Background/Purpose: Pneumocystis Jirovecii pneumonia (PJP) is a life-threatening complication in granulomatosis with polyangiitis (GPA). Guidelines from EULAR for ANCA-associated vasculitis (AAV) recommend institution of PJP chemoprophylaxis during cyclophosphamide therapy. Rituximab has been increasingly used in AAV, however the necessity for PJP chemoprophylaxis in this group of patients is unclear. The objective of this study was to determine the incidence and risk of PJP in GPA patients who received Rituximab.

Methods: We conducted a retrospective cohort study using the 2006 to 2013 Truven Health Analytics MarketScan Commercial Claims database which contains inpatient, outpatient, and pharmacy claims from the privately-insured US population. We selected patients aged 2-60 years old and identified GPA and PJP cases using ICD-9-CM codes 466.4 and 136.3, respectively. As GPA shares the same ICD-9-CM code with eosinophilic granulomatosis with polyangiitis, patients with eosinophilia (ICD-9-CM 288.3) were excluded. From these patient records, we collected demographic data, dates of first coding for GPA, presence of PJP and dates of PJP onset, dates of Rituximab use, presence and dates of PJP chemoprophylaxis, and use of immunosuppressive drugs within 90 days of PJP onset. We performed all statistical analyses using STATA (STATA Corp, College Station, TX).

Results: We identified 4,606 patients with GPA. Only 7% of GPA cases (n=322) were children under 21 years of age. The mean age at the time of first coding for GPA was 44.5 ± 12.6 years and 54.5% were female. Less than a quarter of GPA patients received Rituximab chemotherapy during the study period (n=636 patients, 13.8 %). During the study period, 23 GPA patients (0.5%) were diagnosed with PJP. The mean age at PJP onset was 47± 13 years with slight female preponderance (65%). The annual incidence rate of PJP in GPA patients across all ages, regardless of treatment, was 2 cases per 1,000 person-years. Two of the PJP patients were diagnosed with PJP within 2 months of Rituximab initiation, resulting in an annual incidence rate of PJP in Rituximab-treated GPA patients of 1 case per 1,000 person-years. The relative risk of PJP in Rituximab-treated patients was 0.6 (95% CI 0.14-2.53, p=0.48) compared to non-Rituximab-treated patients. Among the 636 patients who received Rituximab, 339 patients (53%) had claims for PJP chemoprophylaxis within 90 days prior to the PJP onset; only one of these developed PJP while on the PJP prophylaxis. The relative risk of developing PJP on prophylaxis medication was 1.0 (95% CI 0.99-1.01, p=0.9).

Conclusion: The overall incidence of PJP in GPA patients and in Rituximab-treated GPA patients in particular, was low. Rituximab does not appear to be associated with an increased risk of PJP in GPA patients. Chemoprophylaxis for PJP may not be indicated in the Rituximab-treated GPA patients. Further study is warranted to evaluate cost-effectiveness of PJP chemoprophylaxis in Rituximab-treated GPA population.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/incidence-and-risk-of-pneumocystis-jirovecii-pneumonia-following-rituximab-treatment-in-granulomatosis-with-polyangiitis-in-the-united-states-an-analysis-from-a-national-database/