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. 2025 Aug 1;20(8):e0328415. doi: 10.1371/journal.pone.0328415

Non-linear association of cardiometabolic index with gallstone disease in US adults: A cross-sectional study

Zhe Xiong 1,#, Qiuyue Sun 1,2,#, Jin Huang 1, Fengdong Li 1,*
Editor: Qian Wu3
PMCID: PMC12316293  PMID: 40748974

Abstract

Objective

Obesity and disorders of lipid metabolism are key factors in gallstone formation. The cardiometabolic index (CMI) is a new marker combining obesity indicators (WHtR) and lipid levels (TG/HDL-C). The aim of this study was to investigate whether CMI is associated with the prevalence of gallstone disease (GSD) in adults.

Methods

This study was a cross-sectional study by cohort data from the National Health and Nutrition Examination Survey (NHANES) January 2017-March 2020 cycle. Using sample-weighted multivariate logistic regression analysis, sample weighted restricted cubic spline (RCS), the receiver operating characteristic (ROC) and subgroup analysis to assist us with gaining insight into the association between CMI and GSD.

Results

Among the 2825 included participants, 307 of them were patients with GSD. In a model adjusting for multiple covariates, each unit increase in CMI increased the odds of GSD by 16% (OR = 1.16; 95% CI = 1.04-1.30; P = 0.015). Compared to participants with the lowest CMI, those with the highest index had a significantly increased risk of GSD (OR = 2.52; 95% CI = 1.45-4.36; P = 0.006). The sample-weighted multivariable adjusted RCS revealed a nonlinear relationship between CMI and GSD. ROC analysis revealed that CMI had a high predictive effect on the diagnosis of GSD (AUC = 0.680). Subgroup analysis suggested the influence of gender differences on the relationship between CMI and GSD.

Conclusions

The present study found that elevated CMI significantly increased the risk of GSD and emphasized the non-linear relationship between both. These results suggest that CMI could be a potential marker for early screening and intervention of GSD, thus providing guidance for future clinical management of GSD.

Introduction

Gallstone disease (GSD) as one of the most common digestive disorders, it is present in populations all over the world [1,2]. The prevalence and incidence of GSD have been reported to be approximately 15% and 0.6% per year, respectively. The prevalence of gallstones increases with age, and it is more prevalent among women than among men [35]. Gallstones can be located anywhere in the biliary system and are mainly categorized as cholecystolithiasis, calculus of extrahepatic bile duct and hepatolithiasis [1]. Most patients with GSD are asymptomatic, but when gallstones enter the bile ducts and cause obstruction, the patient experiences typical biliary colic, mostly accompanied by nausea and vomiting [4]. Approximately 1% to 4% of symptomatic patients with GSD develop serious complications, such as acute cholecystitis, gallstone pancreatitis, Mirizzi syndrome, and gallstone ileus [68]. In addition, long-term stimulation by gallstones and inflammation may increase the risk of gallbladder cancer incidence [9,10]. In the U.S., more than 800,000 cholecystectomies are performed each year, costing nearly $6.5 billion annually, making GSD a major global health concern [11]. Therefore, it is crucial to find accurate and reliable clinical indicators in order to provide new insights for early screening and intervention of GSD.

According to previous studies, risk factors for GSD include age, female gender, pregnancy, unhealthy lifestyle, and inflammatory diet [1214]. one of the key factors contributing to the formation of gallstones is obesity [5]. It is always known that visceral fat plays a supporting, stabilizing and protective role for the internal organs of the body [15]. However, excessive accumulation of visceral fat can lead to metabolic disorders related to obesity, such as insulin resistance, glucose intolerance and dyslipidemia, which undoubtedly increase the risk of gallstone disease [1618]. Multiple studies have clearly demonstrated that obesity significantly increases the risk of gallstones and have emphasized the important role of novel anthropometric indices in the prevention of gallstones [19,20]. In addition, disorders of lipid metabolism in the body also promote the gallstones formation. Triglyceride (TG), as the lipid component of blood lipids, is an important product of lipid metabolism, and an increase in serum TG can induce a variety of metabolism-related diseases. However, high-density lipoprotein cholesterol (HDL-C) transports cholesterol from surrounding tissues, which is then converted to bile acids or excreted directly from the intestine via bile [21]. Normally, cholesterol, lecithin, and bile salts in bile work together to stabilize the bile. As TG increases or HDL decreases, cholesterol becomes supersaturated, causing cholesterol crystals to precipitate to form stones [22]. Studies have shown that serum HDL levels are inversely and linearly related to risk of gallstone. However, the risk of gallstones increases with increasing serum TG levels [23]. Although many studies have suggested a strong association between obesity and lipid metabolism and GSD, there is still a lack of reliable clinical indicators to manage the occurrence of gallstones.

The cardiometabolic Index (CMI) is a new index calculated from waist-to-height ratio (WHtR), triglycerides, and high-density lipoprotein cholesterol [24]. In contrast to previous body roundness index (BRI) and lipid accumulation product (LAP) indicators, CMI provides a more complete picture of the body’s metabolic state through an individual’s degree of obesity and lipid levels and has been found to have better predictive potential in some studies [2527]. As the study evolved, researchers found that CMI could not only assess heart health status it could also be used to predict the presence and severity of metabolic syndrome in adult obese patients [28]. Furthermore, elevated CMI has been demonstrated to be significantly associated with insulin resistance and type 2 diabetes [29]. Based on the above findings, it is considered that metabolic syndrome (MetS) and insulin resistance are thought to be associated with an increased risk of gallstones [30,31]. Therefore, the present study hypothesized that metabolic abnormalities reflected by changes in CMI may influence the occurrence of gallstones. This study, with data from the National Health and Nutrition Examination Survey (NHANES), illustrates the relationship between CMI and GSD in U.S. adults for the first time, ultimately providing additional guidance on the clinical management of GSD and offering important insights for future research.

Methods

Study population and research design

The NHANES program was committed to collecting comprehensive data regarding the health and nutrition status of the American population, as well as relevant health behavior information. It covered demographics, dietary, examination, laboratory, and questionnaire data. Visit http://www.cdc.gov/nhanes to access more information about NHANES.

There were 15,560 participants enrolled in this study between January 2017 and March 2020, of whom 9232 were adults aged ≥ 20. However, 5,483 participants lacking CMI data and 6 participants lacking GSD data were excluded. Moreover, 918 participants were excluded because they did not have data on education status, poverty to income ratio (PIR), body mass index (BMI), smoking, alcohol consumption, hypertension, diabetes, cancer, and coronary heart disease (CHD). Fig 1 illustrated the flowchart of the screening process of the present study.

Fig 1. The flowchart of participants selection.

Fig 1

NHANES: National Health and Nutrition Examination Survey; CMI: cardiometabolic index.

Cardiometabolic index

Reference to previously published study [24], information on fasting TG and HDL in CMI was obtained from laboratory data, and information on waist circumference (WC) and height was obtained from measurement data. The specific calculations are as follows:

WHtR = waist circumference (cm)/height (cm)
CMI = TG (mmol/L)/HDL-C (mmol/L) × WHtR

Assessment of gallstone

Questionnaires from the NHANES data were used for the diagnosis of gallstones. The questionnaire, “Have you been told by a doctor or other health professional that you have gallstones?” was used to indicate the presence of gallstones when the participant answered “yes”.

