Predicting the need for step-up after EUS-guided drainage of peripancreatic fluid collections, including Quadrant Necrosis Infection score validation: a prospective cohort study.

Background And Aims: Factors predicting the need for step-up procedures after EUS-guided drainage (EUS-FCD) of peripancreatic fluid collections (PFCs) were explored in retrospective studies restricted to Walled-Off Necrosis (WON) and Lumen Apposing Metal Stents (LAMS).

Methods: All consecutive candidates for EUS-FCD between 2020-2024 were included in a Prospective Registry of Therapeutic EUS (PROTECT, NCT04813055), with prospective monthly follow-up evaluating clinical success, adverse events and recurrences. Prospectively assessed baseline clinical and morphological factors, including the Quadrant-Necrosis-Infection (QNI) classification, were included in a stepwise logistic regression model to predict the need for step-up. The agreement between EUS and Radiology in assessing the extent of necrosis was compared with Cohen's kappa.

Results: Seventy patients (29 post-surgical collections, 21 pseudocysts, and 20 WONs) were treated with double-pigtail plastic stents (DPPS) in 59% of cases and LAMS in 41%. Clinical success was 92.9%, with a need for step-up (mostly endoscopic necrosectomy) in 35.7% of cases. Necrosis ≥60% (OR=7.7, 95%CI 1.4-43) and being in the high-risk QNI group (OR=4.6, 95%CI 1.4-15) were the only independent predictors of any step-up. The same factors predicted the endoscopist's decision to allocate PFCs to LAMS vs. DPPS. The high-risk QNI group was associated with a significantly longer hospital stay (12 days vs. 4 days, p=0.004). EUS tended to upscale the necrotic content compared to preprocedural Radiology (κ=0.31) CONCLUSIONS: The extent of necrosis and the QNI classification strongly correlated with the need for step-up and allocation to LAMS vs. DPPS drainage, proposing a central role in treatment personalization.