The following is a summary of “Trimethoprim sulfamethoxazole prophylaxis and serious infections in granulomatosis with polyangiitis treated with rituximab,” published in the July 2024 issue of Rheumatology by Mendel et al.

Researchers conducted a retrospective study evaluating how trimethoprim-sulfamethoxazole (TMP-SMX) prophylaxis affects the incidence of serious infections in rituximab-treated patients with granulomatosis with polyangiitis (GPA).

They utilized the United States Merative^TM Marketscan^® Research Databases to include adults with GPA (2011 to 2020), with at least 6 months of enrollment before the first rituximab treatment. The TMP-SMX prophylaxis was defined as a 28-day prescription after or overlapping the index date. Serious infections were identified as hospital primary diagnoses for infection (excluding viral or mycobacterial). Secondary outcomes included outpatient infections, Pneumocystis jirovecii pneumonia (PJP), and AEs related to TMP-SMX. Cox proportional hazards regression analyzed the association of TMP-SMX with the outcomes, adjusting for confounders, with follow-up ending at the outcome, database enrollment end, or December 31, 2020.

The result showed 919 individuals treated with rituximab (53% female), the mean age was 52.1 years (SD 16), and 281 (31%) received TMP-SMX within 30 days of the index date. In a follow-up of 496 days (IQR 138, 979),  104 individuals had 130 serious infections, resulting in an incidence rate of 6.1 (95% CI 5.0–7.4) per 100 person-years. The TMP-SMX was found to be negatively associated with serious infections (aHR 0.5; 95% CI 0.3–0.9). For outpatient infections, the aHR was 0.8 (95% CI 0.6–1.1), while the estimate for PJP was less precise (13 events, unadjusted HR 0.2; 95% CI 0.03–1.8). The TMP-SMX was potentially linked to AEs (aHR 1.3; 95% CI 0.9–1.9).

Investigators concluded that while TMP-SMX prophylaxis reduced serious infections in rituximab-treated GPA, it may increase AEs, highlighting the need for further research on the best prophylaxis strategies.

Source: academic.oup.com/rheumatology/advance-article/doi/10.1093/rheumatology/keae368/7716551