The aim of this study was to investigate the role of serum IgE levels in the clinical features and outcomes of IgG4-related disease (IgG4-RD).
We retrospectively enrolled 459 newly diagnosed IgG4-RD patients with serum IgE examined at baseline from 2012 to 2019 and compared the clinical features between group A (serum IgE level ≤ 60 KU/L) and group B (serum IgE level > 60 KU/L). Subsequently, 312 patients who had been followed up for ≥ 1 year were further selected to evaluate the correlation between serum IgE level and disease outcome.
At baseline, the serum IgE level was positively correlated with the serum IgG4 level (r = 0.1779, P = 0.0001), eosinophil count (r = 0.3004, P < 0.0001), and serum IgG level (r = 0.2189, P < 0.0001) in IgG4-RD patients. Compared with group A, group B had more patients with allergic diseases (P = 0.004), more organ involvement (P = 0.003), and higher IgG4-RD responder index scores (P = 0.002). During follow-up, group A patients had a higher remission induction rate than group B patients (88.4% vs. 73.6%, P = 0.035), while group B patients had a higher relapse rate than group A patients (29.0% vs. 16.2%, P = 0.039). Multivariate analysis found that a serum IgE level > 125 KU/L at baseline was a risk factor for disease relapse (hazard ratio [HR], 1.894 [95% confidence interval (CI) 1.022-3.508]; P = 0.042). Cox regression analysis showed that elevation of the eosinophil count was a risk factor for relapse in both group A and group B patients (HR, 8.504 [95% CI 1.071-42.511]; P = 0.009; and HR, 2.078 [95% CI 1.277-3.380]; P = 0.003, respectively), and the involvement of the lacrimal gland (HR, 1.756 [95% CI 1.108-2.782]; P = 0.017), submandibular gland (HR, 1.654 [95% CI 1.037-2.639]; P = 0.035), and kidney (HR, 3.413 [95% CI 1.076-10.831]; P = 0.037) were also risk factors for relapse in group B patients.
IgG4-RD patients with high serum IgE levels at baseline were more likely to have higher disease activity, and baseline high IgE levels were associated with disease relapse.