Test-retest reliability of the Dyskinesia Impairment Scale: measuring dystonia and choreoathetosis in dyskinetic cerebral palsy

Abstract

Aim: To assess test-retest reliability of the Dyskinesia Impairment Scale (DIS) in children and young adults with dyskinetic cerebral palsy (CP).

Method: Dystonia and choreoathetosis were assessed in 15 participants with dyskinetic CP (13 males, 2 females; age range 5-22y, mean 14y, SD 4y) using the DIS in two separate sessions over 7 days. Exclusion criteria were changes in muscle relaxant medication within the previous 3 months, orthopaedic or neurosurgical interventions within the previous year, and spinal fusion. Intraclass correlation coefficient, confidence intervals (CI), standard error of measurement, and the minimal detectable difference (MDD) were determined for test-retest reliability.

Result: Intraclass correlation coefficients of the DIS, the dystonia subscale of the DIS, and the choreoathetosis subscale of the DIS were 0.98 (95% CI 0.94-0.99), 0.97 (95% CI 0.92-0.99), and 0.96 (95% CI 0.90-0.99). The standard error of measurement and MDD were 2.6% and 7.2%.

Interpretation: The DIS is a reliable tool to assess dystonia and choreoathetosis; it remains stable over time in children and young adults with dyskinetic CP. These results add to the current evidence for good clinimetric properties of the DIS.

What this paper adds: The Dyskinesia Impairment Scale (DIS) shows stability in scoring dystonia and choreoathetosis. The total DIS score and dystonia and choreoathetosis subscales are clinically useful.