Covariables

Several covariates were also included in this study for statistical analysis, as they may be potential confounding factors affecting the relationship between CMI and GSD. Confounding factors that were included age, gender, race, education level, PIR, and BMI. Smoking more than 100 cigarettes during one’s lifetime was identified as smoking status. Ever have 4/5 or more drinks every day was identified as drinking status. The results for total cholesterol (TC) were obtained from laboratory data. Definition of physical activity, hypertension, diabetes, cancer, and CHD were obtained from questionnaires or clinical diagnosis.

Statistical analysis

To ensure the reliability of the population estimates, this study processed the data according to sample weight recommended by NHANES. In the analysis of continuous variables, the researchers used the weighted mean and standard deviation (SD), and in the analysis of categorical variables, they used the weighted percentages. CMI was grouped into quartiles based on the characteristics of continuous variables. The Kruskal-Wallis H-test or chi-square test was applied to compare the differences between quartile groupings of CMI. Weighted multivariate logistic regression models were constructed to evaluate the relationship between CMI and GSD using the odds ratio (OR) and 95% confidence interval (CI). Logistic regression is a generalized linear model used for addressing classification problems, and it can intuitively reflect the impact of changes in CMI on the risk of GSD. The crude model (Model 1) was not adjusted. Age, sex, and race were accounted for in Model 2. Based on Model 2, Model 3 had adjustments for education level, PIR, physical activity, smoking status, drinking status, TC, hypertension, diabetes mellitus, cancer, and CHD. The adjustment did not account for BMI, as it had a substantial impact on exposure. Additionally, we further analyzed the nonlinear relationship between CMI and the prevalence of GSD using restricted cubic splines (RCS), generalized additive models (GAM), and smooth curve fitting. RCS is a method used for modeling nonlinear relationships; it segments the values of the independent variable and employs cubic spline functions within each interval for modeling. Therefore, RCS can effectively capture the complex relationship between CMI and GSD. Subsequently, the receiver operating characteristic (ROC) curve was used to calculate the area under curve (AUC) value to assess the diagnostic value of the CMI index for GSD. Finally, subgroup analyses were conducted to test for interactions between CMI and specific covariates. Statistical significance was determined at a threshold of P < 0.05 during the statistical analysis. The statistical analyses conducted in this study were conducted using R version 4.3.1.

Results

Baseline characteristics

After screening, the analysis encompassed a total of 2,825 participants. Table 1 presents the baseline characteristics of the study population by CMI quartiles. As indicated in the table, there were significant differences in CMI quartiles by age, gender, race, education level, PIR, BMI, hypertension, diabetes, and TC (P < 0.05). The increase in CMI was associated with an increase in the proportion of Mexican Americans, an increase in the proportion less than high school, and a decrease in annual household income. It is noteworthy that in the highest quartile there is a higher proportion of males than females (62.16% vs. 37.8%), with the proportion of males showing an upward trend in the quartiles, while the opposite is true for females. As CMI increased, BMI of the participants also increased. In addition, the prevalence of hypertension and diabetes also increased with increasing CMI. A significant correlation between CMI quartiles and gallstone prevalence without adjustment for covariates (P = 0.030).

Table 1. The baseline characteristics of the study population by CMI quartiles in the logistic regression model.

Characteristic Total Quartiles of Cardiometabolic index (CMI) P value
(N = 2825) Q1 (N = 707) 0.027-0.255 Q2 (N = 706) 0.255-0.459 Q3 (N = 704) 0.459-0.816 Q4 (N = 708) > 0.816
Age (years) 47.72 ± 0.76 43.03 ± 1.40 48.93 ± 0.89 49.99 ± 1.21 49.38 ± 0.94 < 0.001
Gender (%) < 0.001
 Male 1449 (50.13%) 306 (41.63%) 347 (46.93%) 365 (49.77%) 431 (62.16%)
 Female 1376 (49.87%) 401 (58.37%) 359 (53.07%) 339 (50.23%) 277 (37.84%)
Race (%) < 0.001
 Mexican American 359 (8.67%) 57 (6.17%) 82 (7.71%) 86 (9.32%) 134 (11.58%)
 Other Hispanic 269 (6.27%) 50 (4.77%) 69 (7.29%) 72 (7.28%) 78 (5.97%)
 Non-Hispanic White 1069 (66.02%) 254 (67.87%) 250 (65.89%) 250 (59.91%) 315 (69.52%)
 Non-Hispanic Black
 Other Race
695 (10.18%)
433 (8.86%)
232 (13.36%)
114 (7.83%)
204 (11.63%)
101 (7.48%)
181 (11.73%)
115 (11.76%)
78 (4.20%)
103 (8.73)
Education level (%) 0.004
 Less than high school 459 (9.24%) 71 (5.56%) 96 (7.84%) 129 (10.94%) 163 (12.87%)
 High school or GED 673 (25.22%) 163 (21.66%) 169 (24.50%) 171 (26.61%) 170 (28.35%)
 Above high school 1693 (65.54%) 473 (72.78%) 441 (67.66%) 404 (62.45%) 375 (58.78%)
PIR 3.20 ± 0.07 3.45 ± 0.10 3.23 ± 0.12 3.10 ± 0.11 3.00 ± 0.10 0.008
BMI (kg/m2) 29.78 ± 0.20 24.94 ± 0.21 28.91 ± 0.40 31.55 ± 0.38 34.04 ± 0.38 < 0.001
Alcohol (%) 0.189
 Yes 442 (14.13%) 98 (11.16%) 114 (14.84%) 105 (13.21%) 125 (17.28%)
 No 2383 (85.87%) 609 (88.84%) 592 (85.16%) 599 (86.79%) 583 (82.72%)
Smoked (%) 0.274
 Yes 564 (17.31%) 127 (13.69%) 149 (17.93%) 135 (19.38%) 153 (18.62%)
 No 2261 (82.69%) 580 (86.31%) 557 (82.07%) 569 (80.62%) 555 (81.38%)
Physical activity (%) < 0.001
 Yes 1394 (58.11%) 418 (69.54%) 360 (57.79%) 317 (55.74%) 299 (48.82%)
 No 1431 (41.89%) 289 (30.46%) 346 (42.21%) 387 (44.26%) 409 (51.18%)
Hypertension (%) < 0.001
 Yes 1277 (38.13%) 220 (22.33%) 304 (36.16%) 371 (46.14%) 382 (49.21%)
 No 1548 (61.87%) 487 (77.67%) 402 (63.84%) 333 (53.86%) 326 (50.79%)
Diabetes (%) < 0.001
 Yes 491 (11.92%) 40 (2.53%) 101 (8.21%) 142 (13.15%) 208 (23.96%)
 No 2334 (88.08%) 667 (97.47%) 605 (91.79%) 562 (86.85%) 500 (76.04%)
CHD (%) 0.053
 Yes 130 (3.68%) 14 (2.03%) 32 (4.04%) 35 (3.41%) 49 (5.28%)
 No 2695 (96.12%) 693 (97.97%) 674 (95.96%) 669 (96.59%) 659 (94.72%)
Cancers (%) 0.207
 Yes 307 (11.76%) 68 (10.33%) 84 (13.50%) 64 (9.47%) 91 (13.51%)
 No 2518 (88.24%) 639 (89.67%) 622 (86.50%) 640 (90.53%) 617 (86.49%)
Gallstones (%) 0.030
 Yes 307 (11.69%) 35 (6.45%) 76 (12.23%) 93 (12.95%) 103 (15.44%)
 No 2518 (88.31%) 672 (93.55%) 630 (87.77%) 611 (87.05%) 605 (84.56%)
WC (cm) 100.79 ± 0.49 87.43 ± 0.467 99.35 ± 0.85 105.17 ± 0.82 112.00 ± 1.04 < 0.001
TC (mmol/L) 4.79 ± 0.05 4.53 ± 0.07 4.78 ± 0.07 4.88 ± 0.06 4.99 ± 0.08 < 0.001
TG (mmol/L) 1.26 ± 0.03 0.56 ± 0.01 0.89 ± 0.014 1.26 ± 0.01 2.32 ± 0.08 < 0.001
HDL (mmol/L) 1.39 ± 0.02 1.77 ± 0.03 1.46 ± 0.02 1.27 ± 0.01 1.05 ± 0.01 < 0.001

