Rituximab seems well tolerated in patients with rheumatoid arthritis (RA). However, variations in the gammaglobulin profile that might increase the infection risk have been reported. Here, our objective was to evaluate gammaglobulin concentrations and the infection risk in patients receiving rituximab therapy for RA in everyday practice.

Prospective single-center observational study of 65 patients with refractory RA (median age, 59 years; range, 26–83) treated with rituximab 1g twice 15 days apart, with or without a further 1-g dose at least 6 months later depending on the clinical response. Gammaglobulins were assayed before each rituximab dose.

The median cumulative rituximab dose was 4g (1–16) and the median time to retreatment was 8 months (6–16). Rituximab therapy significantly improved the DAS-28 score. The gammaglobulin concentration decreased significantly between the first and last rituximab dose (from 11.6g/L [5–26] to 8.2g/L [3–20], a −2.6g/L difference; P<0.05). The decrease was larger in the 24 patients with cumulative rituximab doses greater than 5g than in the 41 other patients (difference of −4 vs −2.7g/L; P<0.05). Three patients experienced severe infections, two in the high-dose group and one in the other group (P=0.5).

These data obtained in everyday practice constitute further evidence that rituximab is well-tolerated in patients with RA. Rituximab therapy was associated with a decrease in gammaglobulin concentrations that was greater in patients receiving higher cumulative doses.