IGHE and allergic disease: To date, our study is the largest cohort evaluating the relationship between serum IgE and a history of allergy in IgG4-RD patients, and we found that group B had more patients with allergy disease than group A. Our study also showed that group B had more organ involvement and higher IgG4-RD RI scores than group A, indicating that patients with high baseline IgE levels might have higher disease activity.