Review for 10.1186/s12876-024-03538-8 (2024)

Title: The moderating effect of dietary fiber intake on the association between sleep pattern and
liver fibrosis in metabolic dysfunction-associated steatotic liver disease: a study from NHANES
Version: 0 Date: 22 Sep 2024
Reviewer:  Amira A A Othman
Reviewer's report:
First of all
I want to congratulate the authors on their work. In this study, Jia et al used data from the
2017–2020 National Health and Nutrition Examination Survey (NHANES) for Americans, this
research aims to explore the moderating effect of dietary fiber intake on the association between
sleep pattern and liver fibrosis in MAFLD patients in adult US citizens.
Recently, the influence of diet on health has garnered more attention. Research indicates
that consuming more dietary fiber, mainly from grains, fruits, and vegetables, correlates with
lower risks of hypertension, hyperuricemia, type 2 diabetes, cardiovascular diseases, and
cancer *, **. The link between dietary fiber consumption and NAFLD is being explored, with
inconsistent results. Some studies indicate lower dietary fiber consumption in NAFLD patients,
whereas others note no significant difference compared to non-NAFLD individuals***. Current
research on sleep stage changes in NAFLD patients shows inconsistent findings. Some studies
indicate a possible decrease in the percentage of rapid-eye-movement sleep in NAFLD patients.
Additionally, other studies suggest changes in non-rapid eye movement sleep structure, such as
a potential decrease in the proportion of slow wave sleep. Further large-scale research is needed
to gain a better understanding of these sleep characteristics in NAFLD patients****.
(*: doi: 10.3390/nu14132650, ** doi.org/10.1186/s12967-022-03558-6, ***: doi.org/10.1186/
s12876-024-03256-1, ****: doi: 10.4254/wjh.v16.i3.304).
The authors tried to contribute to this field of research with new findings, nevertheless, there is
an observation for which sufficient justification must be obtained.
In general:
1. The English writing level is shallow, and it is necessary to seek help from an English language
specialist to correct spelling and grammatical errors in the entire text.
In Title:
2. The authors may consider indicating that the study is an insight from NHANES and the locality
at which the National Health and Nutrition Examination Survey (NHANES) was performed.
3. “Non-alcoholic fatty liver disease (NAFLD)” is a broad expression that encompasses a
variety of conditions, including “non-alcoholic fatty liver (NAFLD, steatosis)”, intrahepatic
lipid accumulation without any secondary cause of liver fat accumulation such as heavy alcohol
consumption, of at least 5% of the liver weight that causes liver dysfunction and inflammation,
and advance to “non-alcoholic steatohepatitis (NASH)”, which is distinguished by liver fibrosis,
which advances to cirrhosis, and hepatocellular carcinoma in about 30–40% of cases. Thus, the
disease spectrum of MASLD includes simple steatosis, steatohepatitis, fibrosis, and cirrhosis.
Which of them is the scope of your study to be identified in the title?
In Abstract section
4. The background subsection:
-  Should be the shortest part of the abstract. It should very briefly outline the following
information: What is already known about the subject, related to the paper in question. What is
not known about the subject and hence what the study intended to examine (or what the paper
seeks to present). Please reconstruct it properly.
5.  The type of study: a population-based study.
6. In method subsection:
- please use “Using data from the National Health and Nutrition Examination Survey (NHANES)
database spanning from 2017 to 2020, a cross-sectional study included ***** participants was
performed to assess the relationship …….”.
- It would help if you described the aim of your statistical analysis. For example, Multivariate
linear regression models were used to examine the linear connection between sleep patterns,
dietary fiber intake, with liver fibrosis. Fitted smoothing curves and threshold effect analysis
were used to describe the nonlinear relationship, etc.
- A two-part linear regression model was also used to estimate threshold effects.
- Nothing was mentioned about the participant’s age, sex, etc. in the abstract.
7. In conclusion subsection
- State the conclusion concisely and avoid overstatements: Dietary fiber intake affect/not affect
……,
- Guidance for further investigations should not be here.
In the Introduction section:
8. Try to provide a summarized description of The National Health and Nutrition Examination
Survey (NHANES) in the background section rather than in the methodology section. You may
use the following
“NHANES (www.cdc.gov/nchs/nhanes) is designed to assess the health and nutritional status
of adults and children in the United States. The survey is distinctive in that it incorporates
both physical examinations and interviews. Several cross-sectional, nationally representative
health examination surveys are part of the NHANES program. Questions about demographics,
health insurance status, dietary habits, acute and chronic medical issues, mental health, and
prescription drug use are all included in the health interview. Exam components can change
between survey cycles but typically include blood pressure, dental exams, vision, hearing,
dermatology, fitness, balance and strength testing, respiratory testing, taste and smell, and
body measurements (weight, height, skin folds, body composition scans). Hematology, organ
and endocrine function (e.g., thyroid, kidney), environmental exposure, dietary biomarkers,
metabolic and cardiovascular health, and infectious disease are a few examples of laboratory
components.”.
