Temporal evolution of remission following multiple sclerosis relapse and predictors of outcome

Relapse is a characteristic clinical feature of multiple sclerosis (MS) and is commonly employed as a measure of efficacy following therapeutic intervention. However, less is known about the temporal evolution of subsequent disability or factors predicting recovery.

The objective of this study was to assess the pattern of recovery following relapse and identify factors which predict recovery and residual disability following relapse.

A total of 226 relapses were studied prospectively in a cohort of 144 patients with standardised clinical assessments of physical disability including Expanded Disability Status Scale (EDSS), 10-m timed walk, 9-hole peg test and Multiple Sclerosis Impact Scale (MSIS-29) at 0, 2, 6 and 12 months. A total of 82 patients completed 12 months of follow up without further relapse.

Thirty per cent of relapses were severe (change in EDSS >2.0) of which 11% failed to recover. All measures showed significant improvement at 2 months but additional improvement was also observed in 9-hole peg test and MSIS-29 up to 12 months following initial assessment. Mean time to second relapse was 382 days. The only predictor of relapse severity in the model tested was younger age; however, increasing age and initial relapse severity were also predictors of poor outcome.

This study shows that the majority of improvement in physical disability following relapse occurs by 2 months but that more subtle recovery can take place over 12 months in a small sub-group of patients. These data will aid in patient counselling and will also inform the timing of therapeutic intervention and physical support.