Validity of claims-based definition of number of remaining teeth in Japan: Results from the Longevity Improvement and Fair Evidence Study.

BACKGROUND: Secondary healthcare data use has been increasing in the dental research field. The validity of the number of remaining teeth assessed from Japanese dental claims data has been reported in several studies, but has not been tested in the general population in Japan. OBJECTIVES: To evaluate the validity of the number of remaining teeth assessed from Japanese dental claims data and assess its predictability against subsequent health deterioration. METHODS: We used the claims data of residents of a municipality that implemented oral health screening programs. Using the number of teeth in the screening records as the reference standard, we assessed the validity of the claims-based number of teeth by calculating the mean differences. In addition, we assessed the association between the claims-based number of teeth and pneumococcal disease (PD) or Alzheimer's disease (AD) in adults aged ≥65 years using Cox proportional hazards analyses. RESULTS: Of the 10,154 participants, the mean number of teeth assessed from the claims data was 20.9, that in the screening records was 20.5, and their mean difference was 0.5. During the 3-year follow-up, PD or AD onset was observed in 10.4% (3,212/30,838) and 5.3% (1,589/30,207) of participants, respectively. Compared with participants with ≥20 teeth, those with 1-9 teeth had a 1.29 (95% confidence interval [CI]: 1.17-1.43) or 1.19 (95% CI: 1.04-1.36) times higher risk of developing PD or AD, respectively. CONCLUSION: High validity of the claims-based number of teeth was observed. In addition, the claims-based number of teeth was associated with the risk of PD and AD.

The association between objective and subjective oral health conditions and the presence of anorexia of aging among Japanese older Adults1.

Anorexia of aging is a risk factor for malnutrition among older adults. This study aimed to evaluate the association between objective and subjective oral health and anorexia among independent older adults. This cross-sectional study targeted independent older adults aged ≥65 years who participated in the Japan Gerontological Evaluation Study conducted in 2022. The outcome variable was the presence of anorexia, as assessed by the Simplified Nutritional Appetite Questionnaire. Exposure variables were dental status (≥20 teeth, 10-19 teeth with/without dentures, and 0-9 teeth with/without dentures) as objective oral health and oral health-related quality of life measured by five items of the short version of the Oral Impacts on Daily Performances (OIDP) (eating, speaking, smiling, emotional stability, and enjoying with others) as subjective oral health. We fitted the Poisson regression model, including possible confounders, and estimated prevalence ratios (PRs) and 95% confidence intervals. Among 19,787 participants (mean age: 74.6 years [1SD = 6.2], male: 48.5%), 9.0% were classified as having anorexia. After adjusting possible confounders, those with ≤19 teeth had a higher proportion of experiencing anorexia compared to those with ≥20 teeth; however, the association was less pronounced among those with dentures (0-9 teeth with dentures: PR = 1.48 [1.31-1.68], and 0-9 teeth without dentures: PR = 2.08 [1.65-2.63]). Even after adjusting for dental status, each item of OIDP was significantly associated with the presence of anorexia (all p < 0.05). The results showed that both objective and subjective poor oral health were significantly associated with a higher probability of developing anorexia of aging. Therefore, improving both objective and subjective oral health through appropriate dental care could contribute to maintaining appetite in later life.

Changes in the utilization of outpatient and visiting dental care and per-attendance care cost by age groups during COVID-19 pandemic waves in Japan: A time-series analysis from LIFE study.

