Study details
To look at the characteristics of and risk factors for serious infections associated with rituximab use in AAV, Mr. Dernie and associates retrospectively examined the electronic records of patients who had been treated between August 2016 and August 2019. Follow-up was until August 2020.
Of the 50 patients identified, nearly half (48%) were men. The average age was 60 years, ranging from 25 to 90 years. Most (n = 36; 72%) patients had a diagnosis of granulomatosis with polyangiitis, while another 2 (4%) had microscopic polyangiitis, 1 (2%) had eosinophilic granulomatosis with polyangiitis, and 11 (22%) had an overlapping type of vasculitis or undefined AAV.
Of the 18 severe infection events recorded, most (56%) involved the respiratory tract. Less than one-third (28%) were sepsis or neutropenic sepsis events, and there was one case each (6%) of cellulitis, complicated urinary tract infection, and recurrent wound infection.
There were “small numbers of individual comorbidities that were not sufficient to enter into our regression analysis,” Mr. Dernie noted. “It’s likely that comorbid conditions such as COPD [chronic obstructive pulmonary disease] also contribute to an individual’s risk of developing severe infections, and thus should factor into their individualized management.”
Mr. Dernie acknowledged in discussion: “One of the limitations of the study was we just looked at patients in a time when they were receiving rituximab, so they may have historically been exposed to other treatment options.” However, he added, “they weren’t having any other major DMARDs or immunosuppressive treatments at the time.”
Dr. Luqmani observed: “If you look at Francesco’s data on the hypogammaglobulinemia at the start of rituximab, that probably gives you a good idea of just how immunosuppressed these patients were already before we got to this point.”
Dr. Luqmani added: “I suspect that’s in keeping with a lot of other centers that have started using rituximab an awful lot for patients who previously had episodes of vasculitis treated with other disease-modifying therapies, particularly cyclophosphamide.”
But for how long should co-trimoxazole be given after the last rituximab dose? asked the chair of the session, Richard Watts, DM, of Norwich (England) Medical School. These data are purely observational, so it’s not possible to say, Mr. Dernie noted: “The patients that we included as having co-trimoxazole seem to be on it more or less consistently, permanently,” he said.
What about the best dose? “It’s a tricky one,” Dr. Luqmani said, as “we not only use co-trimoxazole for prophylaxis, but we often also want to use it for treatment of the vasculitis itself.”
It’s very likely that there was a mix of patients in the analysis that had received co-trimoxazole as either a treatment or prophylaxis, which means different doses, he said.
“It might be interesting to know whether there was a difference” between doses used and the prevention of infection, added Dr. Luqmani, “but I suspect the numbers are too small to tell.”
Mr. Dernie, Dr. Luqmani, and the other coauthors had no disclosures.