Benefits of Therapeutic Endoscopic Retrograde Cholangiopancreatography in Patients Admitted with Acute Gallstone Pancreatitis: A Nationwide Cohort Study

Thesis (Master's)--University of Washington, 2017-06Introduction: Acute gallstone pancreatitis is the most common gastrointestinal cause for hospital admission. Endoscopic retrograde cholangiopancreatography (ERCP) with sphincterotomy and/or stone extraction from the common bile duct could be beneficial in preventing recurrence. However, previous trials showed mixed results, with no effect on in-hospital outcomes such as mortality, complications, severity, and length of stay. Aim: To examine the association between ERCP during an admission for acute gallstone pancreatitis and subsequent emergent encounters and readmissions for recurrent pancreatitis and other causes. Methods: We performed a retrospective cohort study using the Truven Health Marketscan Databases, which capture person-specific clinical utilization, expenditures, and enrollment across inpatient, outpatient, prescription drug, and carve-out services for subjects with employer based health insurance. All admissions from the inpatient admissions table with a primary diagnosis of acute pancreatitis were extracted using the ICD-9-CM code for acute pancreatitis, with gallstone pancreatitis identified by using additional codes for cholelithiasis. Details regarding inpatient admissions, inpatient services used, outpatient services used, and demographic variables were collected. The exposure was having undergone a therapeutic ERCP during the admission, defined as an ERCP with sphincterotomy and/or stone extraction. The primary outcome of interest was persistent / recurrent pancreatitis following discharge from the index admission. Secondary outcomes included all-cause emergent encounters, all-cause emergent readmissions, and all-cause emergent readmission within 30 days of discharge. Survival analysis methods with Cox proportional hazards models were used to examine the primary and secondary outcomes and to adjust for potential covariates. Logistic regression was used for the secondary outcome of all-cause emergent readmission within 30 days of discharge. To further examine the relationship between ERCP and recurrent pancreatitis in patients with acute gallstone pancreatitis, propensity scores for receiving ERCP were generated, and Cox proportional hazards model, stratified by cholecystectomy status, was subsequently fit with inverse probability weighting based on propensity scores. Results: There were 17,348 patients in our study who met inclusion criteria, of whom 3,375 patients (19.5%) underwent a therapeutic ERCP. Compared to those who did not undergo therapeutic ERCP, patients who received therapeutic ERCP during the index admission tended to be female, have fewer comorbidities, and have a longer length of stay. Adjusting for patient characteristics, comorbidities, severity of acute pancreatitis, clinical factors, and cholecystectomy status, patients undergoing therapeutic ERCP had a lower hazard of recurrent pancreatitis following discharge from the index admission (HR 0.71, 95% CI 0.59-0.84, p < 0.001). This was especially true for patients who were discharged with gallbladder in situ (0.64, 95% CI 0.50 – 0.82, p < 0.001), but not for those who underwent cholecystectomy prior to discharge. The results of the analysis using adjustment for confounders via inverse probability weighting based on propensity for therapeutic ERCP further indicate that the hazard for recurrent pancreatitis is reduced for patients as long as the gallbladder remains in situ (HR 0.45, 95% CI 0.30 – 0.68, p < 0.001), but not once the gallbladder is removed (HR 0.96, 95% CI 0.66 – 1.39). Moreover, therapeutic ERCP was associated with lower hazard of all-cause emergent encounters (HR 0.86, 95% CI 0.80-0.92, p < 0.001) and all-cause readmissions following discharge (HR 0.81, 95% CI 0.71-0.91, p= 0.001). Conclusion: Therapeutic ERCP is associated with reduction in recurrent pancreatitis, all-cause emergent encounters, and all-cause readmissions following discharge in patients initially admitted for acute gallstone pancreatitis. This procedure should especially be considered in patients who are being discharged with gallbladder in situ