Acute Kidney Injury in Inflammatory Bowel Disease Patients: A Nationwide Comparative Analysis.

Rationale & Objective: About 25%-40% of patients with inflammatory bowel disease (IBD) may have extraintestinal manifestations, mainly involving the liver, skin, and joints. Kidney involvement in patients with IBD has been reported, but there are no estimates of its prevalence in population-based studies in the United States. We compared the frequency of acute kidney injury (AKI) among hospitalizations with IBD with that among hospitalizations with collagen vascular diseases and hospitalizations with neither condition. Study Design: Retrospective, population-based cohort study. Setting & Participants: Healthcare Cost and Utilization Project-Nationwide Inpatient Sample database. Outcomes: AKI and AKI requiring dialysis. Analytical Approach: Regression models were used to compare the occurrence of AKI among groups. Inverse probability of treatment weighting was applied to balance groups on covariates. Results: The final sample comprised 5,735,804 hospitalizations, including 57,121 with IBD, 159,930 with collagen vascular diseases, and 5,518,753 with neither IBD nor collagen vascular diseases. AKI was observed in 13%, 15%, and 12.2% of hospitalizations with IBD, collagen vascular diseases, and the general population, respectively. When adjusting for demographic, hospital, and clinical characteristics using inverse probability of treatment weighting, hospitalizations with IBD had higher odds of being diagnosed with AKI than both those with collagen vascular diseases (odds ratio [OR], 1.32; 95% confidence interval [CI], 1.27-1.38) and the general population (OR, 1.27; 95% CI, 1.23-1.31) and also had higher odds of being diagnosed with AKI requiring dialysis than those with collagen vascular diseases (OR, 1.59; 95% CI, 1.31-1.94) or than the general population (OR, 1.45; 95% CI, 1.25-1.68). Limitations: Cross-sectional analysis, underreporting of International Classification of Diseases codes, and analyses relevant to in-hospital stays only. Conclusions: The prevalence and risk of AKI among hospitalizations with IBD is greater than that of hospitalizations with collagen vascular diseases and the general population. Coexisting kidney disease should be considered among patients with a known diagnosis of IBD.