Review for 10.1186/s12876-023-02668-9 (2023)

Title: Comparison of therapeutic efficacy and treatment costs of Self-Expandable Metal Stents
and Plastic Stents for Management of Malignant Biliary Obstruction
Version: 2 Date: 26 Dec 2022
Reviewer's report:
Manuscript summary
This paper looks at the cost-effectiveness and efficacy of SEMS vs PS in the management of
unresectable distal biliary obstruction by primary pancreaticobiliary malignancy. They show
that stent patency is longer in those undergoing SEMS insertion with higher costs associated
with PS in those surviving more than 2 months.
They have clear aims with stringent exclusion criteria and clear study endpoints. The statistical
analysis is sound.
Major issues
• Study period is not defined
• In the sSEMS subgroup, only the post sSEMS costs were evaluated. Therefore, this is not a
true representation of the costs associated with the patient journey that begins with a PS.
• It is not clear if the sSEMS cohort included the same patients in the PS or if this was an entirely
different group of patients
• Very high complication rates, which needs to be explained in further detail with a definition
of what constitutes a complication in this analysis
o It would be worthwhile to include those associated with stent insertion (e.g. Post ERCP
pancreatitis, bleeding etc.) vs those associated with the duration of stenting, such as tumour
ingrowth
Minor issues
Abstract
• Background
o Adjust the first sentence to `According to the European Society of Gastrointestinal Endoscopy
guidelines...`
o The second sentence should start with The aim
o There is no consistency in the use of SEMS and PS vs SEMSs and PSs
• Methods- Remove Of and change 135 to one hundred and thirty-five
• Results
o Adjust this sentence to ` functional success rate (90.10% vs 86.27%). SEMSs...`
• Conclusion
o Last sentence should read `If SEMS is not...`
Main document
• Background
o Restructure this sentence `These tumors are among the most lethal neoplasms; the prognosis
is dismal, and the rate of mortality and incidence are 94%.[1]` . It is not clear what incidence
refers to and the language is sensationalist
o Stick to PS and SEMS
o This sentence needs to be substantiated with a reference `Although several international
gastroenterological societies recommend the placement of SEMSs with ERCP for the
management of malignant biliary obstruction, the use of PSs has not yet substantially decreased.`
• Results
o Remove However from this sentence ` However, mean survival was substantially longer`
o This sentence is not clear and I am unsure what the authors are referring to. It needs to be
restructured for clarity `All neoplasms located on the CBD without the involvement of hilar part,
and most frequently suprapapillary biliary obstruction was detectable (77.04%).`
o PS recipients surviving longer than 3-4 months would have had scheduled stent replacements.
Why these stents were not replaced should be included after this sentence `this trend was also
observed among patients who survived more than 4 months (PS: 2.20 ± 1.15; pSEMS: 1.26 ±
0.56; sSEMS: 1.84 ± 1.51; p < 0.0812).`
• Limitations
o There is an undefined study period and therefore, changes in oncological management of the
patients may influence survival periods