Monitoring and predicting disease activity in autoimmune pancreatitis with the M-ANNHEIM-AiP-Activity-Score.

ABSTRACT

BACKGROUND & OBJECTIVES: Autoimmune pancreatitis (AiP) is treated by immunosuppressive therapy. Exact description of disease activity of AiP is essential in clinical practice and research, but a score to describe the disease activity is missing. Thus, we aimed to establish an activity score of AiP. METHODS: We retrospectively studied long-term disease courses of 29 patients with AiP (Mannheim, Germany), receiving corticosteroid treatment (CST) by analyzing 613 treatment appointments. Two assumptions were made First, disease activity is higher at emergency treatments; second, disease activity drops under CST. In all patients, we evaluated established activity- and classification-systems of chronic pancreatitis (cP). Based on the most suitable system, we established an activity score of AiP by including AiP-specific parameters identified from our long-term disease courses and the literature. The new AiP-specific activity score was validated in an external cohort of 14 patients with AiP (Stockholm, Sweden). RESULTS: Within published activity indexes of cP, the M-ANNHEIM-classification most significantly correlated with emergency- and treatment-dependent disease activities (p < 0.001 and p < 0.01, conditional-logistic-regression-analysis). Significant correlations of disease activity were found for several clinical parameters (biliary involvement, extrapancreatic lesions, acute pancreatitis, focal pancreatic mass, pancreatic sausage/mass, focal enlargement, ascites; p < 0.05, Wilcoxon-signed-rank-test). Based on these data and disease features from the literature, the M-ANNHEIM-AiP-Activity-Score (MAAS) was established. CST-induced reduction of MAAS disease activity of more than 60% was associated with lower relapse rates (p < 0.05; Chi-Square-test). The results were validated in the external patient cohort. CONCLUSION: The MAAS might represent a useful tool to monitor AiP.