Relapse and infection scores may help decide whether to extend rituximab in ANCA vasculitis

Design

External validation of prediction models in pooled trial cohorts

Population

217 patients with ANCA-associated vasculitis after 18 months of rituximab (MAINRITSAN 1 and 2)

Primary outcome

Relapse-free and serious infection-free survival

Effect

72-month relapse-free survival 55%; infection model HR 2.93 (95% CI 1.28–6.72); relapse model HR 1.91 (0.97–3.76)

Rituximab maintenance for 18 months reduces relapse in ANCA-associated vasculitis, and some patients benefit from longer treatment, but longer immunosuppression raises infection risk. This study tested two published prediction models in 217 patients from the MAINRITSAN 1 and 2 trials, followed to the end of 2020.

By 72 months, 45% had relapsed and 20% had a serious infection. The relapse model, using male sex, age over 60, ANCA positivity, relapsing disease, ENT involvement and prednisone dose, predicted major relapse, especially in PR3-ANCA disease, although the separation of high- and low-risk groups did not quite reach significance. The infection model, using male sex, structural lung disease, diabetes, infections during maintenance and immunoglobulin level, identified a high-risk group with about three times the rate of serious infection (HR 2.93).

These are external validations in a trial population, not trials of using the scores to decide treatment. But they put structure on a decision that is often made by instinct: a PR3-positive patient with ENT disease and no infection history is a different case from a man with diabetes, bronchiectasis and low IgG. It was published on 28 September 2026.

• Before stopping rituximab at 18 months, weigh relapse risk: the model used male sex, age over 60, ANCA positivity, relapsing disease, ENT involvement and prednisone dose, and its score was associated with relapse risk mainly within the PR3-ANCA subgroup.
• Weigh infection risk as well: structural lung disease, diabetes, prior infections and low immunoglobulins weigh against extending.
• Discuss both risks with the patient and record the reasoning.
• Check immunoglobulin levels before deciding on extension.
• Reassess the decision if infections occur during extended treatment.

Why it matters

It turns the extend-or-stop decision into an explicit balance of two measurable risks.

Don't overread it

The models were validated for prediction; no trial has yet shown that using them improves outcomes.

The statistics, in plain English

A hazard ratio of 2.93 (95% CI 1.28–6.72) for the infection model means high-risk patients had about three times the rate of serious infection; the wide interval reflects only 33 infections. The relapse model's hazard ratio of 1.91 had an interval (0.97–3.76) just crossing 1, so its separation of risk groups is less certain.

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