Low-dose maintenance steroid treatment could reduce the relapse rate in patients with type 1 autoimmune pancreatitis: a long-term Japanese multicenter analysis of 510 patients.

Abstract

The effect of maintenance steroid treatment (MST) in reducing the risk of relapse in patients with autoimmune pancreatitis (AIP) remains under debate. The aim of this study was to validate the effect of MST on AIP administered in accordance with the 2010 Japanese consensus guidelines. The clinical data of patients with (n=510) from 22 high-volume centers in Japan were studied. The primary endpoints were the relapse rates (RRs) in patients administered MST versus those not administered MST. The secondary endpoints were the optimal dose and duration of MST in terms of steroid toxicity and the predictors of relapse. The RRs were 10.0% within 1year, 25.8% within 3years and 35.1% within 5years. The RR in the steroid therapy group reached a plateau at 42.7% at 7years. In terms of the optimal dosage, the overall RR in the MST 5mg/day group was 26.1%, which was significantly lower than that in the group which had discontinued steroid therapy (45.2%; p=0.023) or was receiving MST at 2.5mg/day (43.4%, p=0.001). The RRs in the group receiving MST at ≥5mg/day versus the patient group receiving MST at <5mg/day were 10.6 vs. 10.3% within 1year, 23.5 vs. 32.9% within 3years and 32.2 vs. 41.3% within 5years, respectively (log-rank, p=0.028). The best cutoff value of the total steroid dose for serious steroid toxicity was 6405mg, with a moderate accuracy of 0.717 determined using the area under the curve. Presence of diffuse pancreatic swelling [odds ratio OR)1.745; p=0.008) and MST at >5mg/day were identified as predictors of relapse (OR0.483; p=0.001). The RR could continue to increase for 7years even under MST. Based on our analysis of the side effects of steroid therapy, MST at 5mg/day for 2 (total 4625mg) to 3 (total 6425mg)years might be a rational and safe therapeutic strategy in terms of keeping the RR to <30% while avoiding potential steroid toxicity.