Ped-MSSS Provides Alternative to EDSS in Pediatric-Onset Multiple Sclerosis

Compared to those with adult-onset multiple sclerosis (MS), patients with pediatric-onset multiple sclerosis (POMS) may present with lower scores using the Expanded Disability Status Scale (EDSS), according to study results published in Neurology. Furthermore, the study results suggest that the pediatric multiple sclerosis severity score (Ped-MSSS) may serve as alternative to EDSS in patients with POMS.

The goal of this study was to better understand disability scoring according to EDSS in patients with POMS, and to develop a scale for assessing disability in this population using an algorithm similar to the previously published Multiple Sclerosis Severity Score (MSSS).

The multicenter retrospective study included prospectively collected data on 873 subjects (66% women; mean age at diagnosis, 13.6 years) with POMS from 12 centers of the U.S. Network of Pediatric MS Centers.

During mean of follow-up period of 4.3 years, an EDSS of 2.0 at any time point was reported in 52% of patients with POMS, while EDSS of 3.0 and 6.0 were reported in 19.4% and 1.5% of all patients, respectively.

At these EDSS milestones, the cohort of patients with POMS was significantly different from those with adult-onset MS; Ped-MSSS scores were much higher compared with MSSS scores at similar disease duration time points. In the POMS cohort, an EDSS of 2.0, 3.0, and 6.0 corresponded to decile scores of 8.00/9.46/9.94, 7.86/9.39/9.91, and 7.32/9.01/9.78 at 2, 5, and 10 years post-onset, respectively. In comparison, in the previously published adult data, decile scores of 5.24/7.27/9.59, 3.90/5.79/8.83, and 2.34/3.79/7.39 were reported at 2, 5, and 10 years post-onset, respectively.

Linear Regression model comparing EDSS scores to Ped-MSSS decile at 5 years showed that in both models, “ever having a motor relapse” and EDSS at year 1 were significant predictors of disease progression. In the Ped-MSSS model, “ever having a sensory relapse” was found to be an additional predictor of disease severity.

Of all study participants, 500 had a Symbol Digit Modalities Test analysis at any time point. There was a significant inverse association between test scores with duration of disease activity and cerebral function score.

The study had several limitations, including potential recall bias, severity bias, geographic and socio-economic bias, and possible inter-rater differences in EDSS assessment. In addition, comparisons were made from different epochs in MS and POMS care; consequently, the results may be skewed due to data collection in a lower-efficacy treatment era. 

“This is the first study of its kind to assess disease severity and disability in the context of disease duration in POMS, and the model studied has the potential to more sensitively assess changes in disease state and/or response to therapeutic intervention in this unique population,” concluded the researchers.

Disclosure: Several study authors declared affiliations with the pharmaceutical industry. Please see the original reference for a full list of authors’ disclosures.

Reference

Santoro JD, Waltz M, Aaen G, et al. Pediatric multiple sclerosis severity score in a large U.S. cohort. Neurology. Published online July 20, 2020. doi:10.1212/WNL.0000000000010414