Hwa-Young Lee

BACKGROUND Obesity is a major public health concern, yet conventional anthropometric indicators such as body mass index (BMI) show inconsistent associations with mortality, including the obesity paradox. OBJECTIVE This study introduces the Body Volume Index (BVI)—a novel 3D ellipsoid shape-based obesity indicator capturing central body dimensions relative to body mass—and evaluates its performance in predicting mortality against established measures. METHODS We analyzed data from 288,331 Korean adults in the National Health Insurance Service–National Sample Cohort (2009–2019). Five obesity indicators—BMI, waist-to-height ratio (WHtR), a body shape index (ABSI), body roundness index (BRI), and BVI—were categorized into sex-specific deciles (Q1-Q10, with Q5 as the reference). Associations with all-cause and cancer-specific mortality were assessed using multivariable Cox proportional hazards models adjusted for sociodemographic factors, health behaviors, and comorbidities. RESULTS In fully adjusted models, BMI showed a reverse J-shaped association with all-cause and cancer-specific mortality. WHtR and BRI paradoxically exhibited inverse or non-monotonic associations with mortality outcomes (e.g., for WHtR among men, adjusted hazard ratio [aHR] of all-cause mortality:1.27, 95% CI 1.13–1.42 for Q1 vs. Q5). Conversely, ABSI and BVI showed consistent positive linear trends with all-cause mortality in both sexes (e.g., for men in Q10 vs. Q5, aHR 1.58, 95% CI 1.41–1.77 for ABSI; and aHR 1.20, 95% CI 1.09–1.32 for BVI). Although ABSI showed steeper gradients for all-cause mortality than BVI, its association with cancer mortality was more variable. CONCLUSIONS BVI demonstrated stable positive associations with mortality outcomes alongside ABSI. Given its straightforward geometric formulation and wider numerical variability, BVI may offer favorable practical feasibility for risk stratification in large-scale epidemiologic contexts.

Background: People with disabilities face a substantial psychiatric burden, yet the longitudinal dynamics of mental health outcomes following disability onset remain poorly understood. We investigated the temporal trajectories of excess risk of incident depression and suicide mortality following disability onset.Methods: In this nationwide, population-based cohort study, we used linked data from the National Health Insurance Service and National Disability Registry in South Korea. We identified individuals with newly registered disabilities between 2009 and 2023 and followed them over time after disability onset. Cox proportional hazards regression models were used to estimate adjusted hazard ratios (aHRs) and 95% CIs for incident depression and suicide mortality across prespecified periods after disability onset (0–1, 1–3, 3–5, and >5 years). We further examined temporal trajectories by disability type and sociodemographic characteristics.Findings: The excess risk of incident depression peaked during the first year after disability onset (0–1 year: aHR 3·89, 95% CI 3·83–3·96) and attenuated thereafter. In contrast, suicide mortality followed a time-lagged, inverted U-shaped trajectory, peaking during the 1–3-year period (aHR 2·08, 95% CI 1·92–2·26). This temporal divergence persisted after exclusion of individuals with primary mental health-related disabilities. Temporal patterns of suicide risk varied substantially by disability type: whereas several categories peaked during the 1–3-year period, others showed delayed peaks at 3–5 years or persistently elevated risk beyond 5 years. (Respiratory disease, ostomy, and epilepsy). The peak in suicide risk occurred earlier among men and individuals in lower-income groups (1–3 years) than among women and individuals in higher-income groups (3–5 years).Interpretation: Disability onset was associated with distinct and time-dependent psychiatric trajectories, characterised by an acute increase in depression risk followed by a delayed peak in suicide mortality. The timing and persistence of suicide risk varied by disability type and sociodemographic characteristics. These findings suggest that mental health surveillance and suicide prevention following disability onset should extend beyond the immediate post-onset period and incorporate phase-specific, disability-specific, and sociodemographically tailored approaches.

