension (PAH) is a severe and rare disease in the cardiopulmonary system. Its pathogenesis involves vascular remodeling of the pulmonary artery, which results in progressive increases in pulmonary arterial pressure. Chronically increased pulmonary arterial pressure causes right ventricular hypertrophy and subsequent right heart failure. Pulmonary vascular remodeling is attributed to the excessive proliferation and migration of pulmonary arterial smooth muscle cells (PASMCs), which are induced by enhanced Ca2+ signaling following the up-/down-regulation of ion channel expression. Objectives: In the present study, the functional expression of two-pore domain potassium KCNK channels was investigated in PASMCs from idiopathic PAH (IPAH) patients and experimental pulmonary hypertensive (PH) animals. Results: In IPAH-PASMCs, the expression of KCNK1/TWIK1 and KCNK2/TREK1 channels was up-regulated, whereas that of KCNK3/TASK1 and KCNK6/TWIK2 channels was down-regulated. The similar up-regulated expression of KCNK1 and KCNK2 channels was observed in the pulmonary arterial smooth muscles of monocrotaline-induced PH rats, Sugen 5416/hypoxia-induced PH rats, and hypoxia-induced PH mice. The facilitated proliferation of IPAH-PASMCs was suppressed by the KCNK channel blockers, quinine and tetrapentylammonium. The migration of IPAH-PASMCs was also suppressed by these channel blockers. Furthermore, increases in the proliferation and migration were inhibited by the siRNA knockdown of KCNK1 or KCNK2 channels. The siRNA knockdown also caused membrane depolarization and subsequent decrease in cytosolic [Ca2+]. The phosphorylated level of c-Jun N-terminal kinase (JNK) was elevated in IPAH-PASMCs compared to normal-PASMCs. The increased phosphorylation was significantly reduced by the siRNA knockdown of KCNK1 or KCNK2 channels. Conclusion: Collectively, these findings indicate that the up-regulated expression of KCNK1 and KCNK2 channels facilitates the proliferation and migration of PASMCs via enhanced Ca2+ signaling and JNK signaling pathway, which is associated with vascular remodeling in PAH.

Predicting physical and mental health status through interview-based evaluation of work stress: initial attempts to standardize the interviewing method.

This study conducted an interview-based stress evaluation that considered the psychosocial models of work stress and verified the evaluation's predictive validity. A four-stage assessment comprising a pre-survey, pre-interview questionnaire, stress assessment interview, and post-survey after one month was conducted with 50 Japanese workers. Additionally, 16 occupational health professionals provided stress evaluations based on recorded interview videos. Variables based on intraclass correlation coefficients (ICCs) were computed in multiple ways to compare the agreement among the evaluators. The generalized estimating equation (GEE) was conducted to evaluate the prediction models. The overall ICC among the evaluators was 0.58. The GEE revealed that the mean score of the evaluators in the interview-based stress evaluation significantly predicted psychological symptoms (ß =2.02, p=0.019), burnout (ß =0.77, p<0.001), and well-being (ß =-0.64, p=0.007) one month later, even after adjusting for the self-reported stress levels measured in the pre-survey. The predictive validity of the proposed interview-based stress evaluation was confirmed. Although there are several challenges in standardizing this evaluation, semi-structured interviews are an effective tool for understanding work stress.

MicroRNA-451a inhibits gemcitabine-refractory biliary tract cancer progression by suppressing the MIF-mediated PI3K/AKT pathway.

Gemcitabine is an effective chemotherapeutic agent for biliary tract cancers (BTCs), including gallbladder cancer (GBC) and cholangiocarcinoma (CCA). However, few other effective agents are currently available, particularly for GEM-refractory BTCs. We previously identified microRNA-451a (miR-451a) as a potential therapeutic target in GBC. To elucidate the antineoplastic effects of miR-451a and its underlying mechanisms, we transfected miR-451a into GBC, gemcitabine-resistant GBC (GR-GBC), and gemcitabine-resistant CCA (GR-CCA) cell lines. Furthermore, mimicking in vivo conditions, tumorigenic GBC organoids and three-dimensional (3D) cell culture systems were employed to investigate the anti-proliferative effects of miR-451a on BTCs, and its effect on stem cell properties. We found that miR-451a significantly inhibited cell proliferation, induced apoptosis, and reduced chemoresistant phenotypes, such as epithelial-mesenchymal transition, in both GBC and GR-GBC. The principal mechanism is probably the negative regulation of the phosphatidylinositol 3-kinase/AKT pathway, partially accomplished by directly downregulating macrophage migration inhibitory factor. The Gene Expression Omnibus database revealed that miR-451a was the most significantly downregulated microRNA in CCA tissues. The introduction of miR-451a resulted in similar antineoplastic effects in GR-CCA. Furthermore, miR-451a reduced cell viability in 3D spheroid models and tumorigenic GBC organoids. These findings suggest that the supplementation of miR-451a is a potential treatment strategy for GEM-refractory BTCs.

