Review for 10.1186/s12876-024-03579-z (2025)

Title: Association between the triglyceride-glucose index and liver fibrosis in adults with
metabolism-related fatty liver disease in the United States: a cross-sectional study of NHANES
2017–2020
Version: 1 Date: 16 Nov 2024
Reviewer:  Amira A A Othman
Reviewer's report:
First of all
I want to congratulate the authors on their work. In this study, Ying et al. used data from the
2017–2020 National Health and Nutrition Examination Survey (NHANES) for adult Americans.
This research aims to investigate the potential association between the triglyceride-glucose
(TyG) index and liver fibrosis (LF) in adult US citizens.
Non-alcoholic fatty liver disease (NAFLD) is recognized as the most prevalent chronic liver
disease, impacting about 30% of global individuals, with the potential to progress to advanced
hepatic fibrosis and end-stage liver diseases eventually [*]. In June 2023, a multi-society
committee of international experts was gathered, and new terminology was adopted to reduce
stigma and increase disease awareness [**]. A new terminology, Steatotic liver disease (SLD),
replaces “fatty liver disease” as the umbrella term. Under subgroups of SLD, NAFLD has been
renamed as metabolic dysfunction-associated Steatotic liver disease (MASLD) [**]. NAFLD/
MASLD is closely related to metabolic syndrome (MetS) and its associated components of
hypertension, type 2 diabetes mellitus, dyslipidemia, and obesity[***].
(*:doi: 10.1097/HEP.0000000000000004, **: doi: 10.1016/j.jhep.2023.06.003, ***  doi:
10.1111/apt.17308).
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.
2. Abbreviations must be fully written at their first appearance.
In Title:
3. The triglyceride-glucose (TyG) index should not be abbreviated in the research title.
4. The authors should consider indicating the age and locality at which the National Health and
Nutrition Examination Survey (NHANES) was performed.
I suggest “Association between the triglyceride-glucose index and liver fibrosis in US adult: a
cross-sectional study of NHANES 2017–2020”.
In Abstract section
5. “TyG index”, Please give more explanation in the introduction section.
6. In method: please use “Using data from the National Health and Nutrition Examination
Survey (NHANES) database spanning from 2017 to 2020, a cross-sectional study included (NO.)
participants was performed to assess the relationship …….”.
7. 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 ZJU index and
gallstones incidence. Fitted smoothing curves and threshold effect analysis were used to describe
the nonlinear relationship, etc.
8. Nothing was mentioned about the participant’s age, sex, ethnicity, etc.
9. The type of study: a population-based study.
10. Why did you choose to represent the 2017-2020 NHANES cycle, it begins from 2001 to
2020, shall expanding the cycles give more accurate findings?
In the Introduction section:
11. Try to provide a summarized description of The National Health and Nutrition Examination
Survey (NHANES) in the background 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.”.
12. Authors must give an account of Gallstones, one of the most prevalent digestive system
disorders in the world, the symptoms if present, the risk factors, the affection % in the American
population, etc.
(https://doi.org/10.3389/fnut.2024.1428488 ).
13.  Authors must give an account of the TyG index.
14. In contrast to NAFLD, MAFLD does not necessitate ruling out other liver disease causes,
such as viral hepatitis or heavy alcohol use*. The new name chosen to replace NAFLD reflected
the disease etiology better and conveyed a more practical approach in daily clinical practice than
NAFLD, considering its close association with metabolic syndrome**. Please discuss the new
nomenclature in more detail.
(*: Doi: 10.1016/j.jhep.2020.03.039, **: doi: 10.1097/HEP.0000000000000520)
In the Methods section:
15. Please move the sentences defining the NHANES to the introduction section rather than the
methodology section.
16. Please provide the participants' sociodemographic data.
17. What was the source of the covariate data?
18. How the sample size was calculated.
19. Inclusion and exclusion criteria are incomplete.
20. Reference for CAP and LS
21. Statistical analysis:
- Why did you choose mean ± standard deviation rather than mean ± standard error?
-  The Mann–Whitney U test / Wilcoxon rank-sum test: both are nonparametric and involve
the summation of ranks. The Mann–Whitney U test is applied to independent samples. The
Wilcoxon signed-rank test is applied to matched or dependent samples. T-test is used to compare
the mean of a continuous variable between a maximum of 2 groups. Why did you choose the
Wilcoxon rank-sum test?
- In logistic regression analyses, is it multivariate or univariate? Please identify.
- “Three logistic regression models were employed to investigate the independent relationship
between circadian syndrome and gallstones, 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 circadian syndrome and gallstone disease.
In the Results section:
22. 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.
23. 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).
24. Log2 logarithmic transformation shall be analyzed.
In the Discussion section:
25. 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.
26. The study ad its results were extensively studied, what are the novelty of your study?
- doi.org/10.3389/fendo.2022.1043169
- doi.org/10.1186/s12933-024-02343-7
- doi: 10.1016/j.clnesp.2021.04.025
- doi: 10.1186/s12902-022-01172-7
In the conclusion section:
27. The conclusion should restate your main points and provide closure.