BACKGROUND: The influence of the coronavirus disease (COVID-19) pandemic on dental care utilization may have differed according to individual characteristics or type of dental care provision. This study aimed to evaluate the changes in dental care utilization and per-attendance costs by age group and type of dental care during the COVID-19 pandemic in Japan. METHODS: This time-series study used healthcare insurance claims data from 01/07/2019 to 09/27/2021 (143 weeks) from nine municipalities in Japan. Dental care utilization rate per week and average dental care cost per attendance by age groups (0-19y/20-64y/65-74y/≥ 75y) and types of dental care (outpatient/visiting) were used as outcome variables. COVID-19 pandemic waves in Japan were used as predictors: 1st (03/23/2020-05/17/2020), 2nd (06/22/2020-09/27/2020), 3rd (10/26/2020-02/21/2021), 4th (02/22/2021-06/07/2021), and 5th (07/05/2021-09/13/2021) waves. Fixed effect models were employed to estimate the proportional changes. RESULTS: In the fixed effect model, we observed large declines in dental care utilization during the 1st (17.0-22.0%) and 2nd waves (3.0-13.0%) compared to the non-pandemic wave period in all age groups. In contrast, the average dental care cost per attendance increased in all age groups by 5.2-8.6% during the 1st wave. CONCLUSIONS: During the initial wave of the COVID-19 pandemic in Japan, dental care utilization decreased in all age groups, whereas the average dental care cost per attendance increased. The COVID-19 pandemic may have changed the dental care provision pattern towards less frequent and more concentrated dental care to avoid the risk of infection.

Dental prosthesis use moderates association between tooth loss and risk of depressive symptoms in older adults with severe tooth loss: The JAGES cohort trial.

PURPOSE: Depression is a leading cause of disability. Although tooth loss increases the risk of depressive symptoms, it is unclear whether dental prosthesis use moderates this risk. This study aimed to investigate whether dental prosthesis use moderates the association between tooth loss and new depressive symptoms in older adults. METHODS: This cohort study used data from the 2016 and 2019 Japan Gerontological Evaluation Study (JAGES). The participants were independent older adults aged ≥65 years without depressive symptoms in 2016. The onset of depressive symptoms in 2019 was the outcome variable. The explanatory variables were dental status (≥20 teeth, 10-19 teeth with or without dental prostheses, and 0-9 teeth with or without dental prostheses) in 2016. Risk ratios (RRs) and 95% confidence intervals (CIs) were estimated using Poisson regression models with potential confounders as covariates. RESULTS: The analysis included 50,169 participants (mean age: 72.8 [standard deviation, 5.4] years). During follow-up, the incidence of depressive symptoms was 11.3%. Compared to those who had ≥20 teeth, the RR of depressive symptom onset was highest among those who had 0-9 teeth without dental prostheses (RR, 1.27; 95% CI, 1.04-1.56), after the adjustment for confounders. However, this risk was lower in those with 0-9 teeth and dental prostheses (RR, 1.08; 95% CI, 1.01-1.15). CONCLUSIONS: These data highlight the potential of dental prostheses as an important factor in reducing the risk of depressive symptoms among individuals with severe tooth loss.

Differences in prevalence of self-reported oral hypofunction between older adult patients with rheumatoid arthritis and the general older population: A cross-sectional study using propensity score matching.

OBJECTIVE: To examine the association between rheumatoid arthritis (RA) and oral hypofunction (OHF) using propensity score matching (PSM) to adjust for differences between older adults with RA and the general older adult population. METHODS: We conducted a cross-sectional survey among 189 older adults with RA in 2019 (mean age, 71.9 ± 3.6) and 47 178 independent older adult residents in 2016 (mean age, 71.6 ± 4.0), respectively. The questionnaire covered information on socio-demographic characteristics and OHF for both groups. Age, sex, educational level and smoking history were used to determine PSM. Prevalence ratios (PRs) and 95% confidence intervals (CIs) of self-reported OHF (fewer remaining teeth, decreased masticatory function, deterioration of swallowing function and oral dryness) were estimated using Poisson regressions. RESULT: OHF was observed in 44.4% of patients with RA and 27.5% of residents. Before PSM, the prevalence of OHF among patients with RA was higher than that of residents (PR, 1.75; 95% CI, 1.50-2.05). After PSM, there were 189 patients with RA and residents, and the prevalence of OHF among patients with RA was still higher (PR, 1.61; 95% CI, 1.22-2.13). Poisson regression showed that the prevalence of 19 or fewer teeth (PR, 1.06; 95% CI, 0.82-1.36), difficulties eating tough foods (PR, 1.18; 95% CI, 0.90-1.55), difficulties swallowing tea or soup (PR, 1.77; 95% CI, 1.19-2.63), and dry mouth (PR, 2.79; 95% CI, 1.90-4.07) was higher among patients with RA than residents. CONCLUSION: Compared with the general older adult population, patients with RA have a higher prevalence of self-reported OHF.

