Abstract:Objective To evaluate the effectiveness of low-dose of prophylactic indomethacin in reducing the incidence of post-endoscopic retrograde cholangiopancreatography (ERCP) pancreatitis (PEP) in elderly patients. Methods From July 2021 to October 2022, patients undergoing ERCP in Zhongshan Hospital, Fudan University and Shanghai Xuhui District Central Hospital were enrolled prospectively and assigned to either the low-dose (50 mg) indomethacin group or the conventional-dose (100 mg) group using the DAS electronic central randomization system. Data from elderly patients aged≥60 were collected and compared for the incidence of PEP and other adverse reactions. Results A total of 418 elderly patients (Zhongshan Hospital, Fudan University, n=122; Shanghai Xuhui Distric Central Hospital, n=296) were ultimately included in the study, with 201 in the low-dose group and 217 in the conventional-dose group. There was no significant difference in the incidence of PEP between the low-dose group and the conventional-dose group [5.97% (12/201) VS 7.37% (16/217), χ²=0.33, P=0.566]. There was also no significant difference in drug-related adverse events between the two groups [4.98% (10/201) VS 4.15% (9/217), χ²=0.16, P=0.685]. Further subgroup analysis revealed that among elderly patients aged 60-<70, there were 13 patients diagnosed as having PEP. The incidence of PEP between the low-dose group and the conventional-dose group was not statistically significant [6.19% (6/97) VS 6.60% (7/106), χ²=0.01, P=0.903], and the occurrence of drug-related adverse events between the two groups was not statistically significant [6.19% (6/97) VS 2.83% (3/106), P=0.315]. Among elderly patients aged≥70, there were 15 patients diagnosed as having PEP. The incidence of PEP between the low-dose group and the conventional-dose group was not statistically significant [5.77% (6/104) VS 8.11% (9/111), χ²=0.45, P=0.501], and the occurrence of drug-related adverse events between the two groups was not statistically significant [3.85% (4/104) VS 5.41% (6/111), P=0.749]. Conclusion The prophylactic use of 50 mg indomethacin showed similar efficacy in reducing the incidence of PEP in elderly patients compared with 100 mg indomethacin. Therefore, elderly patients can use 50 mg indomethacin prophylactically to reduce the incidence of PEP.