Outcome Measurement and Spasticity

The studies reviewed in this chapter involve a variety of outcome measures, of which only some are widely used clinically (e.g. Spinal Cord Injury Spasticity Evaluation Tool (SCI-SET), Ashworth Scale (AS) and Modified Ashworth Scale (MAS). However, there are many outcome measures used in published trials that not well understood by the majority of clinicians which cause confusion when comparing studies and treatments. It is important to develop agreement on clinically meaningful outcome measures for demonstrating the efficacy of an experimental therapeutic intervention (Steeves et al. 2007).Outcome measure feasibility is another important consideration given that clinicians commonly do not have consistent access to specialized equipment, nor have sufficient time to administer highly technical methods in a clinical setting (e.g. Cybex; Franzoi et al. 1999). Very few studies included measures addressing quality of life despite the need to ensure that treatments are well tolerated as well as functionally and practically effective for individuals. However, Balioussis et al. (2014) provided a review of psychometric data for SCI specific spasticity outcome measures that assess its impact on quality of life. These authors conclude that Individual reported impact of spasticity measure is the current best option because it accounts for more affective reactions in the presence of spasticity compared to SCI-SET with less available psychometric data. Balioussis et al. (2014) also put forth that despite good clinical feasibility, the AS and MAS known poor inter-rater and intersession reliability may shed doubt on their applicability for SCI, especially with respect to quality of life. Having a psychometrically-validated outcome assessment for spasticity related quality of life will be beneficial, especially for understanding of interactions between the clustering of spasticity with chronic pain and depression in people with SCI.

The gold-standard for clinical testing is the double-blind, randomized, placebo-controlled study design, particularly for the measurement of short-term treatment effects. However, the results of a well-designed trial are more easily interpreted if the outcome measures used follow outcome measure standards as outlined by Pierson (1997). In summary, effective outcome measures should be selected based on 1) understandability for administration/scoring/interpretation and validity/reliability; 2) relevancy to the clinical situation and population measured; 3) having a reasonable risk-benefit ratio; 4) requirement for strict adherence to test conditions and procedures; and 5) practicality in terms of personnel, time, equipment, cost, space and impact on the subject. No single outcome measure can capture the multi-dimensional nature of spasticity. Therefore, it is important, not only to choose an effective outcome measure but also to choose effective outcome measures to monitor the range of medical outcomes as suggested by Goldberg (1991): 1) technical outcome (i.e., reduction of spasm frequency); 2) functional outcome; 3) individual satisfaction and; 4) cost effectiveness. Consensus has not yet been reached on clinically meaningful, feasible and effective outcome measures relevant to the treatment of spasticity and individual reported outcomes.

Some of the measures that have been tested for various aspects of spasticity and for validity and/or reliability include the Ashworth (Ashworth 1964) and MAS (Bohannon & Smith 1987; Haas et al. 1996) spasticity scales, the PSFS (Penn 1988; Priebe 1996), the Pendulum test (Nance 1994), the Spinal Cord Assessment Tool for Spasticity (SCATS; Benz et al. 2005), the Spastic Paraplegia Rating scale (Schϋle et al. 2006), and the SCI-SET(Adams et al. 2007). Please refer to the SCIRE chapter, Outcome Measures, for a more in-depth discussion on these measures.