Chemoprophylaxis against Pneumocystis jirovecii pneumonia in Japanese patients with ANCA-associated vasculitis: An observational study

Objectives: This study investigated the current practice of prophylactic treatment against Pneumocystis jirovecii pneumonia (PCP) and its effectiveness in patients with anti-neutrophil cytoplasmic antibody-associated vasculitis (AAV). Methods: This study included 319 patients registered from 53 institutions in Japan and newly diagnosed with AAV. During the 2-year observation period, we examined the frequency of usage, effectiveness and safety of prophylactic drugs against PCP. Results: Most patients received prophylactic drugs against PCP with the initiation of immunosuppressive agents, and >50% of them remained on chemoprophylaxis against PCP at 2 years after. The initial daily dose of oral prednisolone and the proportion of cyclophosphamide administration were higher in patients who received chemoprophylaxis against PCP than in those who did not. PCP occurred in nine patients (3%) and resulted in the death of four. The incidence rate of PCP in patients who received chemoprophylaxis was 1.13/100 patient-years (95% confidence interval, 0.38–2.68) and that in those who did not was 2.74 (1.04–6.02). The incidence rate ratio was 0.41 (0.11–1.53). Conclusions: The markedly low incidence of PCP may be attributed to the continuous chemoprophylaxis against PCP received by >50% of Japanese patients with AAV, although the effectiveness of chemoprophylaxis against PCP was not statistically confirmed.