Cysts or necrotic components in pancreatic ductal adenocarcinoma is associated with the risk of EUS-FNA/B complications including needle tract seeding.

BACKGROUND: EUS-FNA/B for pancreatic ductal adenocarcinoma (PDAC) is generally considered to be safe; however, while the incidence is low, there are occurrences of complications. Among these complications, there are serious ones like needle tract seeding (NTS), and it is not known than which types of tumors have the risks of EUS-FNA/B complications. This study aimed to evaluate the risk of EUS-FNA/B complications in patients with PDAC, focusing on morphological features. METHODS: Overall, 442 patients who underwent EUS-FNA/B for solid pancreatic masses between January 2018 and May 2022 in four institutions were retrospectively surveyed. Finally, 361 patients histopathologically diagnosed with PDAC were analyzed. Among these patients, 79 tumors with cysts or necrotic components were compared with 282 tumors without cysts or necrotic components. The incidence and risk of EUS-FNA/B complications including NTS were evaluated. RESULTS: There were 9 (2.4 %) of total EUS-FNA/B complications and 3 (0.8 %) of NTS. The incidence of total complication rate and NTS in tumors with cysts or necrotic components were significantly higher than in those without cysts or necrotic components (total complication 6.3 % vs. 1.4 %, p = 0.026, NTS 3.7 % vs. 0 %, p = 0.01). The transgastric route of puncture (OR: 93.3, 95 % CI: 3.81-2284.23) and the existence of cysts or necrotic components (OR: 7.3, 95 % CI: 1.47-36.19) were risk factors for EUS-FNA/B complications identified by the multivariate analysis. CONCLUSIONS: We should pay attention to the risks of EUS-FNA/B complications, including NTS, when the tumor has cysts or necrotic components.

Association between BRCA Gene Variants and the Response to Modified FOLFIRINOX in Patients with Unresectable Pancreatic Cancer.

We investigated the effect of modified FOLFIRINOX (mFFX) in unresectable pancreatic cancer by retrospectively analyzing the cases of 43 patients who underwent BRCA testing (germline, n=11; somatic, n=26; both germline and somatic, n=6). The association between BRCA mutations and therapeutic effect was clarified. Six patients tested positive for germline pathogenic variants. Familial pancreatic cancer (33% vs. 3%, p=0.006) and peritoneal disseminated lesions (66% vs. 8%, p<0.001) were significantly more common in patients with germline pathogenic variants. The partial response (PR) rate was 100% in the germline BRCA-positive patients, and 27% in the germline BRCA-negative patients (p<0.001). The median progression-free survival (PFS) was not reached for any germline BRCA-positive patients but was 9.0 months for the germline BRCA-negative patients (p=0.042). Patients with stage IV BRCA-associated pancreatic cancer had better overall survival than those with non-BRCA-associated pancreatic cancer, although the difference was nonsignificant (not reached vs. 655 days, p=0.061). Our results demonstrate that a PR and prolonged PFS can be expected in germline BRCA-positive patients after treatment with mFFX. Our findings also suggest that germline BRCA pathogenic variants may be useful as biomarkers for the therapeutic effect of mFFX in patients with pancreatic cancer.

Optimal liver drainage rate for survival in patients with unresectable malignant hilar biliary obstruction using 3D-image volume analyzer.

Background: Drainage exceeding 50% of total liver volume is a beneficial prognostic factor in patients with unresectable malignant hilar biliary obstruction (UMHBO). However, it is unclear what threshold percentage of total liver volume drained ('liver drainage rate') significantly improves survival in patients with UMHBO who received systemic chemotherapy. Objectives: We aimed to assess the optimal liver drainage rate that improves survival in patients with UMHBO receiving chemotherapy using a three-dimensional (3D)-image volume analyzer. Design: This study was a single-center retrospective cohort study. Methods: Data from 90 patients with UMHBO who received chemotherapy after endoscopic biliary drainage using metal stents at Okayama University Hospital from January 2003 to December 2020 were reviewed. The liver drainage rate was calculated by dividing the drained liver volume by the total liver volume using a 3D-image volume analyzer. The primary endpoint was overall survival by liver drainage rate. The secondary endpoints were time to recurrent biliary obstruction (TRBO) and prognostic factors. Results: The median total liver volume was 1172 (range: 673-2032) mL, and the median liver drainage rate was 83% (range: 50-100). Overall survival was 376 (95% CI: 271-450) days, and patients with >80% drainage (n = 67) had significantly longer survival than those with <80% drainage (n = 23) (450 days versus 224 days, p = 0.0033, log-rank test). TRBO was 201 (95% CI: 155-327) days and did not differ significantly by liver drainage rate. Multivariate Cox proportional hazards regression analysis revealed >80% liver drainage [hazard ratio (HR): 0.35, 95% CI: 0.20-0.62, p = 0.0003] and hilar cholangiocarcinoma (HR: 0.30, 95% CI: 0.17-0.50, p < 0.0001) as significant prognostic factors. Conclusion: In patients with UMHBO scheduled for chemotherapy, >80% drainage is associated with improved survival. Further prospective multicenter studies are needed to verify the results of this study. Trail registration: Okayama University Hospital, IRB number: 2108-011.

