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

Design

Nationwide registry cohort, propensity-weighted, intention to treat

Population

1,870 people with relapsing-remitting MS starting ofatumumab or ocrelizumab, Denmark

Primary outcome

Annualised relapse rate and time to first relapse

Effect

ARR 0.05 vs 0.03, rate ratio 1.65 (1.09–2.50); time to relapse HR 1.50 (0.99–2.29)

This Danish nationwide registry study compared 1,385 people with relapsing-remitting MS starting ofatumumab with 485 starting ocrelizumab between 2022 and 2025, using propensity weighting to balance baseline differences. Median follow-up was 2.0 and 2.5 years.

The annualised relapse rate was 0.05 with ofatumumab and 0.03 with ocrelizumab, a rate ratio of 1.65 (95% CI 1.09–2.50). Time to first relapse, confirmed disability worsening at 24 weeks, progression independent of relapse activity and MRI lesion activity did not differ significantly, although the MRI estimate leaned the same way (HR 1.72, 0.95–3.13). Per-protocol results agreed.

In absolute terms the gap is about one extra relapse for every 50 patient-years. The authors themselves call it of limited clinical relevance, and residual confounding by indication is likely, because the choice between a monthly self-injection and a six-monthly infusion is rarely random. Both remain highly effective options; the practical choice can rest on route, monitoring, pregnancy plans and access.

• Both anti-CD20 drugs produced very low relapse rates, at or below one relapse per 20 patient-years.
• The difference amounted to about one extra relapse per 50 patient-years with ofatumumab.
• Disability worsening and progression independent of relapse did not differ.
• Base the choice on route, monitoring burden, pregnancy plans, infection risk and access.

Why it matters

Real-world data suggest a small relapse gap between the two anti-CD20 options, too small to drive the choice on its own.

Don't overread it

This was observational, and patients choosing a self-injection may differ from those choosing infusions in ways weighting cannot remove.

The statistics, in plain English

A rate ratio of 1.65 sounds large, but applied to very low baseline rates it is a small absolute difference. The confidence interval for disability outcomes crosses 1, so no difference there can be claimed either way.

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