Nabiximols is Efficient as Add-On Treatment for Patients with Multiple Sclerosis Spasticity Refractory to Standard Treatment: A Systematic Review and Meta-Analysis of Randomised Clinical Trials

Background: Spasticity affects 54% of multiple sclerosis (MS) patients at disease onset, but this rate gradually increases with disease progression. Spasticity does not fully respond to standard treatment in one-third of the patients. Objective: Our systematic review and meta-analysis assessed whether add-on nabiximols, can improve MS-associated refractory spasticity. Methods: The systematic literature search was performed in Web of Science, MEDLINE, Scopus, CENTRAL, and Embase, on 15/10/2021, without restrictions. We included in the review blinded, randomized, placebo-controlled trials evaluating the efficacy of nabiximols in adult MS patients with refractory spasticity, by comparison with placebo. The primary outcome was responder rate by spasticity numerical rating scale (NRS). Secondary outcomes were spasticity-related parameters. We used random effect models to calculate odds ratios (OR) or mean differences and the corresponding 95% CI. Bias-factors were assessed with Cochrane risk of bias tool (RoB2). (PROSPERO ID: CRD42021282177). Results: We identified 9 eligible articles, of which 7 (1128 patients) were included in the meta-analysis. The spasticity numerical rating scale (NRS) was significantly higher in the nabiximols group than in the placebo group (OR 2.41 (95% CI 1.39; 4.18)). Secondary outcomes were in accordance with our primary results. At least some concerns were detected in the risk of bias analysis. Conclusion: Our results indicate that nabiximols is efficient in MS associated spasticity, refractory to standard treatment and it may be considered as add-on symptomatic therapy. Nevertheless, further studies are needed to establish the optimal treatment protocol – dose, duration, moment of initiation, disease type.