高齢者における所得格差と残存歯数の関連:JAGES2013新潟市データ  [in Japanese] Association between income inequality and dental status in Japanese older adults: Analysis of data from JAGES2013  [in Japanese]

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Author(s)

    • 相田 潤 AIDA Jun
    • 東北大学大学院歯学研究科国際歯科保健学分野 Department of International and Community Oral Health, Tohoku University Graduate School of Dentistry
    • 菖蒲川 由郷 SHOBUGAWA Yugo
    • 新潟大学大学院医歯学総合研究科国際保健学分野 Division of International Health, Niigata University Graduate School of Medical and Dental Sciences
    • 山本 龍生 YAMAMOTO Tatsuo
    • 神奈川歯科大学大学院歯学研究科口腔科学講座(社会歯科学分野) Department of Oral Science, Kanagawa Dental University Graduate School of Dentistry
    • 齋藤 玲子 SAITO Reiko
    • 新潟大学大学院医歯学総合研究科国際保健学分野 Division of International Health, Niigata University Graduate School of Medical and Dental Sciences
    • 近藤 克則 KONDO Katsunori
    • 千葉大学予防医学センター社会予防医学研究部門,国立長寿医療研究センター老年学評価研究部 Center for Preventive Medical Sciences, Chiba University, Center for Gerontology and Social Science, National Center for Geriatrics and Gerontology

Abstract

<p><b>目的</b> 高齢者における残存歯の実態と背景にある要因を明らかにすることを目的として,個人の所得や暮らしのゆとりといった経済的な状況で説明されるかどうか,それらを考慮しても高齢者の残存歯数がジニ係数により評価した居住地の所得の不平等と関連するか検討した。</p><p><b>方法</b> 介護認定を受けていない65歳以上の高齢者を対象として2013年に全国で約20万人を対象に行われた健康と暮らしの調査(JAGES2013,回収率71.1%)において,新潟市データを分析対象とした。自記式調査票を用いて新潟市に住民票がある8,000人に郵送調査を実施し,4,983人(62.3%)より回答を得て,年齢と性別に欠損が無かった3,980人(49.8%)の有効回答を使用した。中学校区別の所得格差(ジニ係数)と残存歯数の地域相関を求め,ジニ係数別の残存歯数を比較した。次に,目的変数を残存歯数,説明変数を個人レベルの変数として,性別,年齢以外に,教育歴,等価所得,暮らしのゆとり,世帯人数,糖尿病治療の有無,喫煙状況を用い,地域レベルの変数として,中学校区ごとの平均等価所得とジニ係数とした順序ロジスティック回帰モデルによるマルチレベル分析を行った。</p><p><b>結果</b> 57中学校区別のジニ係数と残存歯数の地域相関は,相関係数−0.44(<i>P</i><0.01)の弱い負の相関を認め,ジニ係数が0.35以上の所得格差が大きい地域は他の地域と比較して有意(<i>P</i><0.001)に残存歯数が少なかった。残存歯数を目的変数とした順序ロジスティック回帰モデルにおいて,性別と年齢を調整後,個人レベルでは教育歴,等価所得,暮らしのゆとり,喫煙状況,地域レベルではジニ係数,平均等価所得が有意な変数であった。一方で,すべての変数を投入したモデルでは,個人レベルの教育歴と地域レベルの平均等価所得において有意な結果は得られなかった。</p><p><b>結論</b> 所得格差が比較的小さいと考えられる日本の地方都市においても,個人レベルの要因を調整後に地域レベルの所得格差と残存歯数の間に関連が認められた。高齢者の残存歯数は永久歯への生え変わり以降,長い時間をかけて形成されたものであり,機序は明らかではないが,所得分配の不平等が住民の健康状態を決めるとする相対所得仮説は,今回対象となった高齢者の残存歯数において支持される結果であった。</p>

<p><b>Objectives</b> Personal income affects dental status in older people. However, the impact of income inequality on dental status at the community level (junior high school district) is unclear. The purpose of this study was to examine the association between dental status and community level income inequity after adjust for individual socio-economic status in Japanese older adults, and to verify the relative income hypothesis, also known as the Wilkinson hypothesis.</p><p><b>Methods</b> We used data from the Japan Gerontological Evaluation Study (JAGES) conducted in Niigata city. JAGES is a postal survey of functionally independent adults aged 65 years or older. We enrolled 4,983 respondents (response rate 62.3%) and used data on 3,980 of them after excluding incomplete data. We evaluated health condition and socio-economic status using questionnaires. The Gini coefficient, as an indicator of income inequality, was calculated by junior high school district (57 districts) based on the data from the questionnaire. Additionally, the Pearson's coefficient of correlation was calculated to evaluate the association between the mean number of remaining teeth and the community level Gini coefficient. Then we evaluated the mean number of remaining teeth among the groups stratified by the Gini coefficient conditions. Next, we conducted a multilevel analysis using an ordinal logistic regression model. The number of remaining teeth was set as the dependent variable, while sex, age, household size, education, smoking status, diabetes treatment, current living conditions, and equivalent income were used as independent variables at the individual level. The Gini coefficient and average equivalent income in the junior high school district were used as independent variables at the community level.</p><p><b>Results</b> The Pearson's correlation coefficient for the relationship between the Gini coefficient and the mean number of remaining teeth in the junior high school district was −0.44 (<i>P</i><0.01). Wider income disparity area (Gini coefficient≧0.35) revealed a significantly small number of remaining teeth (<i>P</i><0.001). The multilevel analysis showed that a higher Gini coefficient and a lower average equivalent income at the community level were significantly associated with a lower number of remaining teeth, and with educational attainment, smoking status, current living conditions, and equivalent income at the individual level, after adjusting for sex and age. On the other hand, educational attainment at the individual level, and average equivalent income at the community level were not significant factors after adjusting for all individual level variables.</p><p><b>Conclusion</b> This study showed that, in addition to individual socio-economic status, income inequality at the community level was significantly associated with number of remaining teeth in Japanese older adults. Although the precise mechanism of this association is still unclear, our result supports the relative income hypothesis.</p>

Journal

  • Nihon Koshu Eisei Zasshi(JAPANESE JOURNAL OF PUBLIC HEALTH)

    Nihon Koshu Eisei Zasshi(JAPANESE JOURNAL OF PUBLIC HEALTH) 64(4), 190-196, 2017

    Japanese Society of Public Health

Codes

  • NII Article ID (NAID)
    130005634041
  • NII NACSIS-CAT ID (NCID)
    AN00189323
  • Text Lang
    JPN
  • ISSN
    0546-1766
  • NDL Article ID
    028132469
  • NDL Call No.
    Z19-216
  • Data Source
    NDL  J-STAGE 
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