Functional tests may help track pediatric FA disease progression
Study: Range of assessments tailored to patient population is critical
Functional assessments, such as a test of how far an individual can walk in one minute, may be useful for tracking disease progression in children with Friedreich’s ataxia (FA), a study reports.
“Our study overall emphasizes the importance of integrating a range of outcome assessments tailored to the specific needs and characteristics of the pediatric population with Friedreich ataxia,” researchers wrote.
The study, “Disease Progression in Children With Friedreich Ataxia: Functional Performance and Other Outcome Assessments in the FACHILD Study,” was published in the Journal of Child Neurology.
Standard assessment may be less useful in pediatric FA patients
FA is a genetic disease characterized by loss of muscle control and coordination. Symptoms typically begin manifesting between the ages of 5 and 15.
Clinician-reported outcomes are currently the most sensitive measures to assess progression in FA and related disorders. However, the modified Friedreich’s Ataxia Rating Scale (mFARS), a standard assessment in FA clinical trials, may be less useful in younger children, according to the scientists. As such, researchers need to develop “other disease-relevant clinical outcome assessments of Friedreich ataxia for this age group.”
Focusing on children with FA, the research team drew on data from the FACHILD observational study (NCT03418740). The study enrolled 108 children, ages 6 to 18, with a genetically confirmed diagnosis of FA. For this analysis, the researchers focused on 89 FACHILD participants who could walk at the time they started the study.
Over three years of follow-up, participants completed performance outcome assessments, as well as clinician-reported and patient-reported outcome assessments. These included mFARS, timed function tests, and the Upright Stability Score (USS), a part of mFARS that measures sitting posture, stance, heel-to-toe walking, and gait.
Among the functional tests used, the 25-foot walk test, which measures how quickly participants could walk 25 feet, “captured disease progression most linearly,” according to the team, consistent with data from the FA Clinical Outcome Measures Study, or FACOMS (NCT03090789), a large natural history study.
Walking tests could be useful in tracking disease progression
Results further suggested that the one-minute walk test may also be an important instrument in this patient population. Its sensitivity to change was similar to that of the USS, though fewer participants completed the one-minute walk.
As for the nine-hole peg board test, which measures hand dexterity, it showed high sensitivity to change, as the investigators expected.
Overall, USS scores correlated strongly with mFARS scores and moderately with the Berg Balance Scale. The correlation was mild with the Friedreich Ataxia Activities of Daily Living Scale of functional impairment during everyday tasks, “demonstrating the different nature of clinician-reported outcome measures (and patient-reported outcome measures) versus performance outcome measures,” the scientists wrote.
This suggests that fatigue may play an important role independent of disability in Friedreich ataxia.
After one year, the most sensitive measures were the USS, the one-minute walk test, and the nine-hole peg board test.
Missed appointments due to COVID-19 contributed to missing data and represented a noteworthy study limitation, the investigators said. Participants with higher disability, as measured by USS, were more often unable to perform tests. Fatigue and refusal to complete tests for other reasons could occur at any level of disability.
“This suggests that fatigue may play an important role independent of disability in Friedreich ataxia,” the researchers wrote.
They added that walking tests hold promise in terms of tracking disease progression.
“In conclusion, the modified Friedreich Ataxia Rating Scale and the Upright Stability Score remain highly sensitive tools for tracking disease progression in Friedreich ataxia, but intermediate length walking tests such as the 1-minute walk offer promising utility,” the team concluded. “However, as our previous publications have demonstrated, these clinical outcome assessments are most sensitive in children [older than 10], and more work on novel clinical assessments that are developmentally appropriate [is] still required for the younger pediatric Friedreich ataxia population.”
About the Author
