Relationship between various clinical outcome assessments in patients with blepharospasm

Abstract

The objective was to analyze the metric properties of the Jankovic Rating Scale (JRS) and a self-rating patient response outcome scale, the Blepharospasm Disability Index (BSDI), in blepharospasm patients. Data from a randomized, double-blind, active-control clinical trial in 300 patients with blepharospasm treated with either botulinum toxin type A (Botox) or NT201 (Xeomin) were used to evaluate the metric properties of the JRS and the BSDI compared with the Patient Evaluation of Global Response (PEGR) and Global Assessment Scale (GAS). The internal consistency of the BSDI was high, Cronbach's Alpha = 0.88, and the retest reliability of the BSDI single items was adequate, Spearman's rank coefficient = 0.453 < r < 0.595. The correlation between JRS sum score and BSDI weighted mean score was r = 0.487 (baseline) and r = 0.737 (control visit), respectively. Using the GAS and PEGR, the results suggest that a change of 2 points in the JRS and of 0.7 points in the BSDI are clinically meaningful. JRS and BSDI are objective indicators of clinical efficacy as suggested by their good validity when compared with physicians' and patients' rating scales. Both, JRS and BSDI, can be used to reliably assess blepharospasm in treatment trials.