Predictors and correlates of edentulism in the healthy old people in Edinburgh (HOPE) study

To determine the extent to which correlates of edentulism are explained by an association between tooth loss and cognitive ability.

Participants in the Healthy Old People in Edinburgh (HOPE) study aged 70 or more at baseline were assessed and health, cognitive, socio-economic and socio-environmental data collected on four consecutive occasions. It was noted whether the participant had any retained teeth and if not, the age when the last tooth was lost. Prior determinants of edentulism were investigated with binary logistic regression models. At the 9-year follow-up, associations with edentulism were examined using general linear models with edentulism as an independent factor.

201 participants were adequately tested, of whom 104 (51.7%) were edentulous. A logistic regression model that considered age, sex, education, social class, deprivation index of residence, objective distance from dentist, participant's estimate of distance from dentist and NART-estimated IQ (NARTIQ) found age (p = 0.032), occupational class (p = 0.019) and NARTIQ (p = 0.027) as significant predictors of edentulism. Cox's proportional hazards modelling found only NARTIQ (p = 0.050) to be correlated. Being edentulous was associated with poorer respiratory function but not hand grip strength (p = 0.23). Edentulous participants had lower self esteem scores (p = 0.020) and poorer dietary assessment scores (p = 0.028). Being edentulous was also associated with significantly lower mean scores on all cognitive testing, although these associations became non-significant after adjustment for NARTIQ and age.

In healthy older people, edentulism is associated with relative impairment of cognitive ability, although this association is explained by the fact that lower original intelligence predisposes to edentulism and poorer performance on cognitive tests in old age. Once original intelligence is adjusted for, tooth loss is not related to cognitive ability. Tooth loss is, however, associated with poorer status across a wide range of health measures: physical health, nutrition, disability and self-esteem. Establishing the degree to which these health outcomes are causally related to edentulism could usefully be factored into cost-benefit analyses of programmes designed to prevent tooth loss.