Self-Reported Allergies in IgG4-Related Disease: A Case-Control Study

Abstract

Objective: IgG4-related disease (IgG4-RD) is an immune-mediated condition of unknown etiology. There has been controversy over the significance of allergic conditions in IgG4-RD. We examined the prevalence of allergy symptoms in IgG4-RD and the association between allergy symptoms and IgG4-RD in a case-control study. Methods: We identified IgG4-RD patients and non-IgG4-RD controls seen at a single center. IgG4-RD patients were classified using the ACR/EULAR classification criteria. Allergy symptoms were ascertained by questionnaire. We assessed the association of IgG4-RD features (e.g., age of onset, organ involvement) with self-reported allergy symptoms. We compared the proportion of cases and controls with allergic symptoms using conditional logistic regression to estimate odds ratios and 95% confidence intervals after matching cases and controls 1:1 by age and sex. Results: Allergic symptoms were reported by 165 (71%) of 231 IgG4-RD cases who completed the questionnaire. Compared to those without allergies, IgG4-RD cases with allergies were more likely to have head and neck involvement (adjusted odds ratio 2.0 [95% CI: 1.1-3.6]) and more likely to have peripheral eosinophilia (adjusted odds ratio 3.3 [95% CI: 1.2-9.0]). The prevalence of allergic symptoms among IgG4-RD cases was not different from that of the controls with other rheumatic conditions (110 [72%] vs. 114 [75%], OR 0.9 [95% CI: 0.5-1.5]). Discussion: Allergic symptoms are common in IgG4-RD but are reported with a similar frequency by patients with IgG4-RD and patients with other rheumatic conditions. These findings suggest that allergic conditions are not uniquely linked to the pathogenesis of IgG4-RD.