The efficacy of non-anesthesiologist-administered propofol sedation with a target-controlled infusion system during double-balloon endoscopic retrograde cholangiopancreatography.

BACKGROUND: The sedation method used during double-balloon endoscopic retrograde cholangiopancreatography (DB-ERCP) differs among countries and/or facilities, and there is no established method. This study aimed to evaluate the efficacy of non-anesthesiologist-administered propofol (NAAP) sedation using a target-controlled infusion (TCI) system during DB-ERCP. METHODS: This retrospective study was conducted between May 2017 and December 2020 at an academic center. One hundred and fifty-six consecutive patients who underwent DB-ERCP were sedated by gastroenterologists using diazepam (n = 77) or propofol with a TCI system (n = 79), depending on the period. The primary endpoint was a comparison of poor sedation rates between the two groups. Poor sedation was defined as a condition requiring the use of other sedative agents or discontinuation of the procedure. Secondary endpoints were sedation-related adverse events and risk factors for poor sedation. RESULTS: Poor sedation occurred significantly more often in the diazepam sedation group (diazepam sedation, n = 12 [16%] vs. propofol sedation, n = 1 [1%]; P = 0.001). Vigorous body movements (3 or 4) (diazepam sedation, n = 40 [52%] vs. propofol sedation, n = 28 [35%]; P = 0.038) and hypoxemia (< 85%) (diazepam sedation, n = 7 [9%] vs. propofol sedation, n = 1 [1%]; P = 0.027) occurred significantly more often in the diazepam sedation group. In the multivariate analysis, age < 70 years old (OR, 10.26; 95% CI, 1.57-66.98; P = 0.015), BMI ≥ 25 kg/m2 (OR, 11.96; 95% CI, 1.67-85.69; P = 0.014), and propofol sedation (OR, 0.06; 95% CI, 0.01-0.58; P = 0.015) were associated factors for poor sedation. CONCLUSIONS: NAAP sedation with the TCI system during DB-ERCP was safer and more effective than diazepam sedation.

A Comparison of the Efficacy of Plastic Stent Placement Above and Across the Sphincter of Oddi for Benign Biliary Hilar Stricture.

We investigated the efficacy and safety of endoscopic plastic stent (PS) placement for hilar benign biliary strictures (BBSs) and compared cases with PS placement above (inside stent, IS) and across (usual stent, US) the sphincter of Oddi. Patients who underwent initial endoscopic PS placement for hilar BBSs between August 2012 and December 2021 were retrospectively analyzed. Hilar BBSs in 88 patients were investigated. Clinical success was achieved in 81 of these cases (92.0%), including 38 patients in the IS group and 43 patients in the US group. Unexpected stent exchange (uSE) before the first scheduled PS exchange occurred in 18 cases (22.2%). The median time from first stent placement to uSE was 35 days. There was no significant difference in the rate and median time to uSE between the two groups. The rates of adverse events such as pancreatitis or cholangitis in the two groups did not significantly differ. However, the rate of difficult stent removal in the IS group (15.8%) was significantly higher than that in the US group (0%) (p=0.0019). US placement is preferable to IS placement for scheduled stent exchange, as it offers the same effectiveness and risk of adverse events with easier stent removal.

Determination of individual factors associated with hallux valgus using SVM-RFE.

INTRODUCTION: This cross-sectional study aimed to determine the factors related to hallux valgus (HV) and their importance using support vector machine-recursive feature elimination (SVM-RFE). METHODS: A total of 864 participants aged ≥ 18 years were enrolled. The Manchester scale was used to determine the presence of HV (summed scores for both feet ≥ 4). The questionnaire included items such as age, sex, height, weight, and foot measurements. These internal factors were analyzed to determine if they are related to HV using SVM-RFE. RESULTS: The results of tenfold cross-validation using SVM-RFE revealed that the numbers of feature selections were 10, 10, and 9 for age, sex, and body weight, respectively, and these factors were shown to be related to HV. HV was found to be more common in women than in men (women, 24.9%; men, 7.6%), but the sex difference was not significant in older people. CONCLUSION: Age and sex were found to be important factors associated with HV identified via feature selection using SVM-RFE.