Mean ± SD for continuous variables, the P value was calculated by weighted linear regression; frequency percentages for categorical variables, the P value was calculated by weighted chi-square test. PIR: poverty-to-income ratio; BMI: Body Mass Index; CHD: coronary heart disease; CMI: cardiometabolic index; WC: Waist circumference; TG: Triglycerides; TC: Total cholesterol; HDL: High-density lipoprotein cholesterol.

Association between the CMI index and GSD

To provide insight into the potential link between CMI and GSD, the sample-weighted multivariate logistic regression models were constructed (Fig 2) (S1 Table). As shown in this table, when CMI was analyzed as a continuous variable, the prevalence of GSD was significantly correlated with CMI. (OR = 1.16; 95% CI = 1.04–1.30; P = 0.015) under model 3, which considered all relevant covariates. This suggested that for every unit increase in CMI, the odds of GSD increased by 16%. Next, CMI was further categorized into quartiles to describe the correlation. In model 3, Participants in the highest quartile (Q4) of CMI increased the risk of developing GSD by 152% (OR = 2.52; 95% CI = 1.45–4.36; P = 0.006) compared to those in the lowest quartile (Q1), and this positive correlation remains significant in both Model 1 and Model 2 species. Furthermore, the results of trend analysis for all three models were statistically significant (P for trend < 0.05). This indicated that as CMI increases, the prevalence of GSD is higher. Finally, the sample-weighted multivariable adjusted RCS revealed a statistically significant nonlinear relationship between CMI and GSD (P nonlinear = 0.0121) (Fig 3). Additionally, generalized additive models and smooth curve fitting showed a nonlinear relationship between CMI and OAB (log-likelihood ratio test P value < 0.001) (Table 2).

Fig 2. Association between CMI and gallstone disease (GSD) in NHANES 2017-2020, weighted.

Fig 2

Model 1: unadjusted. Model 2: age, sex and race were adjusted. Model 3: age, sex, race, education level, PIR, smoking status, drinking status, physical activity, total cholesterol, hypertension, diabetes, cancer, and coronary heart disease were adjusted. CMI: cardiometabolic index; OR: odds ratio; 95% CI: 95% confidence interval.

Fig 3. The restricted cubic spline for the association between CMI and gallstone.

Fig 3

Table 2. Threshold effect analysis of the association between CMI and female gallstone disease (GSD) prevalence.

Outcome: GSD Adjusted OR (95%CI) P value
Fitting by standard linear model 0.013 (0.001, 0.025) 0.036
Fitting by two-piecewise linear model
Inflection point 0.561
CMI < 0.561 0.165 (0.09, 0.239) <0.001
CMI > 0.561 0.003 (−0.01, 0.016) 0.668
Logarithmic likelihood ratio test P value < 0.001

The associations were adjusted for age, sex, race, education level, PIR, smoking status, drinking status, physical activity, total cholesterol, hypertension, diabetes, cancer, and coronary heart disease.

Diagnostic value of CMI index for GSD

ROC curves were further plotted to assess the diagnostic value of CMI and its components for GSD. As shown in Fig 4 in diagnosing GSD, CMI has the highest accuracy with an AUC of 0.680. The other indices with diagnostic values in descending order were WHtR (AUC = 0.646) and TG/HDL (AUC = 0.570).

Fig 4. The ROC curve of CMI, TG/HDL and WHtR for the diagnosis of gallstones.

Fig 4

Subgroup analysis

Completely adjusted multivariate logistic regression analyses were used for each subgroup to assess that the association between CMI and GSD was robust across age, sex, education level, smoking, alcohol consumption, hypertension, diabetes, cancer, and CHD stratification. As shown in S2 Table and Fig 5, the positive correlation between CMI and gallstones was robust in all subgroups (P for interaction > 0.05) except in the gender subgroup (P for interaction = 0.015).

Fig 5. Subgroup analysis between CMI and gallstone disease (GSD).

Fig 5

Note: All covariates (as in Model 3) were adjusted except the stratification variable itself. CMI: cardiometabolic index; OR: odds ratio; 95% CI: 95% confidence interval.

Discussion

Through cross-sectional analysis of NHANES data, we discovered that the prevalence of GSD was substantially and positively correlated with CMI. In the fully adjusted model, the risk of GSD increased by 152% for each unit increase in CMI, as indicated by the results of this study. In all three models, A trend test produced significant significance, indicating a dose-response relationship between CMI and GSD. Also, the RCS confirmed there is a nonlinear association between the two. Moreover, the ROC analysis highlighted the promising diagnostic value of CMI in the diagnosis of GSD. Subgroup analysis and interaction testing demonstrated that the association between CMI and GSD was steady in age, education level, smoking, alcohol consumption, hypertension, diabetes, cancer, and CHD. In summary, CMI may be regarded as an effective tool for screening high-risk groups for GSD, which is important for early intervention and personalized treatment of GSD.

The CMI, as an indicator to assess the degree of obesity and lipid levels in an individual, was thought to provide a better insight into the body’s metabolic status. In previous studies, obesity resulted disorders of lipid metabolism and excessive accumulation of cholesterol, which were important mechanisms for gallstone formation [21,32]. As a result, obesity is universally acknowledged as a concrete risk factor for gallstones. Furthermore, a study from a health check-up cohort of Chinese adult emphasized that obesity promoted gallstones development by investigating the association between metabolically health obesity (MHO) and gallstones [12]. Several anthropometric measures reflecting obesity, such as BMI, WC, and WHtR, have been demonstrated to be independently linked to the occurrence of gallstones [33]. Furthermore, the triglyceride glucose-waist height ratio (TyG-WHtR) was superior to triglyceride glucose-body index mass (TyG-BMI) and triglyceride glucose-waist circumference (TyG-WC) in identifying gallstone risk in a new indicator for assessing insulin resistance [34]. Similarly, obesity affects cholesterol metabolism, which is a key part of gallstone formation. Some serum lipid markers have been shown to be important factors in gallstone risk. Based on a multicenter study and meta-analysis, Zhang et al. found that both low HDL cholesterol levels and high TG levels were risk factors for gallstone [23]. In addition, multivariate Mendelian randomization analysis also revealed that serum TG was an independent risk factor to gallstones, and lowering TG also lower the risk of gallstones [35].

