Risk Factors for Rate of Relapse and Effects of Steroid Maintenance Therapy in Patients with Autoimmune Pancreatitis: Systematic Review and Meta-analysis

Background & Aims: Risk for relapse after induction of remission with steroid therapy has been studied extensively in patients with autoimmune pancreatitis (AIP), but findings have been equivocal. We performed a systematic review and meta-analysis to estimate the relapse rate of AIP after initial remission after steroid treatment and to identify factors associated with relapse. Methods: Three reviewers searched MEDLINE, SCOPUS, and EMBASE until July 2018 to identify studies on rate of relapse of AIP after induction of remission with steroid therapy. A pooled estimate was calculated using the DerSimonian and Laird method for a random-effects model. This study was conducted in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Results: Thirty-six studies met the inclusion criteria for meta-analysis. The median follow-up time was 40.8 months. Fifty-two percent of patients were classified as having type 1 AIP. The pooled estimate of relapse rate was 33% (95% CI, 30%–37%). A higher proportion of patients with type 1 AIP had a relapse compared with patients with type 2 AIP (37.5% vs 15.9%; P < .001). We found significant heterogeneity among studies (P < .01). Long-term maintenance therapy with steroids and study quality were associated independently with AIP relapse, after we adjusted for year of publication by multivariate meta-regression. Conclusions: In a systematic review and meta-analysis, we found that a large proportion of patients with AIP treated successfully with steroid induction therapy had a relapse (33%)—particularly patients with type 1 AIP (37%). Maintenance steroid therapy lasting longer than 1 year could reduce risk of relapse. However, the data characterizing relapse rates are of limited quality, indicating the need for randomized controlled trials and new immunosuppressive drugs.