Hughes J, et al. - In this longitudinal, prospective cohort study, researchers investigated the relationship of superimposed relapses in progressive-onset multiple sclerosis (MS) on disease outcomes. Findings suggested an association of superimposed relapses with a lower risk of confirmed disability progression in progressive-onset MS. In patients with progressive-onset MS, disease-modifying therapy might prevent relapse-related disability accrual. Data reported that inflammatory relapses are a significant and modifiable determinant of disability accrual in progressive-onset disease.

Methods

• Observational cohort study by MSBase, an international database collected prospectively.
• From January 1995 to February 2017, data were collected.
• In February 2017, analysis began.
• One thousand, four hundred nineteen eligible patients( 31.9%) were identified for analysis out of 44,449 patients at the time of extraction.
• Inclusion criteria included primary progressive MS (PPMS) or progressive-relapsing MS (PRMS), adult-onset disease, and minimum data set (including ≥3 visits with disability recorded, ≥3 months between second and last visit).
• Using multivariable regression models (Andersen-Gill) with mixed effects, data were analyzed.
• Two sensitivity analyses were performed to exclude both relapse-related disability progression and bout-onset progressive MS.
• Grouped according to presence or absence of relapse, characterized as an acute episode of clinical worsening.
• To confirm relapse, quantifiable disability change or correlation on imaging was not needed.
• Main outcome and measure included cumulative hazard of disability progression.

Results

• As compared to patients with PPMS (mean [SD] age, 46 [15] vs 51 [10] years, Cohen d = 0.40) and showed a mean lower Expanded Disability Status Scale score (mean [SD] score, 4.0 [3] vs 4.5 [2.5], Cohen d = 0.28) at inclusion, those with PRMS were younger.
• The ratio of men to women in the PRMS and PPMS groups (252:301 vs 394:472) was comparable.
• The overall mean (SD) age for men was 48 (11) years and for women was 50 (10).
• In patients with superimposed relapses (hazard ratio [HR], 0.83; 95% CI, 0.74-0.94; P=.003), likelihood of confirmed disability progression was lower.
• The proportion of follow-up time spent on disease-modifying therapy significantly reduced the risk of confirmed progression of disability in the relapse cohort (HR, 0.96; 95% CI, 0.94-0.99; P=.01), however, not in those without relapse (HR, 1.02; 95% CI, 0.99-1.05; P=.26).
• The association of disease-modifying therapy in the cohort with superimposed relapse was no longer observed (HR, 1.10; 95% CI, 0.96-1.24; P=.16) when accounting for relapse-related progression.