The spasticity-related quality of life 6-dimensions instrument in upper-limb spasticity: Part II A first psychometric evaluation.

Abstract

ObjectivePsychometric evaluation of the Spasticity- related Quality of Life 6-Dimensions instrument (SQoL-6D).DesignA clinimetric evaluation conducted in a multicentre, prospective, longitudinal cohort study at 8 UK sites.PatientsAdult patients (n = 104) undergoing focal treatment of upper-limb spasticity.MethodsThe SQoL-6D was administered in the clinic at enrolment and at 8 weeks, then 1–4 days later at home to assess test-retest reliability.ResultsThe SQoL-6D demonstrated adequate construct validity and unidimensionality of the scale, allowing the calculation of a Total score. Cronbach’s alpha (0.74) supported the internal consistency reliability, while the intraclass correlation coefficient supported test-retest reliability (0.82). Correlation coefficients with established instruments supported convergent validity, while significant differences between known-groups (of differing clinical severity) in SQoL-6D Total score confirmed its sensitivity to both cross-sectional and longitudinal differences.ConclusionThe SQoL-6D is a promising new measure to assess health status for patients with upper-limb spasticity of any aetiology. Further investigation and exploration of the allocation of weights to convert the SQoL-6D to a health-related quality of life utility index, are required.LAY ABSTRACTIn upper-limb spasticity, the use of the arm and hand become restricted due to “tight” muscles. Although questionnaires to assess a person’s quality of life have been developed, they do not specifically assess the impact of upper-limb spasticity. To address this deficiency, the Spasticity-related Quality of Life 6-Dimensions (SQoL-6D) questionnaire was developed (see also the companion “development” paper available in this issue). To test that the SQoL-6D works as expected, it was completed by 104 people living with spasticity and compared with other questionnaires they completed. The results show that the SQoL-6D questions are relevant to people with spasticity. The answers were reliable when the SQoL-6D was repeated, and differences in the burden of spasticity between people grouped by the severity of their condition were captured accurately. The SQoL-6D is a promising new measure to assess aspects of quality of life in people living with spasticity.