S848 Incidence of Pneumonia, Related Hospitalization, and Mortality Among Younger Unvaccinated IBD Patients in a Veteran Affairs Cohort

Abstract

Introduction: Community Acquired Pneumonia (CAP) is a serious infection among Inflammatory Bowel Disease (IBD) patients for whose prevention pneumococcal vaccination is recommended. While in the general population vaccination is recommended at age 65, among IBD patients it is recommended at a younger age especially among those exposed to immunosuppressive agents. Our study aimed to determine incidence of CAP, related hospitalization, and mortality among unvaccinated IBD population younger than 65 years and compare the rates between those exposed to immunosuppressive medications and those who were not. Methods: We conducted a retrospective cohort study utilizing a nationwide cohort of IBD patients who were younger than 65 years of age in the Veterans Affairs Healthcare System (VAHS). Exposure was administration of any immunosuppressive medication for IBD management. Patients were considered exposed on the first date of immunosuppressive medication. For the unexposed group the starting time was the instance of the first 5-ASA medication. The primary outcome was the first occurrence of pneumonia; secondary outcomes being pneumonia related hospitalization and mortality. Patients who had pneumonia confirmed based on CXR findings and individual chart review were included. Results: Among a total of 26,707 patients, 513 patients developed pneumonia. Mean age in years (SD) was 51.67 (11.34) for the exposed and 45.91 (12.34) for the unexposed group. (Table) The overall crude incidence rate was 3.2 per 1000 patient-years (4.04/1000 patient years in the exposed vs 1.45/1000 patient-years in the unexposed). The crude incidence rates for pneumonia related hospitalization for all the patients, the exposed, and the unexposed were 1.12, 1.44, and 0.44 per 1000 patient-years, respectively. The crude incidence rates for pneumonia-related death for all the patients, the exposed, and the unexposed were 0.09, 0.11, and 0.06 per 1000 patient-years, respectively. In Cox regression, exposed group was associated with an increased risk of pneumonia (AHR 2.85; 95% CI 2.21 – 3.66, p < 0.001) and pneumonia-related-hospitalization (AHR 3.46; 95% CI 2.20 – 5.43, p < 0.001). (Figure) Conclusion: Among younger unvaccinated IBD patients, incidence as well as the risk of pneumonia and related hospitalization were higher among those exposed to immunosuppressive medications. These findings will help guide physicians and patients to make informed decisions about vaccination.Figure 1.: Effect of intake/administration of any immunosuppressive medication(s) on incidence of pneumonia Table 1. - Characteristics and outcome of patients by exposure Exposed (N = 17727) Not exposed (N = 8980) P-value Age (mean ± SD) 51.67 ± 11.34 45.91 ± 12.34 < 0.001 Gender Male 15625 (88) 8262 (92) < 0.001 Female 2102 (12) 718 (8) Race White 13987 (79) 7294 (81) < 0.001 Black 2492 (14) 939 (10) Other 389 (2) 202 (2) Unknown 859 (5) 545 (6) Geographic locations Continental 2972 (17) 1387 (15) < 0.001 Midwest 3901 (22) 2059 (23) North Atlantic 4101 (23) 2330 (26) Pacific 3257 (18) 1550 (17) Southeast 3496 (20) 1654 (18) IBD type CD 8563 (48) 2831 (32) < 0.001 UC 9164 (52) 6149 (68) CCI (mean ± SD) 0.49 ± 1.06 0.52 ± 1.17 0.129 Smoking status Yes 7247 (41) 4260 (47) < 0.001 No 10480 (59) 4720 (53) Chronic Pulmonary Disease Yes 1785 (10) 554 (6) < 0.001 No 15942 (90) 8426 (94)