Department of International and Community Oral Health, Tohoku University Graduate School of Dentistry, Sendai, Japan.
Department of Oral Health Promotion, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Bunkyo-ku, Japan.
Community Dent Oral Epidemiol. 2023 Jun;51(3):557-564. doi: 10.1111/cdoe.12749. Epub 2022 May 15.
Studies suggest that wearing dentures to restore missing teeth can have a positive impact on health status. However, income inequalities in denture wearing exist. The aim of this study was to investigate how differing co-payment rates under the current Japanese Universal Health Insurance Coverage System affect income inequalities in denture non-use among older adults with severe tooth loss.
This cross-sectional study used data from the 2019 Japan Gerontological Evaluation Study (JAGES). Self-administered questionnaires were mailed to 345 356 independent people who did not receive long-term care insurance benefits and were aged ≥65 years. The dependent variable was denture non-use, and the independent variable was the equivalent annual household income. The Slope Index of Inequality (SII) and Relative Index of Inequality (RII) were used with regression-based approaches to determine both absolute and relative inequalities in denture non-use by co-payment rates. The covariates were sex, age, years of education, number of teeth and comorbidities.
Of the 240 889 responses received (response rate =69.9%), we analysed 21 594 participants who fulfilled the inclusion criteria. The mean age was 72.8 years (standard deviation =4.1), and 57.6% were men. For 30 per cent, 20 per cent and 10 per cent co-payment rates, the percentages of people who did not use dentures and had severe tooth loss (≤9 teeth) were 18.3%, 13.3%, and 8.5%, respectively. All analyses confirmed significant inequalities in denture non-use. The lower the co-payment rate, the smaller the inequalities. SIIs for each co-payment rate were as follows: 30 per cent =13.35% (95% confidence interval [CI] = 9.61-17.09); 20 per cent =7.85% (95% CI = 4.88-10.81); and 10 per cent =4.85% (95% CI = 2.55-7.16). Inclusion of interaction term between income and co-payment rate significantly lowered the inequalities by co-payment rate in logistic regression analysis and SII. For RII, although the interaction was not statistically significant, a similar trend was observed.
Income inequalities in denture use existed among older adults with severe tooth loss in Japan, and the inequalities appeared to be greater when the co-payment rate was higher.
研究表明，佩戴义齿修复缺失的牙齿可以对健康状况产生积极影响。然而，在佩戴义齿方面存在收入不平等现象。本研究旨在调查在现行日本全民健康保险覆盖制度下，不同共付率如何影响严重缺牙的老年人中不使用义齿的收入不平等。
本横断面研究使用了 2019 年日本老年评估研究（JAGES）的数据。向 345356 名未享受长期护理保险福利且年龄≥65 岁的独立人群邮寄了自我管理问卷。因变量为不使用义齿，自变量为等效家庭年收入。使用基于回归的方法，采用不平等斜率指数（SII）和相对不平等指数（RII）来确定不同共付率下义齿不使用率的绝对和相对不平等。协变量为性别、年龄、受教育年限、牙齿数量和合并症。
在收到的 240889 份回复中（回复率为 69.9%），我们分析了符合纳入标准的 21594 名参与者。平均年龄为 72.8 岁（标准差为 4.1），其中 57.6%为男性。对于 30%、20%和 10%的共付率，不使用义齿且严重缺牙（≤9 颗）的人数百分比分别为 18.3%、13.3%和 8.5%。所有分析均证实了义齿不使用率存在显著的不平等现象。共付率越低，不平等程度越小。每个共付率的 SII 如下：30%=13.35%（95%置信区间[CI]：9.61-17.09）；20%=7.85%（95%CI：4.88-10.81）；10%=4.85%（95%CI：2.55-7.16）。在逻辑回归分析和 SII 中，包含收入和共付率之间的交互项显著降低了共付率的不平等。对于 RII，尽管交互项没有统计学意义，但观察到了类似的趋势。
在日本严重缺牙的老年人中，使用义齿存在收入不平等现象，而且当共付率较高时，不平等现象似乎更为严重。
