Title: A combined prediction model for biliary tract cancer using the prognostic nutritional index
and pathological findings: a single-center retrospective study
Version: 2 Date: 19 Jun 2021
Reviewer's report:
Authors explored the prognostic factors using a cohort of 117 patients with biliary tract cancer
who underwent surgical resection in their institution. They reported that prognostic nutritional
index, lymph node metastasis, and tumor differentiation remained independent prognostic
factors after multivariate analysis. In addition, they developed a combined prediction model
using these 3 independent prognostic factors.
This reviewer has several major concerns as follows.
1. The reproducibility of prediction models should be validated in an independent cohort. If
no independent cohort  is available, other methods such as bootstrapping could be applied to
validate its performance.
2. Is prognostic nutritional index superior to other established index such as NLR or GPS in
predicting prognosis in your cohort?
3. This was a retrospective study, but authors mentioned that  informed consent was obtained
from all individual participants.  It is unclear how authors obtained the informed consent from
the deceased patients.
Title: A combined prediction model for biliary tract cancer using the prognostic nutritional index
and pathological findings: a single-center retrospective study
Version: 2 Date: 19 Jun 2021
Reviewer's report:
Authors explored the prognostic factors using a cohort of 117 patients with biliary tract cancer
who underwent surgical resection in their institution. They reported that prognostic nutritional
index, lymph node metastasis, and tumor differentiation remained independent prognostic
factors after multivariate analysis. In addition, they developed a combined prediction model
using these 3 independent prognostic factors.
This reviewer has several major concerns as follows.
1. The reproducibility of prediction models should be validated in an independent cohort. If
no independent cohort  is available, other methods such as bootstrapping could be applied to
validate its performance.
2. Is prognostic nutritional index superior to other established index such as NLR or GPS in
predicting prognosis in your cohort?
3. This was a retrospective study, but authors mentioned that  informed consent was obtained
from all individual participants.  It is unclear how authors obtained the informed consent from
the deceased patients.
Please review this paper.
user
Title: A combined prediction model for biliary tract cancer using the prognostic nutritional index
and pathological findings: a single-center retrospective study
Version: 2 Date: 19 Jun 2021
Reviewer's report:
Authors explored the prognostic factors using a cohort of 117 patients with biliary tract cancer
who underwent surgical resection in their institution. They reported that prognostic nutritional
index, lymph node metastasis, and tumor differentiation remained independent prognostic
factors after multivariate analysis. In addition, they developed a combined prediction model
using these 3 independent prognostic factors.
This reviewer has several major concerns as follows.
1. The reproducibility of prediction models should be validated in an independent cohort. If
no independent cohort  is available, other methods such as bootstrapping could be applied to
validate its performance.
2. Is prognostic nutritional index superior to other established index such as NLR or GPS in
predicting prognosis in your cohort?
3. This was a retrospective study, but authors mentioned that  informed consent was obtained
from all individual participants.  It is unclear how authors obtained the informed consent from
the deceased patients.
assistant