Use of the dental formula from the National Database of Health Insurance Claims and Specific Health Checkups of Japan

Association among the number of natural teeth, dental maintenance visits and diabetes status: a cross-sectional study using employment-based healthcare claims database

Aim

Although diabetes is associated with the risk of tooth loss, there are no large-scale studies examining the reality and the effectiveness of dental maintenance visits in preventing tooth loss. We aimed to investigate the associations among the number of teeth, dental maintenance visits and diabetic status.

Methods

This is a cross-sectional study: a database comprising employment-based health insurance claim and medical check-up data between April 2015 and March 2016. From the dental receipts for a total of 705,542 individuals aged 20-74 years, we calculated dental visits ratio. After excluding missing data on the number of teeth and HbA1c, the association between dental maintenance visits and the number of teeth was further examined in 185,820 individuals aged 40-69 years visited a dentist by diabetes status.

Results

The percentage of dental visits was 46% overall, particularly low among younger subjects (34% in 20 s, 43% in 30 s), and increased with age. The maintenance-included group had a higher number of teeth than the treatment-only group, even at older ages, and this association was observed regardless of diabetes or glycemic control status. Furthermore, even with diabetes, the number of teeth in the group with good glycemic control was like that of non-diabetic.

Conclusion

Dental visits ratio was particularly low among younger subjects and those who receive dental maintenance had a higher number of teeth, regardless of diabetes or not. Adequate glycemic control and dental maintenance were associated with the number of teeth in the people with diabetes. The results suggest that it is important for physicians to work closely with dentists to promote patient-centered care and encourage both maintenance visits and better glycemic control.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13340-025-00805-1.

Time-study research on maxillofacial prosthetic treatment

Unreasonable medical fees can cause problems such as increased medical costs, greater medical disparities, decreased medical standards, and physician shortages. To prevent such problems, it is important to set appropriate medical fees, ensure their proper use, and improve the efficiency of medical care. The treatment of patients with maxillofacial defects is generally more expensive compared with general prosthodontic treatment because it involves more materials and requires more frequently follow-ups for longer period. However, the actual time required for maxillofacial prosthetic treatment is unclear. Therefore, in this study, we aimed to clarify the amount of time spent treating maxillofacial prosthetic patients. We analyzed clinical data from patients undergoing routine maxillofacial prosthetic treatment, irrespective of difficulty level, at 8 university hospitals and 2 dental clinics. We also collected data from maxillofacial prosthodontists on the treatment time required for various Japanese health insurance items, including the fabrication of maxillofacial prostheses. The results revealed that some aspects of maxillofacial prosthetic treatment may take longer to perform and are more costly to perform than previously thought, suggesting the need for some adjustments to the health insurance reimbursement system. Maintaining an appropriate balance between expenditures and fees will greatly benefit patients and physicians, ensuring positive health outcomes and a healthy society.

Effect of oral health on functional disability and mortality in older adults in Japan: a cohort study

BACKGROUND

Oral health has previously shown associations with functional disability and mortality. We aimed to explore the associations of various aspects of oral health status with functional disability and mortality using survival analysis, as well as the relative magnitudes of the impact of these aspects on outcomes.

METHODS

We obtained data for individuals aged 75 years and older in Shimane, Japan, who had at least one oral health check-up between April 1, 2016, and March 31, 2022 under Japan's long-life medical care system insurance system. Those with missing data or with functional disability at baseline were excluded. 13 aspects of oral health status were assessed by dentists or dental hygienists as part of the check-up (using protocols provided by the Japan Dental Association and the Japanese Ministry of Health, Labour and Welfare): number of remaining teeth, subjective masticatory performance, objective masticatory performance, periodontal tissue status, functional dysphagia, tongue mobility, articulation, oral hygiene, number of decayed teeth, inadaptation of dentures of the upper jaw and lower jaw (considered separately), oral mucosal disease, and dry mouth. Multivariate Cox proportional hazards models were used to analyse the associations between each aspect of oral health and functional disability and mortality, with fully adjusted models adjusting for sex, age, BMI, medical history, or a propensity score derived from these covariates. Population-attributable fractions (PAFs) were calculated to assess the differential impacts of these oral health status aspects on outcome occurrence.

