Validation of the NARCOMS Registry: Tremor and Coordination Scale

Tremor secondary to multiple sclerosis (MS) can be severely disabling but remains understudied. The development of brief, acceptable patient-reported measures of tremor could facilitate further study. We aimed to assess the criterion and construct validity of the Tremor and Coordination Scale (TACS) used by the North American Research Committee on Multiple Sclerosis (NARCOMS) Registry. Forty-four patients with MS completed the TACS and Performance Scales and underwent a neurologic examination (Expanded Disability Status Scale; EDSS) and evaluation with the Multiple Sclerosis Functional Composite (MSFC). We assessed criterion and construct validity with Spearman rank correlations between the TACS and the following measures: EDSS, Nine-Hole Peg Test (NHPT) of the MSFC, age, body-mass index (BMI), the hand function and mobility domains of the Performance Scales, and the Physical and Mental Composite Scores of the 36-item Short Form Health Status Survey (SF-36). The median (interquartile range; IQR) score on the TACS was 1 (0.5-2.0). The TACS correlated moderately with the cerebellar Functional System Score (FSS) (r = 0.51; 95% confidence interval [CI], 0.24-0.70) and with the NHPT (r = -0.51; 95% CI, -0.70 to -0.29). The TACS correlated with the hand (r = 0.60; 95% CI, 0.36-0.76) and mobility (r = 0.56; 95% CI, 0.31-0.73) domains of the Performance Scales. The TACS did not correlate significantly with age (r = -0.11; 95% CI, -0.40 to 0.19) or BMI (r = 0.15; 95% CI, -0.15 to 0.43). These findings support the criterion and construct validity of the TACS. Further evaluation is needed to establish the test-retest reliability of the scale and its responsiveness to change.