To determine the test–retest reliability and criterion validity of self-reported function in mobility and instrumental activities of daily living (IADL) in older adults, a convenience sample of 70 subjects (72.9 ± 6.6 yr, 34 male) was split into able and disabled groups based on baseline assessment and into consistently able, consistently disabled, and inconsistent based on repeat assessments over 2 weeks. The criterion validities of the self-reported measures of mobility domain and IADL-physical subdomain were assessed with concurrent baseline measures of 4 mobility performances, and that of the self-reported measure of IADL-cognitive subdomain, with the Mini-Mental State Examination. Test–retest reliability was moderate for the mobility, IADL-physical, and IADL-cognitive subdomains (κ = .51–.66). Those who reported being able at baseline also performed better on physical- and cognitive-performance tests. Those with variable performance between test occasions tended to report inconsistently on repeat measures in mobility and IADL-cognitive, suggesting fluctuations in physical and cognitive performance.
Wang and Chen are with the School of Physical Therapy, and Li, the Dept. of Psychology, Chung Shan Medical University, Taichung, Taiwan. Hu is with the School of Physical Therapy, National Taiwan University, Taipei, Taiwan.