Background: Postnatal care (PNC) plays a crucial role in averting newborn mortality, yet its use remains low, particularly in regions with the highest mortality. While demographic and social determinants of PNC use have been well studied and have informed current strategies focused on changing care-seeking behaviors, the stagnating decline in neonatal mortality highlights the need for upstream and system-wide approaches to increase PNC uptake. Limited evidence exists to guide system-level reforms; therefore, we investigated whether health systems that ensure high-quality perinatal care are associated with increased use of PNC. Methods and findings: We performed a cross-sectional observational study using Demographic and Health Survey data from 38 countries that had not met SDG neonatal mortality targets by 2020. The study population comprised women aged 15–49 years whose most recent live birth occurred within five years preceding the survey. We employed logistic regression models with country fixed effects to examine associations between: (1) perinatal service utilization, (2) service quality; and their relationship with postnatal checkups for newborns within 28 days. We analyzed utilization-quality interactions to determine how the effects of service coverage on PNC use varied by care quality and conducted wealth-stratified analyses to assess how quality effects on PNC use differed across socioeconomic groups. High-quality perinatal care was associated with a 2-fold increase in the probability of postnatal checkups within 28 days (0.406 in the highest quality tertile versus 0.221 in the lowest quality tertile). For mothers who received the lowest tertile of service quality, full utilization of perinatal services yielded negligible changes in postnatal checkup probability (0.217 to 0.216). Conversely, for mothers who received the highest quality of antenatal and perinatal care, full access to perinatal care improved the probability of postnatal check-ups (0.392 to 0.428). Notably, women in the lowest wealth quintile experienced a substantial increase in postnatal checkup probability from 0.224 to 0.481 between low and high-quality care cohorts, while this differential was less pronounced in the highest wealth quintile (0.236 to 0.450). Key limitations include restricted quality indicators, potential recall bias from self-reported measures, limited information on follow-up care, and the cross-sectional nature of the data, which limits causal interpretation. Conclusions: Our interaction analysis reveals a critical insight: high-quality care substantially enhanced the magnitude of the association between expanded perinatal service use and PNC use, whereas increased utilization alone was not linked to higher PNC uptake. Notably, the impact of improved care quality was most pronounced among the lowest wealth groups, highlighting its potential as a mechanism for promoting equity. By demonstrating the central role of care quality in promoting PNC utilization, particularly among disadvantaged populations, our findings suggest that improving health system quality could be a more effective strategy for achieving universal maternal healthcare coverage than traditional access-focused approaches.

Objective: Although socioeconomic status has been linked to various rheumatoid arthritis (RA)-related outcomes, evidence on the association of sustained income status with mortality among patients with RA remains limited. Methods: We followed a nationally representative cohort of 50 600 Korean adults aged ≥40 years newly diagnosed with RA between 2010 and 2017 through 31 December 2020. Income status, based on monthly health insurance premiums, was tracked over the 5-year period preceding diagnosis. Primary exposure included the cumulative years in a low- or high-income status. The outcome was all-cause mortality. Cox proportional hazards models were used to estimate HRs after adjusting for sociodemographic, behavioural and clinical covariates. We conducted a comprehensive stratified analysis using a range of relevant factors. Results: Sustained low-income status was significantly associated with increased mortality in a dose–response manner among patients aged <65 years, even after adjusting for income status at diagnosis (p for trend=0.011 vs 0.374 in older patients). Sustained high-income status was associated with reduced mortality in both age groups, with a stronger association observed in younger patients (adjusted HR (95% CI) for 5-year high-income exposure: 0.50 (0.38–0.64) in patients aged <65 years versus 0.74 (0.62–0.88) in patients ≥65 years). Rural residence further amplified the adverse effects of prolonged low-income exposure. Conclusions: Persistent low-income status increases mortality risk among younger patients with RA, a group often overlooked by policy interventions. Policies that address the sustained economic disadvantages beyond short-term assistance are required.

