Comorbidities and systemic steroids drive pneumonia risk in inflammatory bowel disease: Propensity score-matched cohort study.

Background: Patients with inflammatory bowel disease (IBD) are at an increased risk of bacterial pneumonia, contributing to significant morbidity and mortality. While previous studies have identified various risk factors, including medications and comorbidities, the independent contribution of IBD to pneumonia risk remains unclear. We hypothesized that the increased pneumonia risk is primarily driven by factors other than IBD itself.

Aim: To investigate the relative contributions of IBD, comorbidities, and medications to pneumonia risk in patients with IBD.

Methods: We conducted a retrospective cohort study using the All of Us Research Program database (2010-2022). We matched 2810 participants with IBD 1:1 with controls using four propensity score models: (1) Demographics/Lifestyle only; (2) Plus comorbidities; (3) Plus medications; and (4) All factors combined. Then we used Cox proportional hazards models to assess pneumonia risk and logistic regression to evaluate risk factors.

Results: In the primary analysis of 5620 matched participants, IBD was not independently associated with increased pneumonia risk [hazard ratio (HR) = 1.07, 95%CI: 0.84-1.35] when matched for all factors. However, participants with IBD had significantly higher risk (HR = 2.08, 95%CI: 1.56-2.78) when matched only for demographics and lifestyle factors. Within the IBD cohort, a high comorbidity burden (Charlson Comorbidity Index ≥ 10) [odds ratio (OR) = 12.20, 95%CI: 6.69-23.00] and systemic steroid use (OR = 2.26, 95%CI: 1.21-4.64) were independently associated with increased pneumonia risk.

Conclusion: Comorbidities and systemic steroids, rather than IBD itself, drive pneumonia risk. Management should focus on these factors and prioritize vaccination in high-risk patients.