FINDINGS

Of the 24 619 individuals who had an oral health check-up during the study period, 21 881 individuals were included in the analysis of functional disability (9175 [41·93%] men, 12 706 [58·07%] women, mean age 78·31 years [SD 2·88], mean follow-up 41·43 months [20·80]), and 22 747 individuals in the analysis of mortality (9722 [42·74%] men, 13 025 [57·26%] women, mean age 78·34 years [2·89], mean follow-up 42·63 months [20·58]). All 13 aspects of oral health status showed significant associations with the occurrence of mortality, while functional disability was associated with 11 aspects (excluding oral mucosal disease and dry mouth) in the fully adjusted model. Based on PAFs, of all oral health aspects assessed, objective masticatory performance had the greatest impact on both functional disability (PAF 23·10% [95% CI 20·42-25·69] for the lowest and 10·62% [8·18-12·99] for the second-lowest quartile of performance) and mortality (16·47% [13·44-19·40] and 8·90% [5·87-11·82]).

INTERPRETATION

Various aspects of oral health are associated with mortality and functional disability. Maintaining good oral health in older adults might help to reduce these outcomes.

FUNDING

None.

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.

Association between the number of teeth and incident pre-diabetes among middle-aged adults with periodontal disease: a retrospective cohort analysis of Japanese claims data

OBJECTIVES

To investigate the association between the number of teeth and the new onset of pre-diabetes.

DESIGN

Retrospective cohort study.

SETTING

The National Database of Health Insurance Claims and Specific Health Checkups of Japan, which holds information from both the yearly health check-up programme known as the 'Specific Health Checkup' and health insurance claims data.

PARTICIPANTS

1 098 371 normoglycaemic subjects who participated in the Specific Health Checkup programme every year from fiscal year (FY) 2015 to FY 2018 and had dental insurance claims data with a diagnosis of periodontal disease during FY 2016.

OUTCOME MEASURES

Incidence of pre-diabetes or diabetes observed at the Specific Health Checkup during FY 2018.

RESULTS

Among the participants, 1 77 908 subjects developed pre-diabetes, and 579 developed diabetes at the check-up during the subsequent follow-up year. Compared with the subjects with 26-28 teeth, those with 20-25, 15-19 or 1-14 teeth were associated with an increased likelihood of developing pre-diabetes or diabetes onset with adjusted ORs of 1.03 (95% CI: 1.02 to 1.05), 1.06 (1.03 to 1.09) and 1.07 (1.04 to 1.11), respectively. No clear modifications were observed for age, sex, body mass index or current smoking.

CONCLUSIONS

Having fewer teeth was associated with a higher incidence of pre-diabetes. Due to the limitations of this study, however, causality remains undetermined.

Validation studies of Japanese administrative health care data: A scoping review

PURPOSE

Large-scale administrative health care databases are increasingly being utilized for research. However, there has not been much literature that validated administrative data in Japan; a previous review identified six validation studies published between 2011 and 2017. We conducted a literature review of studies that assessed the validity of Japanese administrative health care data.

METHODS

We searched for studies published by March 2022 that compared individual-level administrative data with a reference standard from another data source, as well as studies that validated administrative data using other data within the same database. The eligible studies were also summarized based on characteristics which included data types, settings, reference standard used, numbers of patients, and conditions validated.

RESULTS

There were 36 eligible studies, including 29 that used external reference standard and seven that validated administrative data using other data within the same database. Chart review was the reference standard in 21 studies (range of the numbers of patients, 72-1674; 11 studies conducted in single institutions and nine studies in 2-5 institutions). Five studies used a disease registry as the reference standard. Diagnoses of cardiovascular diseases, cancer, and diabetes were frequently evaluated.

CONCLUSIONS

Validation studies are being conducted at an increasing rate in Japan, although most of them are small scale. Further large-scale comprehensive validation studies are necessary to effectively utilize the databases for research.

Current Medical Technology Reimbursement System in Japan

OBJECTIVES

The process for reimbursement of medical technologies in Japan is complex, and to date, it has not been well described overall. This article aims to provide an overview of the reimbursement system for medical technologies in Japan, including the reimbursement application process and the payment decision making.

METHODS

Conduct review for relevant health policy and regulation and gather opinion from the key stakeholders.

RESULTS

The Japanese functional category listing system for the reimbursement of medical technologies is a unique fee-for-service payment system, and the timing for the listing is dependent on the application category. A key positive aspect of the current system is the level of transparency and the predictable pathway for reimbursement of new medical technologies. Conversely, the current reimbursement process may not capture the true extent of the innovation of new technologies, especially when creating a new functional category and/or a new medical procedure coding.

CONCLUSIONS

There are potential areas where changes could improve access, efficiencies, and value, such as the price revision system based on the market survey, the foreign average price assessment, and the health technology assessment system. These additions and modifications in policy and regulation of reimbursement will help facilitate the effective and efficient access to new innovative medical technologies within the context of a sustainable and affordable National Health Insurance system in Japan.