Disability progression in aggressive multiple sclerosis

Abstract

Objective: To examine disease progression in 'aggressive' multiple sclerosis (MS), British Columbia, Canada (1980-2009).

Methods: Aggressive (or 'malignant') MS was defined as Expanded Disability Status Scale (EDSS) ⩾6 within 5 years from onset. The first EDSS ⩾6 was termed 'baseline'. Within 2, 3 and 5 years post-baseline, patients were categorized as follows: 'worsened' or 'improved', relative to baseline EDSS (the remainder exhibited no change or had no new scores). The associations between patient characteristics (sex, relapsing onset/primary progressive, onset age, onset symptoms, disease duration, cumulative prior relapses and baseline EDSS) and worsening in disability were examined longitudinally using logistic regression.

Results: Of the 225/4341 (5.2%) aggressive/malignant MS patients, 134 (59.6%) were female, 167 (74.2%) were relapsing onset, 94 (41.8%) had received disease-modifying drugs at some point and the mean follow-up was 8.7 years. The proportion of patients who 'worsened' increased from 40.4% to 57.8%, while those who 'improved' varied little (range, 8.9%-10.2%). The odds of worsening increased with disease duration (adjusted odds ratio (AOR) = 1.36; 95% confidence interval (CI) = 1.22-1.52) and the presence of primary progressive (vs relapsing-onset) MS (AOR = 1.85; 95% CI = 1.01-3.38).

Conclusion: Apart from disease duration and a primary progressive course, no clinically useful associations of subsequent disease worsening in patients with aggressive/malignant MS were identified.

Keywords: Multiple sclerosis; epidemiology; neuroepidemiology.