Tooth loss mediates the association between smoking and an increased risk of dementia among older adults: The JAGES prospective cohort study.

AIM: Tooth loss has various causes; however, its cause-specific effects on health outcomes remain unclear. This study evaluated whether the association between past/current smoking and risk of dementia was mediated by tooth loss. MATERIALS AND METHODS: This 9-year-follow-up prospective cohort study targeted adults aged ≥65 years. Dementia incidence during 2013-2019, smoking status (never, past/current) in 2010 and the number of remaining teeth (≤19, ≥20) in 2013 were the outcome, exposure and mediator, respectively. We used causal mediation analysis to fit the Cox proportional hazards model and estimated the hazard ratio (HR) and 95% confidence interval (CI) of the natural indirect effect (NIE) of smoking on dementia incidence through tooth loss and their mediated proportions. RESULTS: Among 32,986 participants (mean age 72.6 years [1 SD = 5.4]; men 48.4%), the dementia incidence during follow-up was 2.11/100 person-years. Tooth loss significantly mediated the association between past/current smoking and dementia incidence; the NIE of fewer remaining teeth for past/current smokers compared to never smokers was HR = 1.03 (95% CI: 1.02-1.05), and the mediated proportion was 18.0%. CONCLUSIONS: Tooth loss significantly mediates the association between past/current smoking and an increased risk of dementia among older adults.

Bivalent mRNA vaccine effectiveness against COVID-19 among older adults in Japan: a test-negative study from the VENUS study.

BACKGROUND: Bivalent COVID-19 vaccines have been implemented worldwide since the booster vaccination campaigns of autumn of 2022, but little is known about their effectiveness. Thus, this study holistically evaluated the effectiveness of bivalent vaccines against infection in older adults in Japan. METHODS: We adopted the test-negative design using COVID-19 test data of individuals, aged ≥ 65 years, residing in three municipalities in Japan, who underwent tests in medical institutions between October 1 and December 30, 2022. Logistic regression analyses were conducted to estimate the odds of testing positive according to vaccination status. Vaccine effectiveness was defined as (1 - odds ratio) × 100%. RESULTS: A total of 3,908 positive and 16,090 negative results were included in the analyses. Receiving a bivalent dose in addition to ≥ 2 monovalent doses was 33.6% (95% confidence interval [CI]: 20.8, 44.3%) more effective than receiving no vaccination, and 18.2% (95% CI: 9.4, 26.0%) more effective than receiving ≥ 2 monovalent doses but not receiving a bivalent vaccination. In addition, the effectiveness peaked at 14-20 days after administration and then gradually declined over time. Furthermore, a bivalent booster dose provided 18.6% (95% CI: 9.9, 26.5%) additional protection among those vaccinated with ≥ 2 monovalent doses, in the absence of a previous infection history. However, we did not find sufficient evidence of effectiveness of bivalent vaccines among previously infected older adults. CONCLUSIONS: Bivalent vaccines are effective against COVID-19 infections among older adults without a history of infection.

Poor oral health and dementia risk under time-varying confounding: A cohort study based on marginal structural models.

