Investigation of Predictive Factors for Disease Progression or Relapse of Autoimmune Pancreatitis

Abstract

Background: Some patients with autoimmune pancreatitis (AIP) suffer from disease progression during follow-up with no medication or from relapse after steroid treatment. Aim: To elucidate the proportion of patients with AIP showing disease progression or relapse and its predictive factors. Patients: Thirty-eight patients with AIP based on HISORt criteria from 1988 to 2010 were included in this study. Results: Of the 38 patients, 10 with histologically confirmed AIP after resection were followed-up conservatively with no medication. One patient (10%) developed relapse of AIP in the remnant pancreas. Of the other 28 patients, 14 were followed up without surgery or medication (median follow-up period: 1525 days), 2 of which (14.3%) showed disease progression and received steroid treatment. The remaining 14 patients received steroid treatment (initial dose: 30-60 mg/day) because of symptoms, and all of them achieved remission. In 7 of these 14 patients, steroid treatment was stopped (period to discontinuance of the treatment: 23-1366 days), and 4 of these 7 (57.1%) developed relapse (period to relapse: 19-737 days). The remaining 7 patients received maintenance treatment with low-dose steroid (period of maintenance treatment: 155-2749 days), 1 of which (14.3%) developed relapse after 265 days from initial steroid administration. Sex, age, diabetes mellitus (DM), icterus, serum IgG4 level, diffuse pancreatic swelling, other organ involvement (OOI), steroid treatment, and maintenance treatment with low-dose steroid were investigated with univariate analysis in 30 patients of AIP who had been followed up for more than 6 months to evaluate the predictive factors for disease progression or relapse, the results being as follows: male (p=0.623, OR: 1.1, 95%CI: 0.2-7.5), age less than 70 y.o. at onset (p=0.004), icterus (p=0.288, OR: 3.3, 95%CI: 0.3-32.3), DM (p=0.659, OR: 1.0, 95%CI: 0.2-5.0), serum IgG4 level >500 mg/dl (p=0.651, OR: 1.1, 95%CI: 0.28.1), diffuse pancreatic swelling (p=0.223, OR: 2.9, 95%CI: 0.5-16.4), OOI (p=0.541, OR: 1.4, 95%CI: 0.2-9.2), steroid treatment (p=0.195, OR: 2.9, 95%CI: 0.6-15.6) and maintenance treatment with low-dose steroid (p=0.480, OR: 2.1, 95%CI: 0.2-20.8). Multivariate analysis including age, diffuse pancreatic swelling and steroid treatment, which showed p<0.25 by univariate analysis, revealed that only age less than 70 y.o. at onset was a significant factor of disease progression or relapse (p=0.049). Conclusion: Disease progression or relapse was observed in 10% of resected cases, 14% of cases without medication, 57% of cases with discontinuance of steroid therapy after remission, and 14% of cases with low-dose steroid therapy. Age at onset ( less than 70 y.o. ) was considered as the predictive factor of disease progression or relapse of AIP.