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 16.4% 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.