Disability trends among nonagenarians in 2001–2007: Vitality 90+ Study

Substantial growth of the population aged 90 years or over has focused interest on trends in the functioning and disability
of the oldest old, but research findings are scarce and they vary. In the Vitality 90+ Study, we evaluated overall, gender-specific,
and age-specific trends in disability among total cohorts of people aged 90 years or older in the city of Tampere, Finland,
in the years 2001, 2003, and 2007. The size of the target population ranged from 1113 to 1146 and the participation rate from
79 to 86%. The participants were asked whether they were able to get in and out of bed, dress and undress, move about indoors,
walk 400 m, and use stairs. Independence was defined as being able to perform an activity without help. The aggregate outcome
measures included independence in all five activities, dependence in one to four activities, dependence in all five activities
(severe dependence), and a disability score. In analyses taking into account the within subject associations which resulted
due to those who participated in several years, and proxy respondents, no overall or gender-specific trend was found in any
of the independence or dependence estimates. In each year, independence decreased clearly by increasing age. Our results imply
stable disability levels in nonagenarians in a population with increasing life expectancy and improving survival until the
age of 90. Longer-time series are needed to confirm the trends.