The serious infection risk associated with rituximab treatment for antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) is high but can be offset by co-prescribing co-trimoxazole, data from a single-center, retrospective study reaffirm.
Over the course of a 3-year study period, 14 (28%) of 50 patients with AAV treated with rituximab experienced at latest one severe infection defined as a grade 3 or higher event. The incidence of severe infections was 15.4 per 100 person-years.
However, a lower rate of infections was seen in patients who had been co-prescribed co-trimoxazole (trimethoprim and sulfamethoxazole), Francesco Dernie, a fifth-year medical student at the University of Oxford (England), reported at the British Society for Rheumatology annual conference.
“In the case of rituximab, the depletion of B cells and associated immune suppression is a double-edged sword, allowing effective disease control, but also leaving the body vulnerable to opportunistic and severe infections,” Mr. Dernie said at the meeting.
Of the patients who developed a severe infection on rituximab, just 7% had been treated with co-trimoxazole. In comparison, 44% of those who did not get a severe infection had received co-trimoxazole. Multivariate analysis confirmed that co-trimoxazole use was an influencing factor, with an odds ratio (OR) of 0.096 (95% confidence interval, 0.009–0.996; P = .05).
Another finding was that patients with low immunoglobulin G levels (less than 6 g/L) were more likely to develop a severe infection than were those with higher IgG levels. Indeed, the OR for hypogammaglobulinemia and the risk for infection was 8.782 (95% CI, 1.19–64.6; P = .033).
“Our results support the monitoring of IgG levels to identify patients who may be more susceptible to infection, as well as the prescription of prophylactic co-trimoxazole to reduce overall severe infection risk,” Mr. Dernie and associates concluded in their abstract.
It’s a “really important message around co-trimoxazole,” observed Neil Basu, MBChB, a clinical senior lecturer and honorary consultant at the Institute of Infection, Immunity & Inflammation, University of Glasgow (Scotland).
“It still frustrates me when I see that patients haven’t received that while receiving rituximab. Of course, co-trimoxazole can have its problems,” said Dr. Basu, who was not involved in the study. “It’s not uncommon for patients to develop reactions or be intolerant to the drug.”
Raashid Luqmani, DM, a senior coauthor of the work and professor of rheumatology at the Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Science, University of Oxford, said: “The tolerance of co-trimoxazole has been remarkably good in this cohort.” If there was a problem with using co-trimoxazole, then “our standard would be to go with trimethoprim alone as the next in line and follow that with inhaled pentamidine. So, it’s kind of following what we would all generally do,” Dr. Luqmani said.
Dr. Raashid Luqmani
These data add further support for coprescribing antibiotic treatment with rituximab, he suggested.
“Worry about infection, worry about it a lot; not just worry about it, do something about it,” Dr. Luqmani said, and co-trimoxazole “is probably an effective means to do something about it.”