Impact of Low Immunoglobulin G Levels on Disease Outcomes in Patients with Inflammatory Bowel Diseases.

Abstract

Inflammatory bowel diseases (IBDs) are considered immune-mediated disorders with dysregulated innate and adaptive immunities. Secondary immunogloblin deficiency can occur in IBD and its impact on the disease course of IBD is not clear. We sought to determine associations between low IgG/G1 levels and poor clinical outcomes in IBD patients. This historic cohort study was performed on IBD patients with obtained IgG/IgG1 levels. The primary outcome was defined as any IBD-related bowel resection surgery and/or hospitalization. Subgroup analyses assessed particular surgical outcomes in Crohn's disease (CD), ulcerative colitis (UC) or indeterminate colitis (IC), and ileal pouch-anal anastomosis (IPAA). The secondary outcomes included IBD drug escalations and C. difficile or cytomegalovirus infections. A total of 136 IBD patients had IgG/G1 levels checked and adequate follow-up, 58 (42.6%) with normal IgG/G1 levels and 78 (57.4%) having low levels. A total of 49 patients (62.8%) with low immunoglobulin levels had IBD-related surgeries or hospitalizations, compared to 33 patients (56.9%) with normal levels [odds ratio (OR) 1.28, 95% confidence interval (CI) 0.64-2.56; p=0.49]. Low IgG/G1 levels were associated with IBD-related surgery in CD in univariate analysis [hazard ratio (HR) 4.42, 95% CI 1.02-19.23; p=0.048] and in Kaplan-Meier survival curve analysis (p=0.03), with a trend toward significance on multivariate analysis (HR 3.07, 95% CI 0.67-14.31; p=0.15). IBD patients with low IgG/G1 levels required more small bowel resections (12.8 vs. 1.7%, p=0.024) and 5-aminosalicylate initiations (28.2 vs. 13.8%, p=0.045). Our study demonstrated a possible association between low IgG/G1 levels and poor outcomes in CD including surgery. Future implications include using immunoglobulin levels in IBD patients as a prognostic indicator or boosting humoral immunity as a treatment in this subset.