Incidence and risk factors for post-ERCP pancreatitis in chronic pancreatitis

Background and Aims: Almost all studies on post-ERCP pancreatitis (PEP) have mainly involved patients with biliary diseases rather than chronic pancreatitis (CP), and the concept that CP seems to be a protective factor associated with PEP has not been studied in detail. The aim of this study was to determine the incidence of PEP in patients with CP at different clinical stages and to identify the predictive and protective factors of PEP in a large cohort. Methods: In this observational cohort study, medical records of patients with CP (CP group) and biliary diseases (BD group) in a tertiary hospital from January 2011 to May 2015 were examined. The difference in the incidence of PEP between CP group and BD group and the risk of PEP at different clinical stages of CP were calculated by the chi(2) test or the Fisher exact test. The predictive and protective factors for PEP were investigated by univariate and multivariate analysis. Results: In total, 2028 ERCP procedures were performed in 1301 patients with CP and 2000 procedures in 1655 patients with BD. The overall incidence of PEP in CP group (4.5%) was similar to that in the BD group (4.8%; P = .747). However, CP patients had significantly lower rates of moderate and severe attacks (0% vs 1.3%, P < .01). According to the M-ANNHEIM classification, the PEP incidences of CP at stages 0, I, II, III, and IV were 4.4%, 5.1%, 3.8%, 2.0%, and 2.0%, respectively. CP patients at stage Ia had the highest PEP incidence (8.0%) among all CP patients, significantly higher than that at stages Ib + Ic (3.9%) and II (3.8%). Female gender, history of acute pancreatitis, and prior PEP were independent risk factors of PEP, whereas extracorporeal shock wave lithotripsy was a protective factor. Conclusions: Compared with BD patients, CP patients had similar incidence of PEP overall but lower grades of severity. The incidence of PEP in CP patients decreased significantly with disease progression.