BACKGROUND: Bidirectional association between oral health, including tooth loss and oral hypofunction, and cognitive impairment can induce time-varying confounding in association with dementia. This study aimed to investigate the association between oral health and the development of dementia among older adults, considering cognitive impairment as a time-varying confounder. METHODS: This nine-year follow-up cohort study targeted independent older adults aged ≥65 years who participated in the Japan Gerontological Evaluation Study. The exposure variables were self-reported poor oral health (≤19 remaining teeth, edentulousness, chewing difficulty, swallowing problems, and xerostomia), which were assessed in 2010 and 2013. The outcome variable was the incidence of dementia between 2013 and 2019, which was obtained from the municipalities' administrative database. Furthermore, in 2010 and 2013, we considered cognitive impairment as a time-varying confounder and treated it based on a marginal structural model (MSM), including possible baseline confounders. Oral health and cognitive impairment were assessed using the items of Kihon checklist. We employed a Cox proportional hazards model with a stabilized inverse probability weight and estimated hazard ratios (HRs) and 95% confidence intervals (CIs). RESULTS: Among 37,556 participants (mean age: 72.8 years [1 SD = 5.5], males: 46.8%), the dementia incidence rate was 2.2/100 person-year. The proportions of those with ≤19 remaining teeth, edentulousness, chewing difficulty, swallowing problems, and xerostomia were 61.3%, 11.0%, 24.4%, 14.7%, and 19.2%, respectively. From the regression analysis based on MSM, ≤19 remaining teeth (HR = 1.12, 95% CI = 1.03-1.23), edentulousness (HR = 1.20, 95% CI = 1.09-1.32), chewing difficulty (HR = 1.11, 95% CI = 1.02-1.21), and xerostomia (HR = 1.10, 95% CI = 1.01-1.20) were significantly associated with an increased risk of dementia; however, swallowing problems were not significantly associated with dementia onset (p > 0.05). CONCLUSIONS: Even after considering time-varying confounding by cognitive function at baseline and follow-up, we observed significant associations between poor oral health and increased risk of dementia among older adults.

Association between dietary pattern and insomnia symptoms among independent older adults: A cross-sectional study based on JAGES.

BACKGROUND: Poor diet can cause sleep disorders; however, this association has not been established in older populations. This study investigated the association between dietary patterns and insomnia symptoms in independent older adults. METHODS: This cross-sectional study targeted independent older Japanese adults aged ≥74 years. We used insomnia symptoms classified into three domains: difficulty initiating sleep (DIS), difficulty maintaining sleep (DMS), and insomnia. These symptoms were assessed as dependent variables by a self-reported questionnaire. Dietary patterns (DP), identified by principal component analysis of a self-administered diet history questionnaire, were used as independent variables. Poisson regression analysis was used to estimate the prevalence ratios and 95% confidence intervals with adjustment for potential confounders. RESULTS: Among 1,311 participants (mean age = 80.1; women, 48.5%), we identified three dietary patterns: DP1 was characterized by a high intake of vegetables, soy products, and fruits and a low intake of rice; DP2 was characterized by a high intake of fish, chicken, processed meat, and noodles and a low intake of soy products; and DP3 was characterized by a lower intake of fruits and confectionaries. Higher DP1 scores were significantly associated with a lower prevalence of DIS (p-for-trend = 0.012). A higher DP2 score was significantly associated with a higher prevalence of insomnia (p-for-trend = 0.032). There was no significant association between DP3 and insomnia symptoms (p-for-trend >0.05). CONCLUSION: Our results highlighted that a dietary pattern with a high intake of vegetables, soy products, and fruits may contribute to reducing insomnia symptoms among independent older adults.

Does online communication mitigate the association between a decrease in face-to-face communication and laughter during the COVID-19 pandemic? A cross-sectional study from JACSIS study.

Laughter has a protective effect on human health. The spread of coronavirus disease 2019 (COVID-19) has changed opportunities for face-to-face communication and might decrease opportunities for laughter. This cross-sectional study aimed to investigate whether the decrease in face-to-face communication during the COVID-19 pandemic is associated with a decrease in laughter. Additionally, we investigated whether an increase in online communication mitigates this association. Data from the "Japan COVID-19 and Society Internet Survey (JACSIS)," conducted between August and September 2020, were used. Participants aged 15-79 years were included in this study. The outcome was a decrease in laughter before the onset of the COVID-19 pandemic. The explanatory variables were decreased face-to-face communication with friends and increased online communication (text message, telephone, and video contact). Causal mediation analysis was used to calculate prevalence ratios (PRs) and 95 % confidence intervals (CIs) of the controlled direct effects of increased online communication. Furthermore, the proportions eliminated (PEs) by an increase in online communication were calculated. Among the 25,482 participants, 40.4 % had decreased face-to-face communication and 21.4 % had a decreased frequency of laughter. After adjusting for confounders, a decrease in face-to-face communication was significantly associated with a decrease in laughter (PR = 1.62, 95 %CI = 1.55-1.70). PEs for decrease in laughter were 27.2 % (95 %CI = -2.0 to 56.4) for text-based communication, 36.1 % (95 %CI = 12.3-59.8) for telephone-based communication, and 28.6 % (95 %CI = 0.6-56.6) for video-based communication. Although a decrease in face-to-face communication was associated with a decrease in laughter during the COVID-19 pandemic, online communication, particularly telephone-based communication, mitigated this association.

