Ofatumumab was linked to slightly more relapses than ocrelizumab, but both rates were very low

Design

Nationwide registry cohort with propensity score weighting

Population

1,870 adults with relapsing-remitting MS in Denmark

Primary outcome

Annualised relapse rate

Effect

0.05 vs 0.03; rate ratio 1.65 (95% CI 1.09 to 2.50)

The Danish Multiple Sclerosis Registry compared 1,385 patients with relapsing-remitting MS who started ofatumumab with 485 who started ocrelizumab between 2022 and 2025, using propensity weighting to balance baseline differences.

The annualised relapse rate was 0.05 with ofatumumab and 0.03 with ocrelizumab (rate ratio 1.65, 95% CI 1.09 to 2.50). Time to first relapse (HR 1.50, 0.99 to 2.29), confirmed disability worsening, progression independent of relapse and MRI activity did not differ significantly. Follow-up was a median of about two years.

The absolute difference is about one extra relapse every 50 patient-years. Patients choosing between a monthly self-injected drug and a six-monthly infusion can weigh convenience against this small, observational difference.

• Both anti-CD20 therapies gave very low relapse rates in routine practice
• Ofatumumab was associated with about one extra relapse per 50 patient-years versus ocrelizumab
• No difference was seen in disability worsening or progression independent of relapse
• Let route, monitoring and patient preference guide the choice between them

Why it matters

It is the largest head-to-head real-world comparison of the two anti-CD20 drugs most often chosen between.

Don't overread it

This is observational; residual confounding by indication may explain the difference.

The statistics, in plain English

A rate ratio of 1.65 sounds large, but on base rates of 0.03 and 0.05 relapses a year the absolute gap is tiny. Propensity weighting cannot remove unmeasured reasons why a neurologist chose one drug over the other.

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