Risk factors of relapse following glucocorticoid tapering in IgG4-related disease

Objective. To identify risk factors of relapse in IgG4-related disease (IgG4-RD) during glucocorticoid (GC) tapering. Methods. A total of 27 consecutive patients with IgG4-RD (7 with and 20 without relapse) treated with GC for more than 6 months were enrolled. Baseline characteristics were compared in patients with and without relapse. Longitudinal analysis was also performed. Results. Patients with relapse had significantly higher levels of serum IgG4 (816.0 vs. 346.5 mg/dL, p=0.048) and number of organs involved (5 vs. 3, p=0.008) and lower levels of serum IgA (82 vs. 176 mg/dL, p=0.002) at baseline, compared to patients without relapse. The most useful cut-off value of baseline serum IgG4 to predictive relapse was 813 mg/dl with a sensitivity of 57.1% and a specificity of 95.0%. In longitudinal analysis, serum IgG4 decreased at 6 months after treatment in both groups, but was elevated at relapse in patients with relapse, while remaining low in those without relapse. Conclusion. Higher levels of serum IgG4 at baseline were associated with relapse in IgG4-RD. Re-elevation of serum IgG4 levels during GC treatment reflected disease relapse.