Oral Hypofunction and Risk of Weight Change among Independent Older Adults.

Oral health is essential for nutritional status; however, little is known about its association with weight change. This study aimed to investigate whether the risk of weight change differs according to the presence of each important component of oral hypofunction (fewer remaining teeth, low chewing efficiency, swallowing problems, and xerostomia) among independent older adults. This was a three-year follow-up cohort study based on self-reported questionnaires. The participants were independent older adults aged ≥65 from the Japan Gerontological Evaluation Study (JAGES). We used >5% weight loss/gain during follow-up as the outcome variables, and the number of remaining teeth (≥20/10-19/0-9), the presence of chewing difficulty, swallowing problems, and xerostomia (yes/no) as the exposure variables. We fitted the Poisson regression model, including possible confounders to estimate the risk ratios (RRs) and 95% confidence intervals (CIs). For weight loss, RRs were significantly higher among those with 0-9 remaining teeth (RR = 1.17; 95% CI = 1.11-1.23), chewing difficulty (RR = 1.12; 95% CI = 1.07-1.16), and xerostomia (RR = 1.11; 95% CI = 1.06-1.16), but there was no significant association with swallowing problems (RR = 1.01; 95% CI = 0.97-1.06). For weight gain, we also found similar associations with oral hypofunction. Oral hypofunction among older adults could have non-negligible health impacts on nutritional status.

Reduced number of teeth with and without dental prostheses and low frequency of laughter in older adults: Mediation by poor oral function.

PURPOSE: Laughter is expected to have health-protective effects, but the potential link between tooth loss and laughter remains unclear. Therefore, this study aimed to examine the association between tooth loss and a low frequency of laughter among older adults in Japan, to elucidate whether this association could be mitigated by dental prostheses, and to evaluate the magnitude of the association mediated by poor oral function. METHODS: We used cross-sectional data from 157,708 functionally independent participants aged ≥65 years (46.3% male) from the Japan Gerontological Evaluation Study. A modified Poisson regression model was applied to examine the association between the number of remaining teeth (≥20/10-19/0-9), dental prostheses use, and infrequent laughter (i.e., laughing never or almost never). Causal mediation analysis was performed to assess whether the association was mediated by difficulties in eating hard foods, choking, or dry mouth. RESULTS: Among the participants, 9,129 reported infrequent laughter. Participants with ≤9 and 10-19 teeth who did not use dental prostheses had a 1.29 and 1.14 times higher likelihood of infrequent laughter than those with ≥20 teeth, respectively. Furthermore, difficulty eating hard foods, choking, and dry mouth mediated 22.8%, 0.4%, and 4.3% of the association between fewer remaining teeth and infrequent laughter, respectively. Meanwhile, we did not find evidence for the differences in infrequent laughter between participants with ≤19 teeth using dental prostheses and those with ≥20 teeth. CONCLUSIONS: Tooth loss among individuals without dental prostheses was associated with infrequent laughter, and this association was mediated by poor oral function.

Cooking skills modify the association between oral health and mortality.

