A new study in Brazil reports that risk factors for treatment failure among MS patients are comparable to those reported for patients in the northern hemisphere (Damasceno et al. J Neurol Sci 2013;324:29-33).

The time to reach EDSS 6 and 7 was 25.83 years and 36.25 years, respectively. Significant risk factors for EDSS progression were brainstem symptoms at onset (13-fold increased risk), motor symptoms at onset (8-fold increase), and male sex (4-5 fold). The number of relapses in the first five years post-diagnosis was associated with only a slight increase (1.28) in the risk of progression.

Other studies have also underscored the prognostic importance of motor relapses, sphincteric symptoms, multifocal symptoms, relapse severity and incomplete recovery (Bergamaschi et al. J Neurol Sci 2001;189:13-21; Leone et al. Mult Scler 2008;14:485-493).

Relapse frequency also has had prognostic significance in some studies (Hirst et al. J Neurol 2008;255:280-287). However, the UBC group found that although one or more relapses in the first five years post-diagnosis was important, the number of relapses became less important 5-10 years after diagnosis (Tremlett et al. Neurology 2009;73:1616-1623; free full text at www.ncbi.nlm.nih.gov/pmc/articles/PMC2881858/pdf/7121.pdf). This suggests that there is a limited time window to potentially alter the disease course with the current immunomodulatory therapies.

The times to EDSS 6 or 7 in the Brazilian study are similar to those reported by the Lyons group (23.1 years for EDSS 6, 33.1 years for EDSS 7) (Confavreux et al. N Engl J Med 2000;343:1430-1438), indicating that the natural history of MS is similar in this Latin American population.

Comment
Dr. François Grand’Maison: Relapses matter. They are the major defining feature of MS. Clinically evident residual signs persist in at least 40% of relapses. It is therefore always important to prevent relapses regardless of the stage of disease. Whether frequent relapses accelerate the onset of the progressive phase of MS or not is a different but important issue, for which we do not yet have an answer.