To date, the association of CMI with metabolism-related diseases had been elaborated in numerous literatures. On the one hand, CMI was pointed out to have better predictive potential in identifying MetS in U.S. adults [28]. On the other hand, higher CMI was associated with an increased prevalence of NAFLD and exacerbation of liver fibrosis [36]. However, there were no research that explored the association between CMI and GSD. Therefore, the prospective association between CMI and GSD was first disclosed in this study using NHANES data. The present study, the sample-weighted multivariate logistic regression models suggested a significant positive association between CMI and the risk of developing GSD and demonstrated a nonlinear relationship. These findings are beneficial for identifying asymptomatic GSD patients in clinical practice. Given that waist-to-height ratio and lipid profiling are routine examinations, CMI is far more accessible compared to abdominal ultrasound. Therefore, CMI can serve as a novel and convenient indicator for GSD prevalence and may assist clinicians in determining whether patients should undergo abdominal ultrasound screening in the future. Additionally, interaction tests revealed that the association between CMI and gallstones exhibited statistically significant variations across subgroups stratified by age, sex, alcohol consumption, smoking status, hypertension, diabetes mellitus, cancer, and CHD. The findings highlight that a higher CMI is associated with an elevated prevalence of GSD in females. This may be attributed to higher estrogen levels in women, which promote cholesterol deposition and influence gallstone formation. In animal experiments, GPER antagonists prevented estrogen-induced cholesterol stone formation in female mice [37]. Based on the results of an epidemiologic survey, estrogen therapy in menopausal women significantly increases the risk of symptomatic gallstones and cholecystectomy [38]. However, the clinical relevance of identifying emergent GSD using the CMI is extended by acknowledging the significant relationship between GSD and CVD, probably due to common causal pathways, as established through meta-analysis and meta-regression [39]. In conclusion, all these reports further prove the credibility of the findings of this research.

Regarding the potential mechanism between CMI and GSD, we first hypothesized that it could be attributed to inflammation and oxidative stress. Adipose tissue secretes a diverse array of inflammatory factors in addition to its function as an energy storage and organ protection, such as IL-1β, TL-6 and TNF-α[40]. These inflammatory factors can lead to gallstone formation by directly affecting the contractile function of gallbladder epithelial cells [41]. Furthermore, reactive oxygen species (ROS) produced during the inflammatory process mediate gallbladder epithelial cell damage, thereby promoting cholecystitis and gallstones [42]. Second, immune cell infiltration may also be the mechanism by which lipid accumulation leads to GSD. Adipose tissue contains a large number of immune cells who are able to regulate adipocyte function by secreting a variety of factors under physiological and pathological conditions [40]. Accumulation of adipose tissue macrophages (ATM) has been reported to affect cholesterol metabolism in obese states [43,44]. Besides, the researchers found that inhibiting the formation of neutrophil extracellular traps (NETs) was effective in suppressing crystal aggregation in bile [45,46]. Third, adipose tissue induced insulin resistance is similarly a key factor for stone formation. In the liver, insulin resistance promotes cholesterol secretion through ABCG5/8 induced aberrant expression of FOXO1 [47]. The above studies provided further strong evidence that CMI has a positive correlation with an elevated risk of GSD in terms of pathological mechanisms.

This investigation boasts numerous noteworthy advantages: first, this research considered the sample-weighted design from the NHANES database, which is nationally representative. Second, covariates that could potentially influence the relationship between CMI and GSD were appropriately adjusted to ensure the accuracy of the results. Third, subgroup analysis of the population was conducted in this study and further validated the stability of the results. However, we accept that the current study is subject to certain inherent limitations. First, the causative relationship between CMI and GSD could not be ascertained since this investigation was predominantly founded on a cross-sectional study. Second, due to the limitations of the NHANES database, we were unable to include all potential confounding factors that may influence the relationship between CMI and GSD, such as dietary habits and genetic predisposition. Lastly, we must emphasize that the outcome variable and some covariates in this study are based on self-reported data, which may introduce recall bias. Therefore, the findings of this study require validation through longitudinal research.

Conclusions

In summary, the current investigation revealed that the higher CMI was strongly associated with higher prevalence of GSD and confirmed a nonlinear relationship between the two. Subgroup analyses indicate that the association varies between the genders. These findings may help physicians to screen for people at risk of GSD and highlight the importance of taking gender differences into account when delivering personalized interventions for accurate gallstone prevention.

Supporting information

S1 Table. Association between CMI and gallstone disease (GSD) in NHANES 2017–2020, weighted.

(DOCX)

pone.0328415.s001.docx (13.2KB, docx)
S2 Table. Subgroup analysis between CMI and gallstone disease (GSD).

(DOCX)

pone.0328415.s002.docx (13.2KB, docx)

Data Availability

All data used for analysis in the study are available from https://figshare.com, DOI: https://10.6084/m9.figshare.28323725.

Funding Statement

This work was supported by the Fund of Changzhou Medical Center, Nanjing Medical University (CMCC202209 and CMCM202310). The funder of this work is Jin Huang, who participated in the Data curation and Formal Analysis of this study.

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Decision Letter 0

Qian Wu

PONE-D-24-47105Non-linear association of cardiometabolic index with gallstone disease in US adults: a cross-sectional studyPLOS ONE

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Reviewer #2: I Don't Know

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5. Review Comments to the Author

Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #1: This manuscript investigates the relationship between the Cardiometabolic Index (CMI) and gallstone disease (GSD) in U.S. adults. Using data from the National Health and Nutrition Examination Survey (NHANES) between 2017 and 2020, the study assesses whether CMI (a new composite indicator of obesity and lipid levels) associates non-linearly with GSD risk. The authors reveal that higher CMI correlates with an increased risk of GSD and propose that CMI might serve as a screening tool for GSD, with potential implications for clinical management.

In general, the manuscript is well-written and tables are clear. The authors use multiple ways (logistic regression, restricted cubic spline models, and subgroup analysis) to prove the positive correlation between CMI and GSD. The topic is beneficial to the clinical engagement and clearly suitable for publication in this journal. However, following issues need to be addressed before considering for publication.

1. This manuscript states they use logistics regression and restricted cubic spline models but haven’t provided any formulas or parameters deployed in this study. Need to address the rationale of choosing these two models for evaluating CMI – GSD correlation.

2. Lipid balance is crucial for gallstone disease, why choose CMI as indicator? Not [TG (mmol/L)/HDL-C (mmol/L)]? How does CMI compares to [TG (mmol/L)/HDL-C (mmol/L)] alone? And how does CMI compares to WHtR alone?