Poor oral health has been linked to an increased risk of mortality. People with good cooking skills may be able to cope with problems caused by oral dysfunction, such as restricted food choice. This study investigated whether cooking skills modified the association between oral health status and mortality. A 3-year follow-up was conducted among participants of the Japan Gerontological Evaluation Study, a population-based cohort study of Japanese adults aged 65-101 years. Oral health assessment comprised number of teeth and three oral functions (awareness of swallowing difficulty, decline in masticatory function, and dry mouth). Cooking skills were assessed using a valid scale adapted for Japanese participants. Mortality from 2016 to 2019 was analysed for 10,121 respondents. Cox regression models were used to estimate hazard ratios for mortality risk adjusting for potential confounders, including sociodemographic factors and health status. During the follow-up, there were 488 deaths (4.8% of all participants). Both fewer teeth and poor oral function were associated with a greater mortality risk. Cooking skills modified the association only for oral function. Stratification by cooking skill score showed that the hazard ratios for ≥2 oral difficulties (vs. none) was 2.06 (95% confidence interval: 1.43-2.96) among those with low cooking skills and 1.25 (95% confidence interval: 0.92-1.71) among those with high cooking skills after adjusting for potential confounders. Improving cooking skills may be key to mitigating health risks owing to poor oral functions.

Exploring the relationship between oral health and multiple health conditions: An outcome-wide approach.

PURPOSE: A growing body of evidence suggests that oral health is associated with a wide range of health outcomes; however, opinions tend to vary because of inconsistent findings. This study aimed to simultaneously examine the association between oral health status and multiple health and well-being indicators using outcome-wide epidemiology. METHODS: Data were obtained from the Japan Gerontological Evaluation Study. Oral health status was categorized as: ≥20 teeth, 10-19 teeth with dental prosthesis, 0-9 teeth with prosthesis, 10-19 teeth without prosthesis, and 0-9 teeth without prosthesis. We examined the associations between oral health status in 2013 and 35 health and well-being outcomes in 2019, including physical/cognitive health, psychological distress, subjective health, social well-being, prosocial/altruistic behaviors, and health behaviors, using two databases (n=32,827 and 15,905). RESULTS: Compared to individuals with ≥20 teeth, those with <20 teeth had a 10-33% higher risk of mortality and a 7-10% higher risk of functional disability six years later. Additionally, individuals with fewer than 20 teeth tended to go out less frequently and eat fewer vegetables and fruits. Furthermore, individuals with 0-9 teeth without a prosthesis were more likely to have severe functional disability (risk ratio (RR):1.17, 95% confidence interval (CI):1.05-1.31), engage in fewer intellectual activities (standardized difference: 0.17, 95% CI: 0.10-0.24), and feel more hopeless (RR: 1.21, 95% CI: 1.04-1.41). CONCLUSIONS: The prevention of tooth loss and prosthodontic treatment may be associated with reduced mortality and functional disability, as well as maintenance of intellectual ability, frequency of going out, and improvements in dietary lifestyle.

Dental prosthesis use is associated with higher protein intake among older adults with tooth loss.

BACKGROUND: Tooth loss is associated with reduced protein intake, which leads to sarcopenia and frailty in older adults. OBJECTIVE: To evaluate the protective effect of dental prostheses on decreased protein intake in older adults with tooth loss. METHODS: This cross-sectional study was based on a self-reported questionnaire targeting older adults. Data were obtained from the Iwanuma Survey of the Japan Gerontological Evaluation Study. We used % energy intake (%E) of total protein as the outcome and the use of dental prostheses and number of remaining teeth as explanatory variables. We estimated the controlled direct effects of tooth loss by fixing the use/non-use of dental prostheses based on a causal mediation analysis, including possible confounders. RESULTS: Among 2095 participants, the mean age was 81.1 years (1SD = 5.1), and 43.9% were men. The average protein intake was 17.4%E (1SD = 3.4) of the total energy intake. Among participants with ≥20, 10-19 and 0-9 remaining teeth, the average protein intake was 17.7%E, 17.2%E/17.4%E and 17.0%E/15.4%E (with/without a dental prosthesis), respectively. Compared to participants with ≥20 remaining teeth, those with 10-19 remaining teeth without a dental prosthesis did not have a significantly different total protein intake (p > .05). Among those with 0-9 remaining teeth without a dental prosthesis, total protein intake was significantly low (-2.31%, p < .001); however, the use of dental prostheses mitigated the association by 79.4% (p < .001). CONCLUSION: Our results suggest that prosthodontic treatment could contribute to maintaining protein intake in older adults with severe tooth loss.

