Association between dental status and incident disability in an older Japanese population

Objectives To determine the association between dental health status and onset of functional disability in older Japanese people. Design Prospective cohort study. Setting Six Japanese municipalities. Participants Four thousand four hundred twenty-five community-dwelling individuals aged 65 and over. Measurements The outcome measure was the onset of functional disability based on public records of people receiving long-term care insurance benefits, determined through a standardized multistep assessment of functional and cognitive impairment including a personal interview and an examination by a physician. Disability data were analyzed for 4,425 respondents during 2003 to 2007. Self-reported number of remaining teeth and eating ability were used as measures of dental health status. Age, sex, body mass index, self-rated health, present illness, smoking, alcohol, exercise, and equivalent income were used as covariates. Results In the age- and sex-adjusted Cox proportional hazard models, there were significant associations between number of remaining teeth, eating ability, and onset of disability. After adjusting for sociodemographic, behavioral, and health status variables, respondents with 19 or fewer teeth had a significant 1.21 (95% confidence interval = 1.06-1.40) times higher hazard ratio for the onset of functional disability. In contrast, eating ability was not significantly associated with the onset of disability. Conclusion Poor dental status was associated with a higher risk of onset of functional disability in older Japanese people. Sociodemographic, behavioral, and health status covariates explained the association between eating ability and onset of disability.