2. Lack visuals for logistics regression results and subgroup analysis.

3. Processed data (2825 out of 15,560) is not provided.

4. Although adjustments for multiple covariates were made, some potential confounders like diet habits, physical activity, and genetic predisposition are not accounted for. Discussing their potential impact on the results would improve the study's robustness.

5. Expand bias discussion (lack of other important factors as above). Address limitations of self-reported data -- could introduce recall bias. Highlight this as a limitation and consider suggesting longitudinal studies for validation.

6. Provide more insights on the subgroup analysis in the results, particularly regarding gender differences. Emphasize the clinical implications of gender-based variations in CMI's impact on GSD.

7. While the study indicates that CMI could be a screening tool, it may be helpful to discuss how CMI could complement existing GSD screening practices. Elaborate on how clinicians might integrate CMI in routine evaluations.

8. table 1: need to clearly indicate readers they are “logistic regression” models. The 4th “Q3” should be Q4.

9. figure 2 is too rough. It shows “figure 1” at the top left corner. Need more comprehensive captions explaining all elements including in the plot like the shade and cross-point. Enlarge x-axis and y-axis font size.

Reviewer #2: The present study demonstrates a nonlinear relationship between higher Cardiometabolic Index (CMI) and an increased risk of gallstone disease (GSD). However, there are several concerns regarding the methods used in the study that merit further consideration

Reviewer #3: This research is aligned with other research on cardiometabolic disease and liver disease such as GSD metabolic-associated fatty liver disease (MAFLD), applying different indices and statistical methods to test the association. The biological mechanism and underlying assumptions regarding the associations have been clearly defined previously, and possible co-variates/confounders have been identified, but the questions regarding which CM index is the most sensitive and specific clinical indicator for possible imminent liver disease in different populations residing in different environments and whether a valid universal threshold may be derived from the analyses if the association between the outcome and the index is not linear are not yet been answered. Although this study applied weighting in their analysis and adjusted for all relevant confounders in the multivariate logistic regression analyses, linearity was not observed. Restricted cubic spline analyses were thus performed to test for a ‘dose-dependent’ relationship, but failed to identify a threshold.

Some references that may be useful for the introduction, methodology or discourse are:

Global Epidemiology of Gallstones in the 21st Century: A Systematic Review and Meta-Analysis

Wang, Xin et al. Clinical Gastroenterology and Hepatology, Volume 22, Issue 8, 1586 – 1595

Zhang J, Liang D, Xu L, Liu Y, Jiang S, Han X, Wu H and Jiang Y (2024) Associations

between novel anthropometric indices and the prevalence of gallstones among

6,848 adults: a cross-sectional study. Front. Nutr. 11:1428488. doi: 10.3389/fnut.2024.1428488

Koyama, A. K., McKeever Bullard, K., Xu, F., Onufrak, S., Jackson, S. L., Saelee, R., Miyamoto, Y., & Pavkov, M. E. (2024). Prevalence of Cardiometabolic Diseases Among Racial and Ethnic Subgroups in Adults - Behavioral Risk Factor Surveillance System, United States, 2013-2021. MMWR. Morbidity and mortality weekly report, 73(3), 51–56. https://doi.org/10.15585/mmwr.mm7303a1

Duan S, Yang D, Xia H, Ren Z, Chen J, Yao S. Cardiometabolic index: A new predictor for metabolic associated fatty liver disease in Chinese adults. Front Endocrinol (Lausanne). 2022 Sep 16;13:1004855. doi: 10.3389/fendo.2022.1004855. PMID: 36187093; PMCID: PMC9523727.

Yan, L., Hu, X., Wu, S. et al. Association between the cardiometabolic index and NAFLD and fibrosis. Sci Rep 14, 13194 (2024). https://doi.org/10.1038/s41598-024-64034-3. https://rdcu.be/d0CD1

Song, Jimei, Yimei Li, Junxia Zhu, Jian Liang, Shan Xue, and Zhangzhi Zhu. "Non-linear Associations of Cardiometabolic Index with Insulin Resistance, Impaired Fasting Glucose, and Type 2 Diabetes among US Adults: A Cross-sectional Study." Frontiers in Endocrinology 15, (2024): 1341828. Accessed November 18, 2024. https://doi.org/10.3389/fendo.2024.1341828.

Lazzer, S., D'Alleva, M., Isola, M., De Martino, M., Caroli, D., Bondesan, A., Marra, A., & Sartorio, A. (2023). Cardiometabolic Index (CMI) and Visceral Adiposity Index (VAI) Highlight a Higher Risk of Metabolic Syndrome in Women with Severe Obesity. Journal of clinical medicine, 12(9), 3055. https://doi.org/10.3390/jcm12093055

DS Prasad, Zubair Kabir, JP Suganthy, AK Dash & BC Das. (‎2013)‎. Appropriate anthropometric indices to identify cardiometabolic risk in South Asians. WHO South-East Asia Journal of Public Health, 2 (‎3-4)‎, 142 - 148. World Health Organization. Regional Office for South-East Asia. https://iris.who.int/handle/10665/329790

Yan Zheng, Min Xu, Yanping Li, Adela Hruby, Eric B. Rimm, Frank B. Hu, Janine Wirth, Christine M. Albert, Kathryn M. Rexrode, JoAnn E. Manson, and Lu Qi. Gallstones and Risk of Coronary Heart Disease: Prospective Analysis of 270 000 Men and Women From 3 US Cohorts and Meta-Analysis

Arteriosclerosis, Thrombosis, and Vascular Biology Volume 36, Number 9 https://doi.org/10.1161/ATVBAHA.116.307507

Indices:

LAP

Ebrahimi, M., Seyedi, S. A., Nabipoorashrafi, S. A., Rabizadeh, S., Sarzaeim, M., Yadegar, A., Mohammadi, F., Bahri, R. A., Pakravan, P., Shafiekhani, P., Nakhjavani, M., & Esteghamati, A. (2023). Lipid accumulation product (LAP) index for the diagnosis of nonalcoholic fatty liver disease (NAFLD): a systematic review and meta-analysis. Lipids in health and disease, 22(1), 41. https://doi.org/10.1186/s12944-023-01802-6

Triglyceride-glucose index:

Li, H., Zhang, C. Association between triglyceride-glucose index and gallstones: a cross-sectional study. Sci Rep 14, 17778 (2024). https://doi.org/10.1038/s41598-024-68841-6

Aksoy E, Ergenç Z, Ocak Ök, Ergenç H. Triglyceride-Glucose Index is a Reliable Predictor of Metabolic Disorder in Gallstones. Bezmialem Science. 2024 Jul;12(3):363-367. doi:10.14235/bas.galenos.2024.43043

Body roundness index (BRI):

Wei C, Zhang G. Association between body roundness index (BRI) and gallstones: results of the 2017-2020 national health and nutrition examination survey (NHANES). BMC Gastroenterol. 2024 Jun 5;24(1):192. doi: 10.1186/s12876-024-03280-1. PMID: 38840060; PMCID: PMC11155175.

