Real-world impact of implementing lumen-apposing metal stents for pancreatic fluid collections: a nationwide Japanese study

Background Lumen-apposing metal stents (LAMSs) are increasingly used for the endoscopic management of pancreatic fluid collections (PFCs), including walled-off necrosis (WON) and pancreatic pseudocysts (PCs). Objective To evaluate the nationwide impact of implementing an LAMS (approved in Japan in 2018) on clinical outcomes in real-world settings. Design Using a nationwide inpatient database, we identified 5885 patients who underwent endoscopic ultrasound (EUS)-guided treatment for PFCs at 550 hospitals between 2010 and 2023. We examined the association between treatment period (pre-LAMS vs post-LAMS implementation) and clinical outcomes. Multivariable logistic and linear regression analyses were performed to estimate ORs and coefficients, respectively. Findings were validated using a multi-institutional clinical cohort (n=618) from specialty hospitals with more detailed clinical parameters with data collection during the same period. Results In the pre-LAMS period, 3787 cases were treated exclusively with plastic stents. After 2018, LAMS use stabilised at around 50% among 2098 cases treated between 2019 and 2023. Compared with the pre-LAMS period, patients treated during the post-LAMS period had a higher risk of bleeding with LAMS (adjusted OR, 1.81; 95% CI: 1.55 to 2.13), but not with plastic stents (adjusted OR, 0.96; 95% CI: 0.74 to 1.26). Rates of rescue surgery, in-hospital mortality and length of stay did not differ significantly (p>0.12). The post-LAMS period was associated with increased total costs (adjusted coefficient, US$2813; 95% CI: 1503 to 4122). In analyses stratified by PFC types (WON vs PC), the association of the post-LAMS period with bleeding risk appeared to be stronger for PCs than WON (p interaction =0.015) and WON patients had a shorter length of stay and lower total costs in the post-LAMS period (p interaction <0.001). In the validation cohort, the elevated bleeding risk with LAMS was confirmed (adjusted OR, 1.59; 95% CI: 0.86 to 2.95, vs pre-LAMS period), though not statistically significant. Conclusions The implementation of LAMS was not associated with improved key clinical outcomes but was linked to a higher risk of bleeding and increased healthcare costs. These findings do not support the routine use of LAMS for EUS-guided treatment of all PFCs in standard clinical practice but may restrict it to WON cases with clear indications.