Correlation of the clinical rating scale for tremor with a global assessment

The Fahn-Tolosa-Marín Clinical Rating Scale for Tremor (CRST) includes three parts (tremor severity, motor task performance, functional disability) and a separate global assessment of impairment completed by both the patient and examiner. Although the CRST is used to determine tremor severity and the efficacy of treatments for tremor, the instrument may not sufficiently capture the patient's perspective. The objective of this study was to determine the association of the CRST subpart and total scores with the global assessment.

This cross-sectional study included patients with essential tremor who completed a CRST within a tertiary health system electronic health record from 2013 to 2023. The global assessment was rated on a 0-100 % (most severe impairment) scale.

116 patients were included. The total CRST score was significantly associated with the examiner-reported global assessment (Spearman's correlation coefficient (ρ) 0.63, 95 % confidence interval (CI) 0.51 - 0.73, p < 0.001) but not the patient-reported global assessments (ρ 0.15, 95 % CI -0.04 - 0.33, p = 0.13). There were no significant associations between Part A, B, or C sub-scores and the patient-reported global assessments.

CRST scores have a stronger association with the examiner-reported global assessment than the patient-reported global assessment. The impact of tremor may be determined by functional detriments not readily measured with the CRST. By using the global assessments as a standard for comparison, our findings call into question the relevance of the CRST total scores and sub-scores as an accurate patient-centered outcome metric.