Introduction: Endoscopic retrograde cholangiopancreatography (ERCP) training guidelines are evolving to be more competency-based in the absence of a standardized curriculum. We aimed to determine the effect of trainee involvement and center volume influences the ERCP scope time (ST), total procedural time (TPT), and fluoroscopy time (FT). Methods: Patients from Clinical Outcome Research Initiative National Endoscopic Database CORI-NED (2009-2014) who underwent ERCP were stratified based on the trainee participation (trainee participated vs. not participated), center volume (ERCPs performed >200/year-high volume (HV), 100-200/ year- intermediate volume (IV), < 100 per year-low volume (LV)). ST was defined as the time interval between ERCP scope insertion and withdrawal, TPT as the time interval requiring ERCP intervention, and FT as the time interval fluoroscopy activated. The time variables were compared against trainee involvement and ERCP center volume using the Kruskal-Wallis test and significance level defined for a p-value < 0.05 (Table 1). Results: A total of 13,855 ERCPs, comprising trainee participation (n= 6488) and non-participation (n=7367) were performed at HV (n=2220), IV (n=5062) and LV (n=6573) centers respectively. Trainee participation vs. non-participation significantly increased ST [31(20-40) versus 23.5(16-38.5), p< 0.014, Fig 1a], TPT [28 (24-48) vs. 24 (17.75-41.25), p< 0.00, Fig 1b]. However, FT was unaffected by trainee participation or non-participation (Fig 1c). HV vs. LV ERCP centers were significantly associated with prolonged ST [36(22.5-58) versus 24(16-39), p< 0.001)], TPT [36(25.5-61) vs. 28(18-42), p< 0.001)] and FT [6(3.5-9) vs. 2(1-2), p< 0.001)], respectively. HV vs. IV ERCP centers were significantly associated with prolonged ST [36(22.5-58) versus 31(16.5-46), p< 0.001)]. HV vs. IV centers were not associated with prolonged TPT [36(25.5-61) vs. 35(28-58.5), p=NS)] and FT was only marginally prolonged to statistical significance [6(3.5-9) vs. 5(2.5-11), p=0.03)], (Fig 1 d,e,f). Conclusion: Trainee involvement in ERCP interventions is associated with significantly longer scope time, total procedural time, and fluoroscopy time. Differences were similar for scope time and fluoroscopy time comparing HV centers with IV centers, but no difference was noted for total procedure time. It is anticipated that these findings will have a profound impact on structuring ERCP training and resource utilization.Table 1.: Pair-wise comparisons of scope time, total procedure time, and fluoroscopy time (minutes) across independent variables (trainee participation and center volume). DF#- degrees of freedom, IQR*-interquartile range, H (c2 chi-square statistic) for Kruskal Wallis test, NS-not significant.Figure 1.: Comparison of the various intraprocedural time intervals during ERCP with trainee participation and procedure volume.