Long-term worsening of different body functions in persons with progressive multiple sclerosis

Abstract

Background It is unclear whether EDSS is responsive to disability worsening in advanced MS. Objective To explore the dynamics of disability worsening in persons with advanced-stage MS (EDSS ≥5.5) using three disability worsening definitions (EDSS, Rivermead Mobility Index (RMI), 9-Hole Peg Test (9-HPT)). Methods EDSS-, RMI- and 9-HPT-based disability worsening were assessed over a minimum of two years in a cohort of 286 persons with advanced MS attending inpatient rehabilitation using Kaplan-Meier Curves and multivariable Cox regression. Furthermore, the correspondence between EDSS-, RMI- and 9-HPT-based disability worsening was analyzed. Results Disability progression was observed in 49% (9-HPT), 52% (EDSS) and 53% (RMI), with 9-HPT-based worsening slightly lagging behind. The Multiple Sclerosis Severity Score (MSSS) was the only consistent factor predicting disability worsening based on all three definitions (EDSS: hazard ratio 1.48 [1.30;1.68]; RMI: 1.12 [0.99;1.27]; 9-HPT: 1.36 [1.18;1.57]). Correspondence between EDSS and the other definitions (9-HPT and RMI) was 44.3% and 55.7% at time of EDSS progression and 65.1% and 72.5% overall, respectively. Conclusion In persons with advanced-stage MS, half still developed disability worsening in different functional systems over a median of 6 years. MSSS seems a valid predictor for disability worsening in all three outcome measures in advanced MS.