Although the economic burden of multimorbidity is a growing global challenge, the contribution of multimorbidity in patients with high medical expenses remains unclear. We aimed to clarify multimorbidity patterns that have a large impact on medical costs in the Japanese population. We conducted a cross-sectional study using health insurance claims data provided by the Japan Health Insurance Association. Latent class analysis (LCA) was used to identify multimorbidity patterns in 1,698,902 patients who had the top 10% of total medical costs in 2015. The present parameters of the LCA model included 68 disease labels that were frequent among this population. Moreover, subgroup analysis was performed using a generalized linear model (GLM) to assess the factors influencing annual medical cost and 5-year mortality. As a result of obtaining 30 latent classes, the kidney disease class required the most expensive cost per capita, while the highest portion (28.6%) of the total medical cost was spent on metabolic syndrome (MetS) classes, which were characterized by hypertension, dyslipidemia, and type 2 diabetes. GLM applied to patients with MetS classes showed that cardiovascular diseases or complex conditions, including malignancies, were powerful determinants of medical cost and mortality. MetS was classified into 7 classes based on real-world data and accounts for a large portion of the total medical costs. MetS classes with cardiovascular diseases or complex conditions, including malignancies, have a significant impact on medical costs and mortality.

Background: The potential for developing frailty exists in middle‐aged and older adults. While obesity and metabolic syndrome (MetS) increase the risk of frailty in older adults, this relationship remains unclear in middle‐aged adults, who are prone to developing lifestyle‐related diseases.Objective: To examine the effect of overweight/obesity and MetS on frailty development in middle‐aged and older Japanese adults using real‐world data.Methods: This nationwide cohort study used exhaustive health insurance claims data of 3,958,708 Japanese people from 2015 to 2019 provided by the Japan Health Insurance Association. Participants aged ≥35 and < 70 years who received health checkups in 2015 were included. Multivariate logistic regression was used to assess the effect of body mass index (BMI) and MetS or MetS components (i.e., diabetes, hypertension, and dyslipidemia) in 2015 on frailty risk assessed using the hospital frailty risk score in 2019. Additionally, a subgroup analysis was performed to examine the interaction effects of MetS components and 4‐year weight change (%) on frailty risk among participants who were overweight and obese (BMI ≥25 kg/m²).Results: In 2019, 7204 (0.2%) and 253,671 (6.4%) participants were at high and intermediate frailty risks, respectively. Obesity and MetS were independently associated with intermediate/high frailty risk (odds ratio (OR) 1.36, p < 0.05; OR 1.23, p < 0.05, respectively) and high frailty risk (OR 1.80, p < 0.05; OR 1.37, p < 0.05, respectively) in all participants. Although all MetS components were frailty risk factors, these effects diminished with age in both sexes. Subgroup analysis of patients with diabetes revealed that 5%–10% weight loss was associated with reduced frailty risk in both sexes.Conclusions: Obesity, MetS, and MetS components were independent frailty risk factors in middle‐aged and older Japanese adults. Weight loss of up to 10% over 4 years prevented frailty in patients with diabetes who were overweight and obese.

Promoting subjective well-being is a crucial challenge in aging societies. In 2022, we launched a community-based intervention trial (the Chofu-Digital-Choju Movement). This initiative centered on fostering in-person and online social connections to enhance the subjective well-being of older adults. This paper describes the study design and baseline survey. This quasi-experimental study involved community-dwelling older adults aged 65–84 years in Chofu City, Tokyo, Japan. A self-administered questionnaire was distributed to 3742 residents (1681 men and 2061 women), and a baseline survey was conducted in January 2022. We assessed subjective well-being (primary outcome); psychosocial, physical, and dietary factors; and the use of information and communication technology variables (secondary outcomes) among the participants. After the intervention involving online classes, community hubs, and community events, a 2-year follow-up survey will be conducted to evaluate the effects of the intervention, comparing the intervention group (participants) with the control group (non-participants). We received 2503 questionnaires (66.9% response rate); of these, the analysis included 2343 questionnaires (62.6% valid response rate; mean age, 74.4 (standard deviation, 5.4) years; 43.7% male). The mean subjective well-being score was 7.2 (standard deviation, 1.9). This study will contribute to the development of a prototype subjective well-being strategy for older adults.

Unintentional weight loss is a major frailty component; thus, assessing energy imbalance is essential for institutionalized elderly residents. This study examined prediction errors of the observed energy intake (OEI) against the actual energy intake obtained from the doubly labeled water (DLW) method and clarified the relationship between the energy gap obtained by subtracting total energy expenditure (TEE) from OEI and subsequent weight changes in elderly residents in long-term care facilities. Overall, 46 participants were recruited in Japan. TEE was measured using the DLW method, and OEI was calculated from recipes and plate waste simultaneously over a 14–15-day period at baseline. The total energy intake (TEI_DLW) was determined on the basis of DLW and weight changes during the DLW period. The weight was longitudinally tracked monthly for 12 months in the 28 residents who still lived at the facilities. OEI was higher than TEI_DLW by a mean of 232 kcal/day (15.3%) among 46 residents at baseline. The longitudinal data of 28 residents showed that the energy gap tended to be correlated with the slope of weight change (ρ = 0.337, p = 0.080) and the median value was significantly lower in the weight loss group (152 kcal/day) than in the weight gain group (350 kcal/day) (p < 0.05). In conclusion, weight loss could occur at Japanese long-term care facilities even if the difference obtained by subtracting TEE from OEI was positive because OEI was overestimated by more than 200 kcal/day.

Background/Objectives: Internet use positively impacts mental health in older adults, with health literacy (HL) playing a key role. While social networks may complement individual HL, the role of neighborhood relationships in this association, particularly by gender, remains unclear. This study examined how the association between HL and Internet use among older adults was modified by neighborhood relationships. Methods: Using baseline data from the Chofu–Digital–Choju project, a cross-sectional analysis was conducted on 1955 community-dwelling adults aged 65–84 (889 men and 1066 women). HL was assessed using the Communicative and Critical Health Literacy scale and dichotomized at four points. Neighborhood relationships were categorized as high (visiting/chatting with neighbors) or low (exchanging greetings/no relationship). Gender-stratified logistic regression analyses were performed with Internet use as the dependent variable, with HL, neighborhood relationships, and their interaction as independent variables. Results: Internet user proportion was 55.6% for men and 41.8% for women. HL was positively associated with Internet use in both genders, though patterns differed. Among men, the HL–Internet use association was consistent (OR = 3.09; 95% CI: 2.25–4.24) regardless of neighborhood relationship levels. For women, this association was significantly modified (interaction OR = 0.46, 95% CI: 0.24–0.87). Women with low HL but strong neighborhood relationships showed increased odds of Internet use (OR = 2.08, 95% CI: 1.32–3.26). Conclusions: Gender-specific patterns in HL and neighborhood relationships influence Internet use among older adults. Neighborhood relationships may compensate for low HL in women, underscoring the need for gender-sensitive strategies to promote digital HL.