The threshold for risk assessment:

Eastwood, S. V., Hemani, G., Watkins, S. H., Scally, A., Davey Smith, G., & Chaturvedi, N. (2024). Ancestry, ethnicity, and race: explaining inequalities in cardiometabolic disease. Trends in molecular medicine, 30(6), 541–551. https://doi.org/10.1016/j.molmed.2024.04.002

General comments

The strength of the manuscript lies in the accommodation of relevant confounders and the application of restricted cubic spline analyses as a novel approach to make sense of the non-linearity of the association between this specific outcome and index.

Consider making more detailed and stronger deductions from the observed results, e.g., the subgroup analyses that were conducted to test for interactions between CMI and specific covariates. What stood out was the preponderance of males rather than females in the highest quartile (62.16 vs 37.8%) and the increasing trend in male proportions across quartiles with a reversed trend in females. This may be highlighted as a novel finding.

Specific comments:

There are numerous syntax errors throughout that need attention.

The Lipid Accumulation Product (LAP) index is mentioned in a sub-title within the Results section. This is the only occurrence of the term. Please clarify its relevance, because the paragraph reports on the CMI and the formulas for the two indices’ calculation differ.

The first paragraph in the introduction addresses Gallstone disease in general. The references are rather outdated. Please consider replacing them or adding more recent references (some of which are included in the above list of references that may be of interest to the authors)

In the third paragraph of this section, the CMI is introduced. You may consider referring to other more recently applied indices and state why you chose the CMI. E.g., that it has better predictive potential, as alluded to in the discussion section You refer to some of these indices in the paragraph within the discussion section that starts with ‘The CMI, as an indicator to assess the degree of obesity and lipid levels…’, but referring to them in the introduction section reflects insight within this field.

This is difficult, but consider re-writing the Conclusion so that it captures the contribution of this study to the body of scientific knowledge more distinctly.

Thank you for choosing this journal for your submission. Best wishes for your future research!

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Do you want your identity to be public for this peer review? For information about this choice, including consent withdrawal, please see our Privacy Policy .

Reviewer #1: No

Reviewer #2: No

Reviewer #3: Yes:  Rhena Delport

**********

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Attachment

Submitted filename: PONE-review.docx

pone.0328415.s003.docx (16.4KB, docx)
Attachment

Submitted filename: Comments to Author.docx

pone.0328415.s004.docx (14.1KB, docx)
PLoS One. 2025 Aug 1;20(8):e0328415. doi: 10.1371/journal.pone.0328415.r002

Author response to Decision Letter 1


7 Feb 2025

Dear Editors and Reviewers:

Thank you for your letter and for the reviewers’ comments concerning our manuscript entitled “Non-linear association of cardiometabolic index with gallstone disease in US adults: a cross-sectional study” (ID: 24-47105). Those comments are all valuable and very helpful for revising and improving our paper, as well as the important guiding significance to our research. We have studied the comments carefully and have made a correction. Revised portion are marked in red in the tracked version of manuscript. The final version of our manuscript has been submitted. The main corrections in the paper and the responses to the reviewer’s comments are as flowing:

Responds to the reviewer’s comments:

Reviewer #1:

1.This manuscript states they use logistics regression and restricted cubic spline models but haven’t provided any formulas or parameters deployed in this study. Need to address the rationale of choosing these two models for evaluating CMI – GSD correlation.

Response: We gratefully appreciate your valuable suggestion.We added the rationale of logistics regression and restricted cubic spline models to evaluate the correlation of CMI-GSD in the statistical analysis section of the manuscript.

2.Lipid balance is crucial for gallstone disease, why choose CMI as indicator? Not [TG (mmol/L)/HDL-C (mmol/L)]? How does CMI compares to [TG (mmol/L)/HDL-C (mmol/L)] alone? And how does CMI compares to WHtR alone?

Response: This is a very good suggestion. After synthesizing previous research findings, we posit that compared to individual lipid indices or waist-to-height ratio (WHtR), the cardiometabolic index (CMI) may provide a more comprehensive reflection of human metabolic status. It is noteworthy that we will conduct comparative analyses of these parameters in subsequent multicenter randomized controlled clinical trials to more directly demonstrate the advantages of the CMI index.

3.Lack visuals for logistics regression results and subgroup analysis.

Response: Thanks for your reminder. We have put the forest diagram into Figures 2 and 3.

4.Processed data (2825 out of 15,560) is not provided.

Response: We have uploaded the filtered data to https://figshare.com, DOI: 10.6084/m9.figshare.28323725.

5.Although adjustments for multiple covariates were made, some potential confounders like diet habits, physical activity, and genetic predisposition are not accounted for. Discussing their potential impact on the results would improve the study's robustness.

Response: We think this is an excellent suggestion.We have included physical activity in the covariate and adjusted it to improve the robustness of the results. However, due to the limitations of the NHANES database, diet habits and genetic predisposition are not currently available in the database.

6.Expand bias discussion (lack of other important factors as above). Address limitations of self-reported data -- could introduce recall bias. Highlight this as a limitation and consider suggesting longitudinal studies for validation.

Response: Thank you for the good advice. We have supplemented and highlighted the limitations of this study in the last paragraph of the discussion.

7.Provide more insights on the subgroup analysis in the results, particularly regarding gender differences. Emphasize the clinical implications of gender-based variations in CMI's impact on GSD.

Response: Thank you for your comments. We have added on lines 3 to 7 of page 10.

8.While the study indicates that CMI could be a screening tool, it may be helpful to discuss how CMI could complement existing GSD screening practices. Elaborate on how clinicians might integrate CMI in routine evaluations.

Response: We think this is an excellent suggestion. We have already added lines 250 to 255 in this manuscript.

9.table 1: need to clearly indicate readers they are “logistic regression” models. The 4th “Q3” should be Q4.

Response: Thank you for the good advice. We have supplemented the title in Table 1 and corrected "Q3" to "Q4" in Table 2.

10.figure 2 is too rough. It shows “figure 1” at the top left corner. Need more comprehensive captions explaining all elements including in the plot like the shade and cross-point. Enlarge x-axis and y-axis font size.

Response: Thank the reviewer for reading our paper carefully and giving the above positive comments. We have reworked Figure 4 and supplemented it in the first paragraph on page 8.

Reviewer #2

1.What influence does the use of NHANES data, which is cross-sectional in nature, have on how we interpret the relationship between CMI and gallstone disease (GSD)?

Response: This is a very good suggestion. We must admit that there are some inherent limitations to this study. Because this study is a cross-sectional study based on NHANES data, a causal relationship between CMI and GSD cannot be determined. However, in the follow-up study, our team will conduct a multicenter randomized controlled clinical trial to verify the relationship between the two.

2.Would incorporating other biomarkers or cardiometabolic indicators (for example, HOMA-IR or LDL cholesterol levels) into the CMI calculation alter its relationship with gallstone disease?

Response: We think this is an excellent suggestion. Some previous studies have found that HOMA-IR and LDL cholesterol levels are closely related to obesity and lipid metabolism, but there are no appropriate calculation methods and studies to incorporate these indicators into CMI calculation. In previous studies, HOMA-IR and LDL cholesterol levels have been found to be significantly associated with the risk of gallstones. Therefore, combined with our study results, we concurred that the inclusion of HOMA-IR and LDL cholesterol levels in CMI calculation would not change their relationship with gallstones, but this needs to be verified by multi-center randomized controlled clinical trials.