Effectiveness of COVID-19 vaccines against infection in Japan: A test-negative study from the VENUS study.

BACKGROUND: Although the effectiveness of coronavirus disease 2019 (COVID-19) vaccines is a crucial public health concern, evidence from Western Pacific countries is limited, including Japan. This study aimed to estimate the COVID-19 vaccines effectiveness (VE) against infection during the Delta variant predominance (July-September 2021) in Japan. METHODS: We performed a test-negative study using COVID-19 test data of ≥20-year-old residents in four municipalities who were tested in medical institutions between July 1 and September 30, 2021. We extracted COVID-19 test data from healthcare claims data, and the vaccination status at the testing date was ascertained using the Vaccination Record System data. Confirmed positive cases were identified using data from the national system for COVID-19, Health Center Real-time Information-sharing System on COVID-19. Logistic regression analyses were conducted to estimate the odds of testing positive according to vaccination status. VE was calculated as (1 - odds ratio) × 100%. RESULTS: This study included 530 positive and 15,650 negative results. Adjusted manufacturer-unspecified VE was 4.1% (95% confidence interval [CI], -36.5-32.6) at 0-13 days after the first dose, 45.2% (95% CI, 13.4-65.3) at ≥14 days after the first dose, 85.2% (95% CI, 69.9-92.7) at 0-13 days after the second dose, and 79.6% (95% CI, 72.6-84.8) at ≥14 days after the second dose. In addition, the VE after the second dose was highest at 14-34 days after the dose (VE, 89.1%; 95% CI, 80.5-93.9). CONCLUSIONS: High real-world effectiveness of COVID-19 vaccines, especially two doses, against infection during the Delta variant predominance in Japan was confirmed.

Compliance Trajectory and Patterns of COVID-19 Preventive Measures, Japan, 2020-2022.

COVID-19 remains a global health threat. Compliance with nonpharmaceutical interventions is essential because of limited effectiveness of COVID-19 vaccines, emergence of highly contagious variants, and declining COVID-19 antibody titers over time. We evaluated compliance with 14 nonpharmaceutical intervention-related COVID-19 preventive behaviors, including mask wearing, ventilation, and surface sanitation, in a longitudinal study in Japan using 4 waves of Internet survey data obtained during 2020-2022. Compliance with most preventive behaviors increased or remained stable during the 2-year period, except for surface sanitation and going out behaviors; compliance with ventilation behavior substantially decreased in winter. Compliance patterns identified from latent class analysis showed that the number of persons in the low compliance class decreased, whereas those in the personal hygiene class increased. Our findings reflect the relaxation of mobility restriction policy in Japan, where the COVID-19 pandemic continues. Policymakers should consider behavioral changes caused by new policies to improve COVID-19 prevention strategies.

Lower socio-economic status in adolescence is associated with poor oral health at an older age: Mediation by social and behavioural factors.

AIM: To examine the mediators between lower socio-economic status (SES) in adolescence and oral health at an older age to uncover the underlying mechanisms of the association. METHODS: Participants (n = 21 536) aged ≥65 years from the Japan Gerontological Evaluation Study were evaluated. The dependent variables were self-rated chewing difficulty and having ≤19 remaining teeth. The main independent variable was self-perceived SES in adolescence. The Karlson-Holm-Breen method was used for mediation analysis. RESULTS: Mean age of the participants was 74.8 years (standard deviation = 6.4), and 51.5% were female. Overall, 5598 (26.0%) participants reported chewing difficulty and 9404 (43.7%) had ≤19 remaining teeth. Lower SES in adolescence was associated with a higher prevalence of chewing difficulty (odds ratio [OR] = 1.38, 95%confidence interval [CI] = 1.29-1.48; total effect). After controlling for mediators, OR for lower SES in adolescence was 1.22 (95%CI = 1.13-1.30; direct effect) and 1.13 (95%CI = 1.11-1.16; indirect effect). Mediators, prominently the number of teeth and income, explained 39.3% of the associations. Lower SES in adolescence increased the odds of ≤19 remaining teeth by OR = 1.23 (95% CI = 1.16-1.31; total effect). After controlling for mediators, the OR for lower SES in adolescence was 1.03 (95%CI = 0.97-1.10; direct effect) and 1.19 (95%CI = 1.16-1.23; indirect effect). Mediators, prominently educational attainment, explained 85.0% of the associations. CONCLUSIONS: Lower SES in adolescence was associated with poor oral health at an older age through mediators. Approaches that consider social determinants from the beginning of the life course are required.

