Preventive role of biodegradable pancreatobiliary stents

Table 3 Grading of Recommendations Assessment, Development and Evaluation assessment of evidence preventive role of biodegradable pancreatobiliary stents across four indications

Indication and principal outcome	Initial certainty	Risk of bias	Inconsistency	Indirectness	Imprecision	Publication bias	Final certainty
PEP prophylaxis: Incidence and severity of PEP	Low	Serious	Not serious	Serious	Serious	Suspected	Very low
Basis: Predominantly uncontrolled or retrospective feasibility cohorts, often with mixed indications. No adequately powered randomized comparison of biodegradable vs conventional pancreatic stents or no stent has evaluated PEP incidence
PEP prophylaxis: Avoidance of follow-up imaging and endoscopic retrieval	Low	Not serious	Not serious	Not serious	Not serious	Not detected	Moderate (rise) large effect
Basis: Avoidance of surveillance imaging and endoscopic retrieval follows almost deterministically from in-situ degradation. Across cohorts essentially no biodegradable-stent recipient required retrieval, compared with repeat endoscopy in approximately two-thirds of plastic-stent patients. Rated up one level for large magnitude of effect. This outcome reflects procedural burden, not prevention of PEP itself
Postoperative pancreatic fistula: Clinically relevant POPF after PD	High	Not serious	Not serious	Not serious	Very serious	Not detected	Low
Basis: One blinded randomized trial provides direct evidence, but only 50 of the planned 310 participants were included in the interim analysis, and few events leave substantial uncertainty around the effect on clinically relevant POPF. The interim, incomplete-accrual limitation was accounted for under imprecision rather than risk of bias to avoid double-counting; risk of bias is therefore rated not serious
PSC-related strictures: Stricture resolution and prevention of recurrent cholangitis	Low	Serious	Not assessable	Very serious	Very serious	Suspected	Very low
Basis: Direct evidence is limited to four PSC patients within a seven-patient case series involving surgically altered anatomy. Evidence of harm from conventional plastic stenting does not establish biodegradable-stent safety or effectiveness
Bile leaks: Clinical closure without recurrence or reintervention	Low	Serious	Not serious	Serious	Serious	Suspected	Very low
Basis: Direct evidence for established post-cholecystectomy bile leaks is based mainly on a small comparative cohort with eight biodegradable-stent recipients. Remaining evidence largely concerns transplant prophylaxis, post-choledochotomy use, or benign strictures

Grading of Recommendations Assessment, Development and Evaluation certainty is assigned to a specific outcome, not to a study or indication as a whole. For post-endoscopic retrograde cholangiopancreatography pancreatitis prophylaxis, two outcomes are shown: (1) Prevention of post-endoscopic retrograde cholangiopancreatography pancreatitis; and (2) Itself (very low) and avoidance of follow-up imaging and endoscopic retrieval (moderate). Animal evidence was treated as supportive and indirect and was not used to determine clinical certainty. Where certainty is already very low on the basis of risk of bias, indirectness and imprecision, suspected publication bias is documented as a concern but is not the determining factor; with fewer than approximately ten studies per outcome it could not be formally tested. Grading of Recommendations Assessment, Development and Evaluation uses four discrete categories: (1) High; (2) Moderate; (3) Low; and (4) Very low. PEP: Post-endoscopic retrograde cholangiopancreatography pancreatitis; POPF: Postoperative pancreatic fistula; PSC: Primary sclerosing cholangitis; PD: Pancreaticoduodenectomy.