IDDF2022-ABS-0127 Plastic versus metal stent for endoscopic ultrasound-guided transmural drainage of walled-off necrosis with significant solid debris: a randomised controlled noninferiority trial

Background Recently large-calibre metal stents are increasingly being used, assuming higher efficacy compared to plastic stents. However, the better efficacy of metal stents is not proven by existing studies. Treatment success was not the primary outcome of the previous RCT, which is the major endpoint. Hence, we conducted non-inferiority RCT (Plastic stents are not inferior to metal stents). Methods This single-centre, open-label, RCT enrolled 48 patients with symptomatic WON (>20% solid debris). The primary outcome was treatment success (symptom plus radiological resolution) of WON. Secondary outcomes were technical success rate, number of procedures required, adverse event, procedure duration, and treatment failure. We assessed all outcomes three weeks after drainage with cross-sectional imaging. Patients were followed up for three months to determine recurrence. Results 24 patients were randomised in each arm. The treatment success was achieved in 21(p1=87.5%) and 20(p2=83.3%) patients in metal stent and plastic stent groups, respectively, with P1/p2 being 1.05 [95% confidence interval (CI) is 0.81 to 1.39]. Assuming a 10% noninferiority margin using the Gart Nam score method, the p-value was <0.001 for non-inferiority. As the noninferiority p-value was below the threshold, we conclude that the plastic stent is non-inferior to the metal stent. However, lower CI indicates a lack of power for a definite conclusion. The secondary outcomes were comparable in both groups (IDDF2022-ABS-0127 Table 1). DPDS was present in 41/48 (87.5%) patients. One asymptomatic recurrence was seen in the metal stent. Conclusions Plastic stents are not inferior to the metal stent in terms of treatment success in transmural drainage of WON. However, a large study is needed to make definite conclusions.