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: 27 Sep 2022
Reviewer's report:
Thank you for this study on the cost-effectiveness of SEMS versus plastic stents for malignant
biliary obstruction. Unfortunately, I recommend rejection of this submission.
Ultimately, this study attempts to analyze effectiveness of PS vs SEMS but does not account
for indication of use in the efficacy analysis which make the results difficult to interpret
meaningfully, and separately analyzes cost where the three groups are better defined but cost per
month is an unclear outcome. This study does not assess cost-effectiveness – this is a different
concept than examined in this study. If there are patients who received plastic versus metal stents
for each of the 3 indications assessed, this efficacy and cost data could be used as parameter
estimates to create decision tree using a Markov model for a cost-effectiveness analysis.
Please cite data supporting the assertion that the use of plastic stents has not substantially
decreased despite recommendation for SEMS.
Stating that you are conducting a cost-effectiveness analysis implies that a decision tree analysis
to assess an outcome such as life-year gained or death prevented. Here, you simply examine
costs in a single center in a single country. Please explain further how this analysis
You state this was a retrospective study. Did all patients receive treatment following guidelines
only? Were patients who may not have received guidelines-directed therapy for whatever clinical
reason excluded? How can this be controlled for in retrospective inclusion criteria, or was there
a prospective enrollment with these criteria?
What were the dates of the study period?
The use of the word subgroup is confusing – there are 3 groups being compared, but no further
subgroups.
If the indications for plastic (potentially resectable) versus metal stents (potentially unresectable)
are different, how can their cost-effectiveness be compared?
Selectively only including the post-SEMS cost in the sSEMS group is misleading; why is the
initial SEMS cost not relevant?
Please comment on why survival rates
Why does the efficacy analysis not compare the 3 different groups as indicated in the methods for
primary outcomes? How do you account for multiple procedures required by individual patients?
Here, this analysis is flawed due to confounding by indication for type of stent placement.
Does literature support the use of average cost of treatment per month of survival as a way to
control for variable survival time? This seems to yet be another manifestation of confounding
by indication and it is unclear if this is an appropriate way to control for it.
Please comment on the generalizability of cost data to an international audience.
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: 27 Sep 2022
Reviewer's report:
Thank you for this study on the cost-effectiveness of SEMS versus plastic stents for malignant
biliary obstruction. Unfortunately, I recommend rejection of this submission.
Ultimately, this study attempts to analyze effectiveness of PS vs SEMS but does not account
for indication of use in the efficacy analysis which make the results difficult to interpret
meaningfully, and separately analyzes cost where the three groups are better defined but cost per
month is an unclear outcome. This study does not assess cost-effectiveness – this is a different
concept than examined in this study. If there are patients who received plastic versus metal stents
for each of the 3 indications assessed, this efficacy and cost data could be used as parameter
estimates to create decision tree using a Markov model for a cost-effectiveness analysis.
Please cite data supporting the assertion that the use of plastic stents has not substantially
decreased despite recommendation for SEMS.
Stating that you are conducting a cost-effectiveness analysis implies that a decision tree analysis
to assess an outcome such as life-year gained or death prevented. Here, you simply examine
costs in a single center in a single country. Please explain further how this analysis
You state this was a retrospective study. Did all patients receive treatment following guidelines
only? Were patients who may not have received guidelines-directed therapy for whatever clinical
reason excluded? How can this be controlled for in retrospective inclusion criteria, or was there
a prospective enrollment with these criteria?
What were the dates of the study period?
The use of the word subgroup is confusing – there are 3 groups being compared, but no further
subgroups.
If the indications for plastic (potentially resectable) versus metal stents (potentially unresectable)
are different, how can their cost-effectiveness be compared?
Selectively only including the post-SEMS cost in the sSEMS group is misleading; why is the
initial SEMS cost not relevant?
Please comment on why survival rates
Why does the efficacy analysis not compare the 3 different groups as indicated in the methods for
primary outcomes? How do you account for multiple procedures required by individual patients?
Here, this analysis is flawed due to confounding by indication for type of stent placement.
Does literature support the use of average cost of treatment per month of survival as a way to
control for variable survival time? This seems to yet be another manifestation of confounding
by indication and it is unclear if this is an appropriate way to control for it.
Please comment on the generalizability of cost data to an international audience.
Please review this paper.
user
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: 27 Sep 2022
Reviewer's report:
Thank you for this study on the cost-effectiveness of SEMS versus plastic stents for malignant
biliary obstruction. Unfortunately, I recommend rejection of this submission.
Ultimately, this study attempts to analyze effectiveness of PS vs SEMS but does not account
for indication of use in the efficacy analysis which make the results difficult to interpret
meaningfully, and separately analyzes cost where the three groups are better defined but cost per
month is an unclear outcome. This study does not assess cost-effectiveness – this is a different
concept than examined in this study. If there are patients who received plastic versus metal stents
for each of the 3 indications assessed, this efficacy and cost data could be used as parameter
estimates to create decision tree using a Markov model for a cost-effectiveness analysis.
Please cite data supporting the assertion that the use of plastic stents has not substantially
decreased despite recommendation for SEMS.
Stating that you are conducting a cost-effectiveness analysis implies that a decision tree analysis
to assess an outcome such as life-year gained or death prevented. Here, you simply examine
costs in a single center in a single country. Please explain further how this analysis
You state this was a retrospective study. Did all patients receive treatment following guidelines
only? Were patients who may not have received guidelines-directed therapy for whatever clinical
reason excluded? How can this be controlled for in retrospective inclusion criteria, or was there
a prospective enrollment with these criteria?
What were the dates of the study period?
The use of the word subgroup is confusing – there are 3 groups being compared, but no further
subgroups.
If the indications for plastic (potentially resectable) versus metal stents (potentially unresectable)
are different, how can their cost-effectiveness be compared?
Selectively only including the post-SEMS cost in the sSEMS group is misleading; why is the
initial SEMS cost not relevant?
Please comment on why survival rates
Why does the efficacy analysis not compare the 3 different groups as indicated in the methods for
primary outcomes? How do you account for multiple procedures required by individual patients?
Here, this analysis is flawed due to confounding by indication for type of stent placement.
Does literature support the use of average cost of treatment per month of survival as a way to
control for variable survival time? This seems to yet be another manifestation of confounding
by indication and it is unclear if this is an appropriate way to control for it.
Please comment on the generalizability of cost data to an international audience.
assistant