"Why do I say this?"
The following study investigated the relationship between relapses and disability progression for outcomes of requiring assistance to walk, being bedridden and dying from MS; i.e. EDSS 6, 8 or 10 respectively.
This group has previously shown no effect of relapse frequency among progressive MS subtypes (a post that caused many comments).
In this study, however, the researchers examined these measures in the relapsing-remitting phase.
Frequent relapses in the first 2 years and a shorter interval between early attacks predicted shorter times to reach disability endpoints.
For example, MS'ers with one attack in the first 2 years took 7.6, 12.8 and 20.3 years longer to reach EDSS 6, 8 and 10, respectively, when compared to MS'ers with 3 or more attacks in the fist 2 years.
Relapse frequency beyond year 2 did not predict the key outcome of secondary progression or times to EDSS 6, 8 or 10.
Conclusion: This study suggests there are two distinct disease phases related to late disability outcomes and that theses phases appears to be separated by a watershed within the relapsing-remitting phase, just a few years after clinical onset.
Scalfari et al. The natural history of multiple sclerosis: a geographically based study 10: relapses and long-term disability. Brain. 2010 Jul;133(Pt 7):1914-29.
"Therefore suppressing early relapses within the first two years of disease onset may be more effective in modifying later disease progression than suppressing relapses after the first two years from disease onset. This may explain the different efficacy results between the phase 2 and phase 3 Alemtuzumab trials; the phase 2 trial recruited subjects within 3 years of disease onset and the phase 3 trial within 5 years of disease onset."
"It will be very interesting to see the sub-group analysis of the phase 3 Alemtuzumab trial comparing study subjects with a disease duration of less than 2 years with those with a disease duration of more than 2 years. Any bets on the results?"