Modified Ashworth scale and spasm frequency score in spinal cord injury: reliability and correlation

• Published in: Spinal cord 2016-09, Vol.54 (9), p.702-708
• Main Authors: Baunsgaard, C B, Nissen, U V, Christensen, K B, Biering-Sørensen, F
• Format: Article
• Language: English
• Subjects: 692/308; 692/617; Adolescent; Adult; Aged; Aged, 80 and over; Anatomy; Biomedical and Life Sciences; Biomedicine; Denmark; Disability Evaluation; Female; Human Physiology; Humans; Male; Middle Aged; Muscle Spasticity - diagnosis; Muscle Spasticity - etiology; Neurochemistry; Neuropsychology; Neurosciences; original-article; Reproducibility of Results; Retrospective Studies; Severity of Illness Index; Spinal Cord Injuries - complications; Statistics, Nonparametric; Young Adult
• ISSN: 1362-4393; 1476-5624
• DOI: 10.1038/sc.2015.230

Study design: Intra- and inter-rater reliability study. Objectives: To assess intra- and inter-rater reliability of the Modified Ashworth Scale (MAS) and Spasm Frequency Score (SFS) in lower extremities in a population of spinal cord-injured persons, as well as correlations between the two scales. Setting: Clinic for Spinal Cord Injuries, Rigshospitalet, Hornbaek, Denmark. Methods: Thirty-one persons participated in the study and were tested four times in total with MAS and SFS by three experienced raters. Cohen’s kappa ( κ ), simple and quadratic weighted (nominal and ordinal scale level of measurement), was used as a measure of reliability and Spearman’s rank correlation coefficient for correlation between MAS and SFS. Results: Neurological level ranged from C2 to L2 and American Spinal Injury Association impairment scale A to D. Time since injury was (mean±s.d.) 3.4±6.5 years. Age was 48.3±20.2 years. Cause of injury was traumatic in 55% and non-traumatic for 45% of the participants. Antispastic medication was used by 61%. MAS showed intra-rater κ simple =−0.11 to 0.46 and κ weighted =−0.11 to 0.83. Inter-rater κ simple =−0.06 to 0.32 and κ weighted =0.08 to 0.74. SFS showed intra-rater κ weighted =0.94 and inter-rater κ weighted =0.93. Correlation between MAS and SFS showed non-significant correlation coefficients from−0.11 to 0.90. Conclusion: Reliability of MAS is highly affected by the weighting scheme. With a weighted- κ it was overall reliable and simple- κ overall unreliability. Repeated tests should always be performed by the same rater and in a very standardized manner. SFS was found reliable. MAS and SFS are poorly correlated, and ratings were inversely distributed and suggest that it assesses different aspects of spasticity.