Secondary systemic amyloidosis in inflammatory bowel disease: a nationwide analysis.

Background: Secondary systemic amyloidosis (SSA) is a rare but severe complication of inflammatory bowel disease (IBD). We aimed to evaluate the clinical characteristics, predictors of complications, and in-hospital mortality of patients with Crohn's disease (CD) and Ulcerative colitis (UC) who develop SSA.

Methods: Using the National Inpatient Sample, we identified patients hospitalized for IBD and SSA between 2004 and 2012. Using multivariate logistic regression, patients with CD were compared with those with UC regarding the presence or absence of SSA. IBD patients without SSA were matched in a 2:1 ratio with those with SSA using propensity matching. We analyzed the hospitalization trends of SSA in CD and UC patients using Pearson's χ test. Analyses were performed using SAS version 9.3.

Results: Among the 302,548 patients with CD and 174,057 patients with UC hospitalized between 2004 and 2012, we identified 47 (0.02%) and 36 (0.02%) cases of SSA, respectively. We noted rising annual hospitalization trends for both CD and UC patients with or without SSA. In-hospital mortality was significantly higher for both the UC+SSA group (16.7% vs. 2.1%, P<0.0001) and the CD+SSA group (6.4% vs. 1.0%, P=0.0001) before propensity matching. However, this difference was not seen for either UC+SSA (17.1% vs. 7.1%, P=0.11) or CD+SSA (6.8% vs. 2.3%, P=0.20) after matching.

Conclusions: SSA rarely affects IBD patients, but when it does, it is associated with increased rates of infection, severe sepsis, and multi-organ system involvement. Despite this, SSA does not affect in-hospital mortality in IBD patients. Further studies are needed to explore this association.