Clinical implications of serum IgG₄ levels in patients with IgG₄-related ophthalmic disease

The present study aimed to investigate the clinical implications of serum IgG₄ levels in patients with IgG₄-related ophthalmic disease (ROD).

The medical records of 31 patients who met the diagnostic criteria for IgG₄-ROD were retrospectively reviewed. Twenty-five patients whose serum IgG₄ levels could be identified were included. Clinical manifestations and serum IgG₄ levels before and after corticosteroid treatment were obtained. Factors associated with relapse were evaluated by comparing the features of patients with disease relapse with those of patients without relapse.

Twenty-four patients were 'definite' and one was 'probable' for IgG₄-ROD according to the diagnostic criteria. Serum IgG₄ levels were higher in patients with systemic involvement (p=0.046). All patients improved clinically after corticosteroid treatment. Serum IgG₄ levels decreased after steroid treatment (p=0.005) and normalised in nine patients. In cases of relapse, serum IgG₄ levels increased along with the aggravation of symptoms (p=0.047). Serum IgG₄ levels that were still elevated (≥135 mg/dL) after steroid treatment (p=0.034) and cessation of steroid treatment during disease remission (p=0.043) were predictive factors for IgG₄-ROD relapse.

Serum IgG₄ level can be considered an adjunctive marker for treatment response in IgG₄-ROD. Patients with serum IgG₄ levels that remain elevated after steroid treatment should be carefully observed for relapse. A continuing maintenance dose of oral steroid is recommended to prevent relapse, even when clinical remission is achieved.