To compare Expanded Disability Status Scale (EDSS) and relapse-based outcomes in RRMS patients receiving first-line (1L) natalizumab or 1L injectable therapies (injectables).

Natalizumab is highly efficacious in treating RRMS. Though mostly used as second line, natalizumab used as a 1L therapy could bring additional benefits to patients compared to 1L injectables. This analysis extends and updates current comparative evidence for natalizumab 1L use.

RRMS patients receiving 1L natalizumab or injectables (intramuscular or subcutaneous interferon beta-1a, subcutaneous interferon beta-1b, peginterferon beta-1a or glatiramer acetate) for ≥12 months between 2014 and 2018 were identified from the Adelphi MS Disease Specific Programme™, an international (U.S.A., U.K., Spain, Italy, France and Germany) cross-sectional study of MS patients. Average treatment effects for 1L natalizumab compared to 1L injectables were estimated, after inverse propensity score weighting to create balanced treatment groups. Variables used for weighting at baseline treatment initiation included gender, age, EDSS and time since diagnosis. Outcomes, compared with a Wald test, following regression adjustment for treatment duration, were EDSS change since treatment initiation as well as number and duration of relapses, in the last 12 months.

Data were available for 2307 (137 1L natalizumab, 2170 1L injectables) patients. After covariate adjustment, natalizumab patients were reported to have a significant reduction in relapses of 0.41 (0.27 vs 0.68, p<0.001), a decrease of 3.96 days in the mean duration of last relapse (2.31 vs 6.28, p<0.001), and a 0.34 greater reduction in EDSS score since treatment initiation (-0.62 vs -0.28, p=0.001) compared to injectable patients. Sensitivity analyses did not change any outcome significantly.

This real-world data analysis demonstrates that 1L natalizumab treatment is associated with better disability and relapse-based outcomes compared to injectables. These results extend previous findings that support earlier natalizumab utilization for improved disease control and can assist informed healthcare decision-making.