Review for 10.1186/s12876-021-01614-x (2021)

Reviewer’s report
Title: 
Evaluation of Role of Hyperbilirubinemia as a New Diagnostic Marker of
Complicated Appendicitis.
Version: 
3 
Date: 
19 Nov 2020
Reviewer's report:
Thank you for the revision. The manuscript has been improved substantially.
Still, I think some of the tables should be refined, and it would be better to have
less tables and figures in the manuscript.
e.g. 
- There were multiple or a combination of figures and tables under the same
name (for example, Figure 12 actually had 2 figures and 1 table).
- The table at the bottom of Table 2 can be dismissed, because all of the
information were explained in the text of the manuscript.
- The threshold table for the ROC curve (table 3) is not really necessary, and
might be omitted; the ROC should be sorted under "Figure", not "Table".
Under the COMPARISON OF PRE-OPERATIVE AND POST-OPERATIVE
DAY 7 TOTAL BILIRUBIN LEVEL section
- I think it would be better to separately compare the the changes between pre-
and post-operative total bilirubin in the complicated and uncomplicated group,
rather than in all patients.
I believe it would give a clearer picture about the role of total hyperbilirubinemia
in complicated appendicitis (total bilirubinemia in the the complicated group
reduced significantly, while the level remained the same in the uncomplicated
group).
- Please change the data in the Table 2 accordingly.
For the multivariable analysis
- There were too many variable included, and that might make the model
unstable. Please considered adding only the variables that were significant in
univariate analysis (for example, ALT, AST, ALP were not significant, and
shouldn't be included in the model). Likewise, please also consider adding the
variable that seems strongly significant in the univariate analysis to the model
(e.g. fecolith and periappendiceal collection).
- Some continuous variable that did not have an exact cut-off point (for example:
appendix diameter in USG (mm), duration of pain (hrs)), should be included as
is. The logistic regression can accept and analyze continuous variable. Don't
make up a cut-off point unless a proper statistical analysis of those cut-off had
been done
for example:
(i) the 9 hrs cut-off for the duration of pain --> 9 hours is the means of the
duration in the uncomplicated group; that means approximately half of patients
with uncomplicated appendicitis would have pain more than 9 hours. So this is
not an appropriate cut-off value.
(ii) the 8 mm cut-off for the appendiceal diameter --> the cut-off diameter used
in the univariate analysis was 7.6 mm, why choosing 8 mm in the multivariate
analysis? 
Thank you
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