To assess the effect of eculizumab on disability worsening and quality of life (QoL) in patients with neuromyelitis optica spectrum disorder (NMOSD).

Eculizumab, a terminal complement inhibitor, significantly reduced relapse risk versus placebo in PREVENT (NCT01892345), a phase 3, randomized, double-blind study in adults with aquaporin-4 immunoglobulin G-positive NMOSD. Disability and QoL were measured during PREVENT using the Expanded Disability Status Scale (EDSS; higher scores = worse disability) and the 36-item Short-Form Health Survey (SF-36; lower scores = worse QoL), respectively.

Patients received eculizumab (maintenance dose, 1200 mg/2 weeks) or placebo. Concomitant immunosuppressant therapy (excluding rituximab and mitoxantrone) was permitted if doses were stable at baseline. The association between baseline SF-36 and baseline EDSS scores (low score, < 4.0; high score, ≥ 4.0; data pooled across treatment groups) and between-group differences in EDSS worsening at study end (increase of ≥ 2.0, ≥ 1.0 and ≥ 0.5 from baseline scores of 0, 1.0–5.0 and ≥ 5.5, respectively) were analyzed post hoc. Analyses of changes from baseline to study end in SF-36 scores were prespecified (tertiary endpoint).

At baseline, patients with higher EDSS scores (greater disability; n = 79) had significantly worse SF-36 physical component summary (PCS) scores than those with lower EDSS scores (n = 64; 34.02 vs 42.96, respectively; p < 0.0001). At study end, the proportion of patients with worsening EDSS scores was significantly lower for eculizumab (11.5%; n = 96) than for placebo (23.4%; n = 47; odds ratio: 0.381; 95% confidence interval: 0.146–0.997; p = 0.0493). Improvements were significantly greater with eculizumab than placebo for SF-36 PCS, physical functioning and role limitations owing to physical health scores (all p < 0.05).

Eculizumab significantly reduced disability worsening and improved some aspects of QoL compared with placebo in patients with NMOSD.