S1481 Beyond the Gut: Risk of Pneumocystis Pneumonia in Veterans With Inflammatory Bowel Disease

Introduction: Pneumocystis jirovecii pneumonia (PJP) is a rare complication seen in severe immunosuppression with mortality as high as 50%. Recommendations for PJP prophylaxis when using immunosuppressants are derived largely from oncologic populations. Whether immunosuppression in patients with inflammatory bowel disease (IBD) needs PJP prophylaxis is unknown, yet guidelines recommend prophylaxis for the most severely immunosuppressed. Here, we aimed to measure the incidence and identify risk factors associated with PJP infection in the Veteran IBD population. Methods: Veterans Health Administration data (2015-2024) was used in this retrospective case-control study to identify IBD patients with and without PJP. Patients with HIV, solid-organ transplant, or receiving active chemotherapy were excluded. Demographic and clinical characteristics were collected from the database along with evaluation of pharmacy records. PJP cases were identified using diagnosis codes and matched 1:4 with non-PJP IBD controls based on age, sex, and IBD type. Medication exposures were evaluated in the 6 months prior to PJP diagnosis (or for controls, the PJP diagnosis date of their associated case), and relevant comorbid diagnoses were evaluated. Results: We identified 101,350 Veterans with IBD. Of these, 13,564 (13.4%) had exposure to immunomodulators, 14,558 (14.4%) had exposure to biologic agents, 36,257 (35.8%) had exposure to systemic steroids, and 12,640 (12.5%) were exposed to systemic steroids in addition to a biologic or immunomodulator; 33 cases of PJP were found. 21/33 were confounded by HIV, transplant, or active chemotherapy and excluded. 12 PJP-IBD cases were included in the final analysis. Compared to non-PJP IBD controls, PJP cases more often were type 2 diabetic (P < .01) and had heart failure (P = .01), malnutrition (P < .01), and opioid use disorder (P = .04). PJP cases were more often on systemic steroids (7/12 vs 4/48 controls, P < .01). 2/12 PJP cases and no non-PJP IBD controls were receiving both steroids and PJP prophylaxis. Conclusion: In this retrospective, large database case-control analysis, despite the majority of patients receiving immunosuppressing therapies without prophylaxis, PJP remained a rare event. Though steroid use was associated with PJP cases, the low rate of PJP is such that utility of prophylaxis is questionable and must be weighed against the cost and potential for side effects. We did not find associations with other or combination IBD therapies and PJP.