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

OBJECTIVES: 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. CONCLUSIONS: 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.