3.How does the use of waist-to-height ratio (WHtR) as a component of CMI compare to other measures of central obesity, like waist circumference or waist-to-hip ratio, in terms of both benefits and limitations?

Response: The waist-to-height ratio (WHtR) eliminates potential biases in the assessment of central obesity caused by height by standardizing waist circumference relative to height. Compared to waist circumference (WC) or waist-to-hip ratio (WHR) alone, WHtR provides a more equitable measure of obesity for populations with significant height variations, such as individuals from different ethnic groups. Studies have shown that WHtR exhibits higher sensitivity and specificity than WC and WHR in predicting the risks of metabolic syndrome, cardiovascular diseases, and diabetes. However, it is important to acknowledge the limitations of WHtR. First, for individuals with extremely tall or short stature, WHtR may underestimate or overestimate obesity risk, necessitating the use of additional indicators (e.g., BMI) for a comprehensive assessment. Second, WC and WHR remain the core metrics recommended by most clinical guidelines, and the clinical application of WHtR has yet to be widely adopted.

4.What is the reliability of using self-reported data from the NHANES questionnaire to diagnose gallstones, and what biases or limitations might arise from relying on self-reported health conditions in epidemiological studies?

Response: Thank you for your comments. In this study, the use of self-reported data from the NHANES questionnaire as the diagnostic criterion for gallstones was based on prior research. However, it is important to acknowledge that reliance on self-reported health conditions in epidemiological studies may introduce biases such as recall bias (e.g., participants may forget or misinterpret diagnostic details) and potential underdiagnosis or misdiagnosis.

5.What are the primary limitations of using a cross-sectional study design to infer causal relationships between CMI and GSD, and how could longitudinal or experimental research designs enhance the validity of these findings?

Response: Thank you for the good advice. First, in a cross-sectional study, both the exposure (CMI) and the outcome (gallstones) are measured simultaneously, making it impossible to determine whether the exposure precedes the outcome. Second, although we controlled for known confounding factors through multivariate adjustments, unmeasured confounders (such as genetic predisposition and dietary patterns) may still influence the results. Lastly, cross-sectional studies only provide a snapshot at a single point in time and cannot reflect the dynamic relationship between cardiometabolic indices and gallstones. In a longitudinal study design, long-term follow-up can help determine whether the exposure precedes the outcome. Additionally, repeated measurements can reveal the dynamic association between metabolic indicators and the risk of gallstones. In experimental study designs, randomized controlled trials, through random allocation, can minimize confounding bias and directly assess the impact of interventions (such as improving metabolic indicators) on gallstone risk. Furthermore, Mendelian randomization can also be used to enhance the reliability of causal inference.

6.While the study demonstrates a significant link between CMI and GSD, what potential biases (such as selection bias, information bias from self-reported diagnoses, or measurement error) should be considered, and what measures could be implemented in future studies to reduce their impact?

Response: We think this is an excellent suggestion. First, this study should consider selection bias: the general community population may not be representative of hospital-based cohorts. Second, information bias: self-reported diagnoses of gallstones may introduce recall bias, particularly since asymptomatic cases are likely to be underreported. Finally, measurement error: errors may arise from the measurement of waist-to-height ratio. In future research, we can track the temporal changes in the development of CMI and gallstones to clarify the temporal sequence and dynamic relationships. Additionally, combining evidence from observational studies, randomized controlled trials, and Mendelian randomization can enhance the robustness of causal inference.

7.The authors propose that CMI could serve as an effective screening tool for identifying individuals at high risk for GSD. How practical is it to implement CMI for this purpose in clinical practice, particularly considering its connection with other metabolic disorders like obesity and diabetes? What limitations might arise, such as issues with cost, accessibility, or applicability across diverse patient populations?

Response: We sincerely thank the editor and all reviewers for their valuable feedback that we have used to improve the quality of our manuscript. We have supplemented the clinical application of CMI in the second paragraph of page 9.

Reviewer #3

1.This research is aligned with other research on cardiometabolic disease and liver disease such as GSD metabolic-associated fatty liver disease (MAFLD), applying different indices and statistical methods to test the association. The biological mechanism and underlying assumptions regarding the associations have been clearly defined previously, and possible co-variates/confounders have been identified, but the questions regarding which CM index is the most sensitive and specific clinical indicator for possible imminent liver disease in different populations residing in different environments and whether a valid universal threshold may be derived from the analyses if the association between the outcome and the index is not linear are not yet been answered. Although this study applied weighting in their analysis and adjusted for all relevant confounders in the multivariate logistic regression analyses, linearity was not observed. Restricted cubic spline analyses were thus performed to test for a ‘dose-dependent’ relationship, but failed to identify a threshold.

Response: Thank you for your comments.We conducted a threshold effect analysis of the relationship between CMI and GSD and included the results in Table 3.

Attachment

Submitted filename: Response.docx

pone.0328415.s006.docx (19.2KB, docx)

Decision Letter 1

Qian Wu

PONE-D-24-47105R1Non-linear association of cardiometabolic index with gallstone disease in US adults: a cross-sectional studyPLOS ONE

Dear Dr. Li,

Thank you for submitting your manuscript to PLOS ONE. After careful consideration, we feel that it has merit but does not fully meet PLOS ONE’s publication criteria as it currently stands. Therefore, we invite you to submit a revised version of the manuscript that addresses the points raised during the review process.

Please make revisions based on the comments of the reviewers.

Please submit your revised manuscript by May 03 2025 11:59PM. If you will need more time than this to complete your revisions, please reply to this message or contact the journal office at plosone@plos.org . When you're ready to submit your revision, log on to https://www.editorialmanager.com/pone/ and select the 'Submissions Needing Revision' folder to locate your manuscript file.

Please include the following items when submitting your revised manuscript:

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If you would like to make changes to your financial disclosure, please include your updated statement in your cover letter. Guidelines for resubmitting your figure files are available below the reviewer comments at the end of this letter.

If applicable, we recommend that you deposit your laboratory protocols in protocols.io to enhance the reproducibility of your results. Protocols.io assigns your protocol its own identifier (DOI) so that it can be cited independently in the future. For instructions see: https://journals.plos.org/plosone/s/submission-guidelines#loc-laboratory-protocols . Additionally, PLOS ONE offers an option for publishing peer-reviewed Lab Protocol articles, which describe protocols hosted on protocols.io. Read more information on sharing protocols at https://plos.org/protocols?utm_medium=editorial-email&utm_source=authorletters&utm_campaign=protocols .

We look forward to receiving your revised manuscript.

Kind regards,

Qian Wu

Academic Editor

PLOS ONE

Journal Requirements:

Please review your reference list to ensure that it is complete and correct. If you have cited papers that have been retracted, please include the rationale for doing so in the manuscript text, or remove these references and replace them with relevant current references. Any changes to the reference list should be mentioned in the rebuttal letter that accompanies your revised manuscript. If you need to cite a retracted article, indicate the article’s retracted status in the References list and also include a citation and full reference for the retraction notice.

