The prevalence of disability in the oldest-old is high and continues to increase with age: findings from The 90+ Study

Abstract

Objectives: To examine the prevalence and type of disability in the oldest-old (90+), the fastest growing age group in the United States.

Methods: The current study included functional data on 697 participants from The 90+ Study, a population-based longitudinal study of aging and dementia in people aged 90 and older. Data were obtained by participant's informants via a written questionnaire. The prevalence of disability was calculated for two definitions using activities of daily living (ADLs). ADL difficulty was defined as difficulty with one or more ADLs whereas ADL dependency was defined as needing help on one or more ADLs.

Results: ADL difficulty was present in 71% in 90-94 year olds, 89% in 95-99 year olds, and 97% in centenarians. ADL dependency was present in 44% of 90-94 year olds, 66% of 95-99 year olds, and 92% of centenarians. The ADL most commonly causing difficulty was walking (70%) whereas the ADL most commonly causing dependency was bathing (51%). Age, gender, and institutionalization were significantly associated with both ADL difficulty and ADL dependency.

Conclusions: Similar to studies in younger individuals, the current study suggests that the prevalence of disability continues to increase rapidly in people aged 90 and older. With the rapid growth in the number of people in this age group, disability in the oldest-old has major public health implications.