Multiple sclerosis relapses: a multivariable analysis of residual disability determinants

BACKGROUND: Recovery from multiple sclerosis (MS) relapses is variable. The factors influencing persistence of residual disability (RD) after a relapse are still to be thoroughly elucidated. AIMS OF STUDY: To assess RD after MS relapses and to define the factors associated with persistence of RD. METHODS: Data were retrospectively collected for all relapses in a population of relapsing-remitting MS patients during 3 years. Relapse severity and RD after 1 year were calculated on Expanded Disability Status Scale basis. A multivariable analysis for factors influencing RD and relapse severity was performed (variables: age, gender, disease duration, oligoclonal bands, relapse severity, monosymptomatic/polysymptomatic relapse, immunomodulating treatment, incomplete recovery at 1 month). RESULTS: A total of 174 relapses were assessed. RD after 1 year was observed in 54.5% of the relapses. Higher risk of RD was associated with occurrence of a severe relapse (P = 0.024). Incomplete recovery at 1 month was highly predictive of RD at 1 year (P < 0.0001). Risk of a severe relapse was associated with age <or= 30 years (P = 0.025) and inversely associated with the use of immunomodulating treatment (P = 0.006). CONCLUSIONS: Incomplete recovery at 1 month is a predictor of long-term persistence of RD. Higher relapse severity is associated with higher risk of RD. Risk of severe relapses is lower in patients treated with immunomodulating drugs.