9. Non-alcoholic fatty liver disease (NAFLD) nomenclature had several limitations, the name
chosen to replace NAFLD is metabolic dysfunction-associated steatotic liver disease (MASLD)
(Ref: doi.org/10.1186/s12876-024-03310-y).
10. Please focus on the relationship between the effect of dietary fiber intake on the association
between sleep pattern and liver fibrosis in MAFLD patients more than its relationship with
cardiovascular disorders.
In the Methods section:
11. Please move the sentences defining the NHANES to the introduction section rather than the
methodology section.
12. What was the source of the covariate data?
13. Statistical analysis:
- Continuous variables were presented as mean and standard error (SE):
- Why did you choose mean ± standard error rather than mean ± standard deviation?
-  The Mann–Whitney U test is a nonparametric test and involves the summation of ranks. The
Mann–Whitney U test is applied to independent samples. T-test is used to compare the mean of
a continuous variable between a maximum of 2 groups. Why did you choose the T-test?
- According to Table 2: Please discuss the following : “Three logistic regression models were
employed to sleep pattern, dietary fiber intake, with liver fibrosis in MAFLD patients, with
varying levels of adjustment for potential confounders. Model 1 was unadjusted for covariates,
while Model 2 included adjustments for age, sex, and race. Model 3 was further adjusted
for education, marital status, PIR, BMI, alcohol intake, smoking status, physical activity,
hypertension, diabetes, high cholesterol levels, coronary heart disease, stroke, and cancer.”
Could you please explain how covariates were categorized? Why such diseases were excluded
(hypertension, diabetes, high cholesterol levels, coronary heart disease, stroke, and cancer)?
- The generalized additive model and smoothed curve testing should be used to assess the
nonlinear relationship between sleep patterns, and dietary fiber intake, with liver fibrosis in
MAFLD patients.
In the Results section:
14. In Tables: You can title the statistical test column as “Test of significance” and use U= for
the Mann–Whitney U test, T= for the T-test, and #2 = for the Chi-square test, etc.
15. Subgroup analyses must be performed to evaluate the effect of circadian syndrome on
gallstones and their stability in different populations. Subgroup analyses based on differences
in diagnostic components were performed to elaborate correlations. The results were presented
in forest plots using odds ratios (ORs) and 95% confidence intervals (CIs).
16. What about Quartile cut-off values?
17. Log2 logarithmic transformation shall be analyzed.
18. Future article readers may not know whether the above-mentioned variables were originally
collected as continuous data during data collection by NHANES, or whether the data were
originally categorized in the current study. In addition, in case there is a methodology article
published by NHANES or by other authors that specifically describes the variables, the authors
of the current study may consider citing that paper in the methodology section where the authors
of the current study mentioned the NHANES website.
In the Discussion section:
19. The discussion section is one of the final parts of a research paper, in which an author
describes, analyzes, and interprets their findings. They explain the significance of those results
and tie everything back to the research question(s). In this manuscript, there is confusion between
what should be written in the introduction section and the discussion section. Please reconstruct
the discussion section.
20. Discuss the novelty of your study in the notion of others (doi.org/10.3389/
fnut.2024.1446694,  doi.org/10.1186/s12876-024-03256-1, doi: 10.2147/DMSO.S198744, doi:
10.3389/fpubh.2022.1038435). Some studies indicate lower dietary fiber consumption in
NAFLD patients, whereas others note no significant difference compared to non-NAFLD
individuals. Current research on sleep stage changes in NAFLD patients shows inconsistent
findings. Some studies indicate a possible decrease in the percentage of rapid-eye-movement
sleep in NAFLD patients. Additionally, other studies suggest changes in non-rapid eye
movement sleep structure, such as a potential decrease in the proportion of slow wave sleep.
Further large-scale research is needed to gain a better understanding of these sleep characteristics
in NAFLD patients.
21. Limitations and Strengths should be mentioned.
22. Diseases diagnosis depending only on a questionnaire is to be considered one of the main
weaknesses.
In the conclusion section:
23. The conclusion should restate your main points and provide closure.