Disability in the Oldest-Old: Incidence and Risk Factors in The 90+ Study

Objectives: To measure the incidence of disability in individuals aged 90 years and older and examine factors that may increase risk of disability. Design and Setting: The 90+ Study, a longitudinal study of aging, initiated in January 2003 with follow-up through May 2009. Participants: A total of 216 nondisabled, prospectively followed participants who were aged 90 years or older at baseline. Measurements: The incidence of disability was measured as needing help on one or more activities of daily living and calculated using person years. Risk factors were examined by using a Cox proportional hazards analysis. Results: The overall incidence of disability was 164% per year (95% confidence interval: 13.3-20.0) and did not differ by gender. Disability incidence increased with age from 8.3% in the 90-94 age group to 25.7% in the 95 years and older age group. Several factors were associated with increased risk of disability, including history of congestive heart failure, depression, poor self-rated quality of life, and cognitive impairment. Conclusion: Disability incidence is high and increases rapidly with age in the oldest-old, with rates essentially tripling between ages 90-94 years and 95+ years. Some factors associated with increased risk of disability in younger elderly continue to be risk factors in the oldest-old. Because of the tremendous social and financial impact of disability and the rapid growth of the oldest-old, the development of strategies to delay disability in the elderly should be a priority for healthcare research. (Am J Geriatr Psychiatry 2012; 20:159-168)