Objectives: To better understand disablement and transitions from impairment to disability, discrete valid measures of functional limitation are needed. This study reports the development and criterion-related validity of scales that quantify severity of upper and lower extremity functional limitation.
Methods: Data are from 3,635 cognitively intact community-dwelling women aged 65 years and older and 1,002 moderately to severely disabled participants in the Women's Health and Aging Study. Scales assessing severity of upper and lower extremity functional limitation were constructed from commonly available questions on functional difficulty. Criterion-related validity was evaluated with self-report and performance-based measures.
Results: The upper and lower extremity scales range from 0 to 6 and 0 to 9, respectively. Scale scores were well distributed in the disabled group and discriminated limitations in the broader community. For both scales, rates of difficulty for all ADL and IADL increased (p<.001) with increasing severity score, and percent able and mean performance on respective upper and lower extremity tasks decreased (p<.01).
Discussion: These scales, constructed from commonly used self-report measures of function, provide discrete measures of upper and lower functional limitation. Because these scales are distinct from measures of disability and impairment, their use should facilitate increased understanding of the disablement process.