The capabilities of upper extremity instrument: reliability and validity of a measure of functional limitation in tetraplegia

Abstract

Objective: To evaluate the reliability and validity of the Capabilities of Upper Extremity (CUE) instrument, designed to measure upper extremity functional limitations in individuals with tetraplegia. Functional limitations are actions such as reaching or grasping and are a link between the domains of impairment and disability. Design: Survey of people with chronic spinal cord injury. Setting: Regional spinal cord injury center. Subjects: One hundred fifty-four individuals (140 male) with tetraplegia at least 1 year after injury and followed by the center. Mean age was 36.7 years (SD = 11.1). Sixty-eight percent were motor complete. Methods: The 32-item CUE was administered by telephone interview twice about 2 weeks apart. The motor portion of the Functional Independence Measure (FIM sm) was collected during the first interview. Upper extremity motor scores and motor levels were obtained from the most recent assessment in the outpatient chart. The instrument was evaluated for internal consistency, reliability, and validity. Exploratory factor analysis was performed to examine scale structure. Results: Homogeneity of the scale was excellent. Cronbach's α was .96, and item-total correlations ranged from .49 to .78. Test-retest reliability was high (ICC = .94). All but three items had desired levels of agreement (κ > .60). Analysis of variance indicated that the CUE distinguished between motor levels of tetraplegia more than one level apart. The CUE was correlated highly with both motor scores and FIM. Regression analysis indicated that the CUE was better than upper extremity motor scores for predicting FIM scores. The model containing the CUE explained 73% of the variance in FIM and was not enhanced by the addition of motor scores. Factor analysis suggested four potential subscales: arm function (bilateral), right hand function, left hand function, and reaching down. Conclusion: The CUE exhibits good homogeneity, reliability, and validity; further work is needed to determine its sensitivity to change in function.