Development of the Graded Redefined Assessment of Strength, Sensibility and Prehension (GRASSP): reviewing measurement specific to the upper limb in tetraplegia

Abstract

Primary outcome measures for the upper limb in trials concerning human spinal cord injury (SCI) need to distinguish between functional and neurological changes and require satisfying psychometric properties for clinical application. The Graded Redefined Assessment of Strength, Sensibility and Prehension (GRASSP) was developed by the International GRASSP Research and Design Team as a clinical outcome measure specific to the upper limbs for individuals with complete and incomplete tetraplegia (that is, paralysis or paresis). It can be administered across the continuum of recovery after acute cervical SCI. An international multicenter study (involving centers in North America and Europe) was conducted to apply the measure internationally and examine its applicability. The GRASSP is a multimodal test comprising 5 subtests for each upper limb: dorsal sensation, palmar sensation (tested with Semmes-Weinstein monofilaments), strength (tested with motor grading of 10 muscles), and prehension (distinguishes scores for qualitative and quantitative grasping). Thus, administration of the GRASSP results in 5 numerical scores that provide a comprehensive profile of upper-limb function. The established interrater and test-retest reliability for all subtests within the GRASSP range from 0.84 to 0.96 and from 0.86 to 0.98, respectively. The GRASSP is approximately 50% more sensitive (construct validity) than the International Standards of Neurological Classification of SCI (ISNCSCI) in defining sensory and motor integrity of the upper limb. The subtests show concurrence with the Spinal Cord Independence Measure (SCIM), SCIM self-care subscales, and Capabilities of Upper Extremity Questionnaire (CUE) (the strongest concurrence to impairment is with self-perception of function [CUE], 0.57-0.83, p < 0.0001). The GRASSP was found to demonstrate reliability, construct validity, and concurrent validity for use as a standardized upper-limb impairment measure for individuals with complete or incomplete tetraplegia. Responsiveness (follow-up from onset to 1 year postinjury) is currently being tested in international studies (in North America and Europe). The GRASSP can be administered early after injury, thus making it a tool that can be administered in acute care (in the ICU), rehabilitation, and outpatient clinics.