Extracorporeal shock wave lithotripsy for pancreatic duct stones: an observational study.

Introduction: Previous studies suggest that fragmentation of pancreatic duct stones (PDS) using extracorporeal shock wave lithotripsy (ESWL) is associated with pain relief. However, the treatment may not be effective in certain subgroups. Aim: To evaluate predictors of pain relief after ESWL in patients with chronic pancreatitis and PDS. Methods: Retrospective study including patients with chronic pancreatitis undergoing ESWL for painful PDS. Analgesic use before and after the ESWL procedure was registered. We defined adequate pain relief after ESWL as 'pain-free without analgesics or with use of weak analgesics as needed'. The study was approved by the Danish Data Protection Agency (approval number: AHH-2017-048). Results: We included 81 patients (median age 58 years; 63% men; 68% alcoholic pancreatitis). Patients underwent one to seven ESWL procedures (mean 1.7). A concurrent ERCP was performed in 17%. All patients used analgesics before the ESWL procedure (68 used opioids). After ESWL, 43 still used opioids. Thirty-two patients achieved adequate pain relief. Univariable regression analysis showed that older age predicted adequate pain relief (OR 1.09;1.03-1.16; p = .002) as did location of the stone in the head or neck (OR 2.59;1.04-6.45; p = .041). In multivariable analysis, we found that the only two predictors of adequate pain relief were age (p = .002) and the location of the stones (p = .039). Conclusion: After the ESWL, about four out of ten patients are pain-free without medication or able to manage their pain with weak analgesics. Age and the location of the stones may be considered when evaluating if patients are eligible for referral to ESWL.