Course of relapsing-remitting multiple sclerosis before, during and after natalizumab.

The consequences of interruption of natalizumab treatment are incompletely known. The objective was to assess the confirmed annualized relapse rates for patients preceding initiation, during and following suspension of natalizumab therapy. A chart review was conducted and data were analyzed using the Generalized Estimating Equations. During natalizumab therapy the confirmed annualized relapse rate was 0.08, compared to 0.52 (p = 0.0003) during the prior 12 months and to 0.35 (p =  0.0032) during the following 3 to 24 months. Similar results were found when confirmed and unconfirmed were analyzed. To conclude, following cessation of natalizumab therapy disease activity rapidly returned to pre-natalizumab levels.