Demographic and clinical characteristics of malignant multiple sclerosis

Multiple sclerosis (MS) that causes patients to require assistance for ambulation (Expanded Disability Status Scale [EDSS] ≥6) within 5 years from symptom onset is generally termed malignant. Malignant status can be transient (TM) or sustained until year 5 (SM). We studied the incidence, predictors, and demographic and clinical characteristics of malignant MS.

Patients with symptom onset in 2002-2005 and 5-year follow-up were selected from the Partners Multiple Sclerosis Center database. Patients with TM were further grouped into TM and SM. The mechanism of reaching EDSS 6 (relapse- vs progression-related) was determined.

A total of 487 patients were included (17 TM, 42 SM). The incidence proportion of ever malignant (EM=SM+TM) was estimated as 12.11% and SM as 8.62%. Patients with older age at onset, male gender, and positive smoking history were more likely to become SM. Compared to nonmalignant patients, the proportion of progressive-onset MS in the SM group was significantly higher, but not different in TM. Within relapsing-onset patients, most of TM, and a smaller proportion of the SM group had a relapse-related as opposed to progression-related mechanism. The final model predictors for EM vs nonmalignant were older age at onset, motor symptoms at onset, and progressive disease onset. Within the malignant patients, predictors of TM vs SM were younger age and brainstem symptoms at onset.

Over 10% of patients with MS experience a malignant course as defined above. Some demographic and clinical factors are found to predict a malignant outcome. MS in patients who reach a high EDSS based on disease progression is more likely to remain malignant.