Body Mass Index and Waist Circumference as Predictors of Disability in Nonagenarians: The Vitality 90+ Study.

Background: Only scarce data exist on the association between obesity and disability in the oldest old. The purpose of this prospective study is to examine if body mass index and waist circumference (WC) are associated with incident mobility and activities of daily living (ADL) disability in nonagenarians.

Methods: We used longitudinal data from the Vitality 90+ Study, which is a population-based study conducted at the area of Tampere, Finland. Altogether 291 women and 134 men, aged 90-91 years, had measured data on body mass index and/or WC and did not have self-reported mobility or ADL disability at baseline. Incident mobility and ADL disability was followed-up on median 3.6 years (range 0.6-7.8 years). Mortality was also followed-up. Multinomial logistic regression models were used for the analyses, as death was treated as an alternative outcome. The follow-up time was taken into account in the analyses.

Results: Neither low or high body mass index, nor low or high WC, were associated with incident mobility disability. In women, the lowest WC tertile (<82 cm) was associated with an increased probability of incident ADL disability when compared to the middle WC tertile (odds ratio 3.98, 95% CI 1.35-11.77).

Conclusions: Obesity is not associated with incident mobility or ADL disability in nonagenarians. Instead, low WC is associated with an increased risk of developing ADL disability in nonagenarian women.