Review for 10.1186/s12876-022-02126-y (2022)

Reviewer’s report
Title: 
Association between plasma level of superoxide dismutase and survival of
patients with acute-on-chronic liver failure
Version: 
1 
Date: 
23 Nov 2021
Reviewer's report:
The association between oxidative stress and survival analysis in patients with
Acute-On-Chronic Liver disease is an interesting topic. I read with interest this
manuscript by Zhen Tian et al. 
The manuscript is well written. The results section and discussion section are too
long. 
The authors showed that the Plasma Superoxyde Dismutase level, measured at
hospital admission can be used to identify patients with ACLF at high risk of
death. In addition, the combination SOD level and MELD score predicts the
outcome. 
The authors, with their results, must convince the authors of the interest of such
a dosage in the management of the patients with ACLF. For example, the
superiority of this combination SOD level and MELD score compared to the
number of organ failures for a registration on the waiting list of LT. 
There are some defects (in particularly in the methodology and in the results
section) in this manuscript as follows: 
1) The authors use the APASL criteria for ACLF diagnosis. This choice limits
the impact of the results on the european and american readers. I invite the
authors to use European / American definitions (Moreau Gastroenterology
2013). In addition, no patient information are available : cause of cirrhosis,
hospitalization reason, clif sofa score, Meld score for cirrhosis patients, previous
complications (bleeding, infection, ascites…), organ failure ? in which unit are
patients hospitalized ? 
2) Blood sample were collected at admission and 14 days after hospital
admission. Why chose 14 days ? Please explain. how many patients did not get
the second sample ? Does the second dosage change the results of the research?
3) The authors performed a cohort study of adult LT including 124 patients with
ACLF, 30 cirrhotic patients and 30 Healthly controls (Table 1). In the method
section and Line 50-55 the authors compare ACLF patients and ALF patients.
Who are these patients ? There is no information about these patients in the table
1. 
Minor Concerns: 
The introduction section is clear. Please delete the sentence or modify the
sentence: lines 40-46 (introduction section). I agree that there are some scoring
systems for assessing the ACLF severity and the prognostic of patients with
ACLF. However, the best system is the CLIF-SOFA score. 
Please delete the standard formula of MELD score. Today, the reader knows it. 
The results section and discussion section are too long. 
Line 54-56 (results section): it is a commentary. Please delete these sentences
from the results section. In addition the sentence "about MELD score > 25 in
patients with ALF" and "association of plasma SOD levels …" are not results but
more comments. Put it in the discussion paragraph.
Some abbreviations have been used in the text and in the Tables. However, the
abbreviations used although explained in the manuscript are not the international
abbreviations. can you correct this?
(Ex fibrinogen : Fb instead of FIB, Prothrombin time: PT instead of PTA)….
There are some typographical errors. Please check and change them. 
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Is the study design appropriate to answer the research question (including the use
of appropriate controls), and are the conclusions supported by the evidence
presented?
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Are the methods sufficiently described to allow the study to be repeated?
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Yes
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from apparent manipulation?
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