Disability in the individual ADL, IADL, and mobility among older adults: A prospective cohort study

Objectives: To examine the risk of disability in 15 individual ADL, IADL, and mobility in older adults by age; and to assess the association of multimorbidity, gender, and education with disability. Design & Setting: A prospective cohort study. The sample included 805 community-dwelling older people aged 60+ living in the Netherlands. Measurements: Disability was assessed using the Katz-15 Index of Independence in Basic Activities of Daily Living (ADL), Instrumental Activities of Daily Living (IADL) and one mobility item. Disability in any of these activities was defined as the inability to perform the activity without assistance. The risk of disability by age for each individual ADL, IADL, and for mobility was assessed using Generalized mixed models. Results: Disability in activities as household tasks, traveling, shopping, and continence had the highest risk and increased rapidly with age. The risk traveling disability among people aged 65 with two comorbidities increase from 9% to 37% at age 85. Disability in using the telephone, managing medications, finances, transferring, and toileting, had a very low risk and hardly increased with age. Compared to those without chronic conditions, those with ≥ 3 chronic conditions had a 3 to 5 times higher risk of developing disability. Males had a higher risk of disability in managing medication (P=0.005), and preparing meals (P=0.019), whereas females had a higher risk of disability with traveling (P=0.001). No association between education and disability on the individual ADL, IADL, and mobility was observed. Conclusions: Older adults were mostly disabled in physical related activities, whereas disability in more cognitive related activities was less often experienced. The impact of multimorbidity on disability in each activity was substantial, while education was not.