Reliability and Validity of the Dyskinesia Impairment Scale in Children and Young Adults with Inherited or Idiopathic Dystonia

Abstract

Background: The Dyskinesia Impairment Scale (DIS) is a new assessment scale for dystonia and choreoathetosis in children and youth with dyskinetic cerebral palsy. Today, the Burke–Fahn–Marsden Dystonia Rating Scale (BFM) is mostly used to assess dystonia in children with inherited dystonia. The aim of this study was to assess reliability and validity of the DIS in children and youth with inherited or idiopathic dystonia. Methods: Reliability was measured by (1) the intraclass correlation coefficients (ICCs) for inter-rater and test-retest reliability, as well as (2) standard error of measurement (SEM) and minimal detectable difference (MDD). For concurrent validity of the DIS-dystonia subscale, the BFM was administered. Results: In total, 11 males and 9 females (median age 16 years and 7 months, range 6 to 24 years) were included. For inter-rater reliability, the ICCs for the DIS total score and the dystonia and choreoathetosis subscale scores were 0.83, 0.87, and 0.71, respectively. For test-retest reliability, the ICCs for the DIS total score and the dystonia and choreoathetosis subscale scores were 0.95, 0.88, and 0.93, respectively. The SEM and MDD for the total DIS were 3.98% and 11.04%, respectively. The Spearman correlation coefficient between the dystonia subscale and the BFM was 0.88 (p < 0.01). Conclusions: Good to excellent inter-rater, test-retest reliability, and validity were found for the total DIS and the dystonia subscale. The choreoathetosis subscale showed moderate inter-rater reliability and excellent test-retest reliability. The DIS may be a promising tool to assess dystonia and choreoathetosis in children and young adults with inherited or idiopathic dystonia.

The Dyskinesia Impairment Scale, Second Edition: Development, construct validity, and reliability

“…Sixty-nine percent of the attendees at the expert meeting wanted to reduce the number of body regions to be scored in the DIS but there was no obvious agreement as to which body region should be removed. Based on the high number of individuals unable to perform trunk actions and the previously reported low interrater reliability values, 12,14 the research team decided to delete the trunk region. Eighty-seven percent of the attendees were in favour of deleting one of the two actions to be scored.…”

“…It has shown good‐to‐excellent psychometric properties, suggesting that it is a promising tool in intervention studies and when objectively evaluating disease progression 9,12,13 . Recently, the DIS was also shown to be valid and reliable in children and young adults with inherited or idiopathic dystonia 14 . However, the DIS is time‐consuming to complete and therefore often disregarded in clinical practice.…”

“…9,12,13 Recently, the DIS was also shown to be valid and reliable in children and young adults with inherited or idiopathic dystonia. 14 However, the DIS is time-consuming to complete and therefore often disregarded in clinical practice. Furthermore, the result is presented as a percentage score, making comparison over time or between individuals complicated.…”