LAUSR

We thank Dr Wallace et al for their response to our recently published article ‘Trimethoprim–sulfamethoxazole prophylaxis prevents severe/life-threatening infections following rituximab in antineutrophil cytoplasm antibody-associated vasculitis’, highlighting some methodological limitations of our study.1 2 One of the limitations mentioned by Wallace and colleagues is the inclusion of incident and prevalent cases and since only 15 out of 192 patients were incident cases, generalisability of our findings for this subset of patients may not be possible. We agree that the use of immunosuppression prior to initiation of rituximab likely confers a risk to develop infectious complications after rituximab administration. Cyclophosphamide was used to control disease in 62 patients the year before rituximab was initiated. Among these, 53 patients had no severe infection (median cyclophosphamide exposure 7 g, range 0.66–45 g), while 9 patients receiving cyclophosphamide the index year before had a severe infection following rituximab (median cyclophosphamide exposure 4.8 g, range 0.8–10 g). While this argues against an immediate impact of cyclophosphamide before rituximab on the risk of severe infections (53/143 with no severe infection against 9/49 with infection received …