To update the rurality index for Japan (RIJ) using the most recent national data and to test and evaluate the updated RIJ variants that incorporate alternative distance metrics and a modified classification of remote islands, thereby providing methodological guidance for their use in research and health policy.

Nationwide methodological study.

Japan.

All postal code areas in Japan; analyses were aggregated into municipalities and secondary medical care areas for evaluation.

Six RIJ variants (‘RIJ family’) constructed by combining three distance metrics (direct distance, road-based distance and travel time by car) and two island classifications (original RIJ and modified RIJ), standardised to a continuous 0–100 scale using percentile ranks.

Concordance among RIJ variants was assessed using Spearman’s rank correlation coefficients, quintile reclassification matrices and rank-difference analyses; convergent validity was evaluated using the national physician distribution index. Criterion-related validity was assessed using municipal-level life expectancy for men and women.

All RIJ variants had extremely high concordance (Spearman’s ≥0.99 across all pairwise comparisons). Compared with the previous RIJ classification, >98% of the geographic units remained in the same rurality quintile and

Despite differences in distance metrics and island classification, all RIJ variants captured highly similar underlying dimensions of rurality and demonstrated comparable validity. These findings indicate that rurality measurement in Japan is stable regardless of methodological refinements, allowing RIJ variants to be flexibly selected according to specific research or policy purposes without materially affecting conclusions.

This study aimed to examine rural–urban disparities in healthcare outcomes in Japan using the Rurality Index for Japan (RIJ). It evaluated the association between rurality and mortality from five major diseases prioritised by the Japanese government, accounting for socioeconomic and demographic factors.

An ecological study using publicly available data at municipal and administrative district levels.

All municipalities and administrative districts within government-designated cities in Japan.

A total of 1897 municipalities and administrative districts were analysed, excluding areas with zero population. The total number of the population was approximately 126 million.

Rurality was measured using RIJ.

Standardised mortality ratios (SMRs) were used for acute myocardial infarction (AMI), cerebrovascular diseases (stroke and haemorrhage), cancer and suicide. The standardised claim ratio (SCR) for diabetes outpatient care served as a proxy measure due to the unavailability of mortality data.

Greater rurality, as quantified by RIJ, was associated with higher SMRs for cerebrovascular diseases and male suicide. A dose-response relationship was observed among SMRs for cerebrovascular disease and male suicide, whereas AMI mortality was higher in rural areas but lacked a strict dose-dependent trend. No significant association was found between rurality and cancer mortality or diabetes in outpatient SCR. Additionally, RIJ was positively correlated with the proportion of older adults (Spearman’s =0.67) and the Arial Deprivation Index (=0.55).

These findings highlight the need for targeted rural health policies that improve access to emergency care and mental health services.

Treatment failure remains a major challenge in tuberculosis (TB) management. Rapid and objective assessment of treatment response is essential, as existing tools have limited accuracy and slow turnaround times. The PATHFAST TB LAM Ag assay (PATHFAST-LAM), an automated chemiluminescent enzyme immunoassay, was developed to quantify lipoarabinomannan (LAM) in sputum within 1 hour. Previous studies have shown a strong correlation between sputum LAM concentration and culture-based bacterial load. However, its clinical utility for predicting poor outcomes during treatment has not been prospectively evaluated.

We will conduct a prospective longitudinal study enrolling newly diagnosed, bacteriologically confirmed patients with pulmonary TB at Rhodes Chest Clinic and Mbagathi County Referral Hospital in Nairobi, Kenya. We will follow participants throughout the 6-month treatment course, attempting to collect sputum weekly during weeks 1–4, biweekly during weeks 5–12 and monthly during months 3–6. We will measure LAM concentrations at these time points using the PATHFAST-LAM assay. The primary outcome is to assess whether changes in sputum LAM concentration during the intensive phase (baseline to week 4 and/or week 8) predict a composite poor outcome, defined as positive sputum culture at month 6, treatment failure, death during treatment or relapse within 3 months after treatment completion. The primary endpoint is the area under the curve from the receiver operating characteristic analysis, representing the predictive performance of changes in sputum LAM concentration for the composite poor outcome. We will identify the optimal cut-off value for LAM change and estimate sensitivity and specificity with 95% CIs using 2x2 tables. We will apply an adaptive design that allows sample-size re-estimation after interim analysis.

The study was approved by the Kenya Medical Research Institute (KEMRI/SERU/CRDR/124/5241) and Nagasaki University (250619327). Findings will be disseminated through peer-reviewed publications and scientific meetings.

NCT07157904.

The effect of prophylactic clipping for colorectal cold snare polypectomy (CSP) on delayed bleeding (DB) in patients with antithrombotic drugs remains unverified. The aim of the PERCOLD study is to demonstrate the non-inferiority of DB rates in cases without prophylactic clips compared with cases with prophylactic clips in patients taking antithrombotic drugs for colorectal CSP through randomised controlled trial (RCT).

This study is a multicentre prospective parallel-group RCT phase 3 trial that is being conducted at 14 institutions in Japan at the time of writing this manuscript. After providing consent, patients will undergo screening and assessment for study enrolment eligibility. Patients taking antithrombotic drugs (aged 20 years or older at the time of consent and who have agreed to participate in this study) will be selected if they have a preoperative suspected adenoma (including sessile serrated lesion) with an endoscopic diameter of

The trial protocol has been approved by the Chiba University Certified Clinical Research Reviewer Board (CRB3180015), which serves as the central ethics committee, and registered with Japan Registry of Clinical Trials. The current protocol V.1.7, dated 4 October 2024. Written informed consent for participation in the study will be obtained from all participating patients. All participating institutions have formally agreed to conduct the study in accordance with this central approval, and local site permissions were obtained as required by each institution. The results of this study will be submitted for publication in international peer-reviewed journals and the key findings will be presented at international scientific conferences.

Japan Registry of Clinical Trials (jRCT1032230086).