Background: Although often associated with ageing, disability is becoming increasingly prevalent among young adults. While disability can pose a substantial psychological burden for young adults on critical pathways to establish the foundations for their future, the mental health risks faced by this population remain underexplored. Aims: This study aimed to (1) assess the association between disability – including its presence, severity and type – and the risk of depressive and anxiety disorders, and (2) examine whether this association varies across sociodemographic factors, health behaviours and comorbidities in a young adult population. Methods: We conducted a population-based cohort study using linked data from the National Disability Registry and the National Health Insurance Database of South Korea. A total of 6,058,290 individuals aged 20–39 years who underwent health check-ups between 2009 and 2012 were followed through 2022. Cox proportional hazards models were used to estimate adjusted hazard ratios (aHRs) for depressive and anxiety disorders. Results: Individuals with disabilities had significantly higher risks of depressive (aHR: 1.58, 95% CI: 1.55–1.60) and anxiety disorders (aHR: 1.50, 95% CI: 1.42–1.59). Increased risks were consistently observed across various disability types with the highest risk observed for mental health-related disabilities in depression (aHR: 4.98, 95% CI 4.62–5.37) and epilepsy-related disabilities in anxiety disorders (aHR: 12.05, 95% CI 8.73–16.63). Subgroup analyses revealed stronger associations among individuals in their 20s, low-income groups, non-smokers and those abstaining from alcohol, compared to their respective counterparts. Conclusions: Young adults with disabilities, a population that has been relatively overlooked in policy discussions, warrant greater policy attention in relation to their mental health.

Lee HY, et al. J Korean Med Sci. 2026 May;41:e133. https://doi.org/10.3346/jkms.2026.41.e133

Background: South Korea experiences the highest diabetes-related hospitalization rates among OECD countries. Although integrated primary care could potentially lower preventable hospitalizations and healthcare costs, the limited uptake of a usual source of care (USC) and underdeveloped primary care services in Korea have impeded progress, and the role and functions of primary care remain insufficiently defined. Methods: This study investigated how having a USC affects medical expenditures in adults with diabetes by using Korea Health Panel data from 2019 to 2022, spanning the pre-pandemic (2019) and pandemic (2020–2022) periods. The analysis included 6,144 individuals. The main independent variable was the type and quality of USC, categorized into three groups: no USC, place-only USC, and physician-based USC. Quality was assessed by patient-reported comprehensiveness and coordination, combined into an integrated quality index. We applied panel regression analysis using the Hausman–Taylor estimation technique to address both time-varying and time-invariant covariates while mitigating endogeneity concerns. Results: Between 2019 and 2022, the proportion of individuals with a physician at a regular location serving as their USC increased from 58.5% to 66.1%, while the proportion without a physician as their USC decreased from 15.1% to 10.9%, with larger variation among vulnerable populations. The physician-based USC group consistently incurred higher absolute expenditures but showed the smallest relative increase during the pandemic, compared with sharp rises in the no-USC and place-only USC groups. Adults with diabetes whose USC was a high-quality primary care physician—defined by favorable patient ratings of comprehensiveness and coordination—were associated with approximately 13.1% lower healthcare expenditures compared to those lacking a physician as their USC (β = − 0.140, P = 0.006). Moreover, community clinic–based physicians as USC were associated with lower expenditures, while hospital-based USC was associated with higher costs, though not statistically significant. Conclusion: These findings underscore the importance of increasing access to high-quality primary care physicians as USC to optimize chronic disease management and maintain sustainable healthcare systems.

The global rise in obesity prevalence and the incidence of early-onset cancer (diagnosed between 20 and 49 years of age) is a serious public health concern. We, therefore, evaluated the recent global trends in the incidence of early-onset obesity-related cancers and compared them to those of non-obesity-related cancers. We obtained age-standardized incidence rates of early-onset cancers diagnosed between 2000 and 2012 in 44 countries from the Cancer Incidence in Five Continents database. Using joinpoint regression models, we calculated the average annual percentage changes (AAPCs) and their corresponding 95% confidence intervals (95% CIs) for combined and individual categories of obesity-related cancers (11 and 9 cancer types in females and males, respectively) and non-obesity-related cancers (12 cancer types in both females and males). Differences in the AAPC were assessed by comparing 95% CIs, where nonoverlapping 95% CIs were considered statistically significantly different. We observed statistically significant positive AAPCs for early-onset obesity-related cancers in all available countries combined among females (global AAPC, 4.3%; 95% CI, 4.1–4.6%) and males (global AAPC, 1.4%; 95% CI, 1.2–1.7%). When analyzed by countries, we observed statistically significant positive AAPCs in 26 countries among females and 11 countries among males. AAPCs for early-onset obesity-related cancers were statistically significantly higher than those of non-obesity-related cancers in several regions, especially North America and Oceania. In conclusion, this study indicates that the incidence of early-onset obesity-related cancers exhibited a more pronounced increasing trend than non-obesity-related cancers among both sexes in many countries and regions.