Methotrexate for maintenance of remission in IgG4-related disease: Fig. 1

Sir, IgG4-related disease (IgG4-RD) is a rapidly emerging systemic fibro-inflammatory disorder generally characterized by tumefactive lesions and often by elevated serum IgG4 concentrations [1]. IgG4-RD responds swiftly to high-dose glucocorticoids, but a substantial percentage of patients relapse either during or after glucocorticoid tapers, especially in cases of multi-organ involvement and history of disease relapse [2, 3]. In the present retrospective work we aimed to assess the efficacy of MTX in maintaining long-term glucocorticoid-induced remission by evaluating disease activity through the IgG4-RD Responder Index (IgG4-RD RI) [4], the patient’s ability to taper or stop prednisone, serum IgG4 concentration and radiological outcomes. Ten patients with active biopsy-proven IgG4-RD were referred to our centre for IgG4-RD and were followed up between January 2008 and September 2014 (supplementary Table S1, available at Rheumatology Online) [5]. All patients provided written informed consent for the analyses and treatments described in the study. In six patients IgG4-RD relapsed on average 6 months (range 2–9) after the institution of glucocorticoid treatment, at a mean glucocorticoid daily dose of 9.6 mg (range 0–20). Three patients were also on CYC or AZA (supplementary Table S1, available at Rheumatology Online). The mean IgG4-RD RI at baseline was 8.5 (range 3–15). Six patients had elevated serum IgG4 concentrations (mean 1292 mg/dl, range 155–3700). Disease response was defined as a decline in the IgG4-RD RI by ≥2 points over baseline. Complete response was defined as an IgG4-RD RI <3. Partial response (PR) was defined as an IgG4-RD RI that remained ≥3. Patients who achieved an IgG4-RD RI <3 and successfully completed glucocorticoid taper were considered in disease remission (DR).