Review for 10.1186/s12876-024-03302-y (2024)

Title: Prevalence, characteristics, and risk factors of non-alcoholic fatty liver disease in North
East of Iran: a population-based study
Version: 0 Date: 25 Oct 2023
Reviewer:  Habibollah Rahimi
Reviewer's report:
The manuscript has been reviewed carefully. To improve its quality there have been emerged
some items which should be treated. You can find them in below.
1- In the Study Population and Procedure section; Please determine who and how many people
conducted the sonography, in terms of discipline. If there were more than one specialist, please
explain about inter rater reliability its method.
2- In the Study Population and Procedure; please explain the method of sampling with more
details. As you know one of pitfalls in cross-sectional studies is the requirement of applying
representative samples.
3- In the materials and methods section; please explain how did you measured “body fat
percentage (BFP)”.
4- In the results section; please add non-response rate in percentage at first.
5- In the results section; the term “some frequent participants” sounds ambiguous, please use
more appropriate term.
6- In the results section_ please first report crude and standardized prevalence proportion with
confidence interval.
7- In the results section_ table 1; please calculate the percentage according to the sum of every
row, you have calculated based on the sum of column.
8- In the results section_ please organize presenting results in individual paragraphs, in other
words in every paragraph just present a group of findings (a paragraph for demographic
variables, a paragraph for metabolic findings and so on).
9-  In the results section_ the authors have inserted individual significant P-value for each
variable (triglyceride (P=0.047), AST (P=0.019), and ALT (P=0.001)); this is not usual, please
just report (P<0.05) at the end of sentence for all of variables in the sentence. More details are
in table. Please observe it throughout the manuscript.
10- In the results section_ table 3; using Pearson correlation or Spearman one is not appropriate
since one of the variables (grade) has ordinal scale. Please use ANOVA test instead.
11- In the results section_ the term “adjusted Logistic regression” is not common term, please
remove “adjusted”.
12- In the results section_ table 4; the authors have conducted univariate analysis then
multivariate one without removing non-significant variables which obtained in univariate
analysis (P-value over 0.2). In multivariate model (adjusted OR) you should avoid putting non-
significant variables in model.
13- In the results section_ table 5; please make it clear to the readers what is dependent variable in
model before. Moreover, it seems the authors have used the grades of  NAFLD as the dependent
variable; in this case since you should apply ordinal regression model, not Logistic model. In
both tables, please check multicollinearity.
14- In the results section_ regarding the main study goals, it had better remove ROC analysis
and its table. It is a different subject.
15- In the discussion section; the sentence “…assessments and they accounted for 20.53% of
the total study population” Please determine the study population.
16- In the discussion section’ the authors have compared obtained prevalence rate with other
studies (e.g., Moghaddasifar et al) based on point estimate whilst they should compare their
findings based on confidence interval along with considering age and sex differences in studies,
as the study subjects. Please revise it.
17- In the discussion section; the authors have compared study results with some other case-
control studies; firstly, after revising statistical models it is possible to compare the findings
(please refer to above items), secondly, as you know, in case-control studies the probable risk
factors should be measured before disease occurrence while in this study they have measured
concurrently (having NAFLD and biomarker measures) please compare study results with
analytical cross-sectional studies.
18-  Further comments on discussion remained after requested revisions.
Sincerely,