Measuring the inch stones for progress: Gross motor function in the developmental and epileptic encephalopathies

Objective: Developmental and epileptic encephalopathies (DEE) entail moderate to profound impairments in gross motor skills and mobility, which are poorly quantified with clinical outcomes assessments (COA) used in neuro-typical populations. We studied the motor domain of the Adaptive Behavior Assessment System-3 for ages 0-5 years (ABAS) used outside of its intended age range with a focus on raw scores.

Methods: In a cross-sectional survey, 117 parents of children with a variety of DEEs (ages 1-35 years, median = 9) completed the motor domain section of the ABAS. Floor and ceiling effects and associations with epilepsy-related factors were assessed with appropriate parametric and nonparametric statistical techniques. The sensitivity of the ABAS and additional measures of mobility borrowed from the cerebral palsy literature (Functional Activities Questionnaire (FAQ-22) walking level (FAQ-WL)) to different levels of the Functional Mobility Scale was determined.

Results: ABAS motor scores corresponded to a median age equivalent of 20.5 months (Inter-Quartile Range (IQR) 8-34). Most raw scores corresponded to standardized scores > 2 standard deviations below the ABAS standardization sample mean. ABAS raw scores demonstrated minimal floor and ceiling effects (<5%). In linear regression models, scores increased with age under 6 years (p < 0.0001) but flattened out thereafter. Scores varied substantially by DEE group (p < 0.001) and decreased with higher convulsive seizure frequency (<0.0001) and number of seizure medications (p < 0.001). ABAS and other motor scores were sensitive to important differences in mobility as represented by the FMS at 5 yards. Further, they correlated with declines in mobility function from 5 to 500 yards.

Significance: An out-of-range COA with raw scores may provide a measure of motor ability and mobility sensitive within the range of moderate to profound impairment seen in patients with DEE. This approach could shorten the time to appropriate COA development and ensure timely clinical trial readiness for novel therapies for rare DEEs.