Rituximab and belimumab reached low lupus activity at similar rates in a single-centre registry

Design

Prospective single-centre observational cohort with propensity-score weighting

Population

176 patients: 175 rituximab courses and 58 belimumab courses in lupus

Primary outcome

Low disease activity (SLEDAI-2K 4 or less with prednisolone 5 mg/day or less)

Effect

Cox HR 0.92 (95% CI 0.57 to 1.48); overlap-weighted HR 0.86 (0.54 to 1.37)

This prospective single-centre observational study used a lupus registry to compare treatment courses of rituximab (175 courses in 148 patients) and belimumab (58 courses in 58 patients) started between 2011 and 2025. Patients who switched or entered trials were excluded. The primary outcome was low disease activity, meaning SLEDAI-2K of 4 or less with prednisolone of 5 mg a day or less.

Belimumab patients began with higher disease activity (SLEDAI-2K 12.4 against 9.5) and had shorter follow-up (median 2.0 against 3.4 years). In adjusted analyses, low disease activity was similar: hazard ratio 0.92 (95% CI 0.57 to 1.48) in the Cox model and 0.86 (0.54 to 1.37) with propensity-score overlap weighting. Drug survival was similar when used first line, but among second-line users belimumab showed higher survival (HR 1.34, 95% CI 1.03 to 1.77).

Channelling of sicker patients to one drug, small numbers of belimumab courses and a single centre limit the comparison. The finding of similarity is reassuring about practice but does not establish equivalence.

• Low disease activity was similar: adjusted HR 0.92 (95% CI 0.57 to 1.48).
• Belimumab patients started with higher disease activity.
• Second-line drug survival was higher with belimumab (HR 1.34, 1.03 to 1.77).
• Only 58 belimumab courses were included.
• Choice is guided by organ involvement, guidelines, access and cost.

Why it matters

Head-to-head evidence between these two drugs is scarce and clinicians have to choose without it.

Don't overread it

An observational comparison with different baseline severity and follow-up cannot show equivalence.

The statistics, in plain English

A hazard ratio of 0.92 with an interval from 0.57 to 1.48 is compatible with anything from a large advantage to a modest disadvantage for belimumab, so 'no difference' mainly means the study was too small to decide.

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