Oral status and incident functional disability: A 9-year prospective cohort study from the JAGES.

INTRODUCTION: The population-attributable risk of oral status for incident functional disability remains unknown. We investigated the impact of a range of oral statuses (number of remaining teeth, chewing difficulty, dry mouth, and choking) on incident functional disability. METHODS: Participants (n = 44,083) aged ≥ 65 years from the Japan Gerontological Evaluation Study were evaluated. The outcome variable was incident functional disability, and the explanatory variables were four select oral statuses. The possible confounders were included as covariates. Using the Cox proportional hazards model, we calculated hazard ratios (HRs), 95% confidence intervals (CIs), and their population-attributable fractions (PAFs). RESULTS: The mean age of the participants was 73.7 (standard deviation=6.0) years at baseline, and 53.2% were women. A total of 8,091 participants (18.4%) developed functional disabilities during the follow-up period. Among the four oral statuses, the incidence rate of functional disability was the highest in those with chewing difficulty (3.27/100 person-years), followed by those with dry mouth (3.20/100 person-years), choking (3.10/100 person-years), and ≤19 remaining teeth (2.89/100 person-years). After adjusting for all covariates, chewing difficulty showed the highest risk of functional disability (HR=1.22, 95%CI=1.16-1.28), followed by ≤19 remaining teeth (HR=1.18, 95%CI=1.12-1.25), dry mouth (HR=1.18, 95%CI=1.12-1.24), and choking (HR=1.10, 95%CI=1.04-1.17). Regarding PAF, ≤19 remaining teeth (12.0%) were the largest, followed by chewing difficulty (7.2%), dry mouth (4.6%), and choking (1.9%). CONCLUSIONS: Maintaining a good oral status may reduce the risk of functional disability later in life. Given its population contribution, tooth loss had the largest impact among the four oral conditions.

Co-Payments and Inequality in Gingival Bleeding and Dental Visits.

OBJECTIVES: Japan's universal health insurance covers a wide range of dental treatments, and the co-payment rates differ by age. We investigated whether the inequality in gingival bleeding and dental visits was smaller amongst those with lower co-payment rates. METHODS: This cross-sectional study used data from the 2019 Japan Gerontological Evaluation Study. The participants were functionally independent adults aged 65 years or older. The dependent variables were current gingival bleeding as a symptom of periodontal diseases and dental nonattendance for treatment in the past year. The independent variables were ridit scores of equivalent income and educational status. For covariates, we used age, sex, and the number of remaining teeth. To evaluate the inequalities, we used the slope index of inequality (SII) and the relative index of inequality (RII). We also conducted stratified analyses by co-payment rates (30%, 20%, and 10%) to clarify the difference in inequalities by co-payment rate. RESULTS: A total of 15,389 participants were included in the analysis; their mean age was 71.8 (SD = 4.1) and 51.8% were women. There were significant absolute and relative inequalities in gingival bleeding and dental visits by equivalent income and education. With regards to educational status, inequalities were lower with a decrease in the co-payment rate. In particular, relative inequality by education in gingival bleeding was the largest amongst the 30% co-payment group (RII, 1.918; 95% confidence interval [CI], 1.386 to 2.656). For gingival bleeding, the absolute and relative inequality by equivalent income were not significant amongst the 10% co-payment group (SII, -0.003; 95% CI, -0.003 to 0.028; RII, 1.006; 95% CI = 0.676 to 1.498). CONCLUSIONS: A low co-payment rate was associated with smaller inequalities in gingival bleeding and dental visits by equivalent income and educational status.