[Note: HTML markup is below. Please do not edit.]

Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

1. If the authors have adequately addressed your comments raised in a previous round of review and you feel that this manuscript is now acceptable for publication, you may indicate that here to bypass the “Comments to the Author” section, enter your conflict of interest statement in the “Confidential to Editor” section, and submit your "Accept" recommendation.

Reviewer #1: (No Response)

Reviewer #2: All comments have been addressed

Reviewer #3: (No Response)

**********

2. Is the manuscript technically sound, and do the data support the conclusions?

The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented.

Reviewer #1: Partly

Reviewer #2: Yes

Reviewer #3: No

**********

3. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #1: Yes

Reviewer #2: I Don't Know

Reviewer #3: Yes

**********

4. Have the authors made all data underlying the findings in their manuscript fully available?

The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified.

Reviewer #1: Yes

Reviewer #2: Yes

Reviewer #3: Yes

**********

5. Is the manuscript presented in an intelligible fashion and written in standard English?

PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here.

Reviewer #1: Yes

Reviewer #2: Yes

Reviewer #3: No

**********

6. Review Comments to the Author

Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #1: regarding my previous comment #2, I would compare CMI to the lipid indicator alone to make the choice of CMI technically sound, rather than you "posit" CMI may be a better one. This comparision would be an impoartant evidence to support the comprehensive reflection of CMI. Especially, from the CMI formula, we can see its a combination of the lipid indicator and waist-to-height ratio. They should be most direct comparision that were not supposed to skip.

2.Lipid balance is crucial for gallstone disease, why choose CMI as indicator? Not [TG

(mmol/L)/HDL-C (mmol/L)]? How does CMI compares to [TG (mmol/L)/HDL-C

(mmol/L)] alone? And how does CMI compares to WHtR alone?

"Response: This is a very good suggestion. After synthesizing previous research

findings, we posit that compared to individual lipid indices or waist-to-height ratio

(WHtR), the cardiometabolic index (CMI) may provide a more comprehensive reflection

of human metabolic status. It is noteworthy that we will conduct comparative analyses

of these parameters in subsequent multicenter randomized controlled clinical trials to

more directly demonstrate the advantages of the CMI index."

Reviewer #2: The Author has answered all the comments. They also incorporated the corrections in the manuscript

Reviewer #3: Dear Authors

The following comments have not been addressed in your rebuttal:

General comments

The strength of the manuscript lies in the accommodation of relevant confounders and the application of restricted cubic spline analyses as a novel approach to make sense of the non-linearity of the association between this specific outcome and index.

Consider making more detailed and stronger deductions from the observed results, e.g., the subgroup analyses that were conducted to test for interactions between CMI and specific covariates. What stood out was the preponderance of males rather than females in the highest quartile (62.16 vs 37.8%) and the increasing trend in male proportions across quartiles with a reversed trend in females. This may be highlighted as a novel finding.

Specific comments:

There are numerous syntax errors throughout that need attention.

The Lipid Accumulation Product (LAP) index is mentioned in a sub-title within the Results section. This is the only occurrence of the term. Please clarify its relevance, because the paragraph reports on the CMI and the formulas for the two indices’ calculation differ.

The first paragraph in the introduction addresses Gallstone disease in general. The references are rather outdated. Please consider replacing them or adding more recent references (some of which are included in the above list of references that may be of interest to the authors)

In the third paragraph of this section, the CMI is introduced. You may consider referring to other more recently applied indices and state why you chose the CMI. E.g., that it has better predictive potential, as alluded to in the discussion section You refer to some of these indices in the paragraph within the discussion section that starts with ‘The CMI, as an indicator to assess the degree of obesity and lipid levels…’, but referring to them in the introduction section reflects insight within this field.

Consider re-writing the Conclusion so that it captures the contribution of this study to the body of scientific knowledge more distinctly.

**********

7. PLOS authors have the option to publish the peer review history of their article (what does this mean? ). If published, this will include your full peer review and any attached files.

If you choose “no”, your identity will remain anonymous but your review may still be made public.

Do you want your identity to be public for this peer review? For information about this choice, including consent withdrawal, please see our Privacy Policy .

Reviewer #1: No

Reviewer #2: No

Reviewer #3: No

**********

[NOTE: If reviewer comments were submitted as an attachment file, they will be attached to this email and accessible via the submission site. Please log into your account, locate the manuscript record, and check for the action link "View Attachments". If this link does not appear, there are no attachment files.]

While revising your submission, please upload your figure files to the Preflight Analysis and Conversion Engine (PACE) digital diagnostic tool, https://pacev2.apexcovantage.com/ . PACE helps ensure that figures meet PLOS requirements. To use PACE, you must first register as a user. Registration is free. Then, login and navigate to the UPLOAD tab, where you will find detailed instructions on how to use the tool. If you encounter any issues or have any questions when using PACE, please email PLOS at figures@plos.org . Please note that Supporting Information files do not need this step.

PLoS One. 2025 Aug 1;20(8):e0328415. doi: 10.1371/journal.pone.0328415.r004

Author response to Decision Letter 2


29 Mar 2025

Dear Editors and Reviewers:

Thank you for your letter and for the reviewers’ comments concerning our manuscript entitled “Non-linear association of cardiometabolic index with gallstone disease in US adults: a cross-sectional study” (ID: 24-47105). Those comments are all valuable and very helpful for revising and improving our paper, as well as the important guiding significance to our research. We have studied the comments carefully and have made a correction. Revised portions are marked in red in the tracked version of manuscript. The final version of our manuscript has been submitted. The main corrections in the paper and the responses to the reviewer’s comments are as flowing:

Responds to the reviewer’s comments:

Reviewer #1:

1. Lipid balance is crucial for gallstone disease, why choose CMI as indicator? Not [TG (mmol/L)/HDL-C (mmol/L)]? How does CMI compares to [TG (mmol/L)/HDL-C (mmol/L)] alone? And how does CMI compares to WHtR alone?

Response: We sincerely thank the editor and all reviewers for their valuable feedback that we have used to improve the quality of our manuscript. We used ROC analysis to compare CMI with WHtR and TG/HDL and added this analysis to the article.

Reviewer #3

1. Consider making more detailed and stronger deductions from the observed results, e.g., the subgroup analyses that were conducted to test for interactions between CMI and specific covariates. What stood out was the preponderance of males rather than females in the highest quartile (62.16 vs 37.8%) and the increasing trend in male proportions across quartiles with a reversed trend in females. This may be highlighted as a novel finding.

Response: We sincerely appreciate the insightful observation. We've added this novel finding to the results section.

2. There are numerous syntax errors throughout that need attention. The Lipid Accumulation Product (LAP) index is mentioned in a sub-title within the Results section. This is the only occurrence of the term. Please clarify its relevance, because the paragraph reports on the CMI and the formulas for the two indices’ calculation differ.

Response: Thanks for your reminder. That was a writing error, and we've changed it to CMI.

3. The first paragraph in the introduction addresses Gallstone disease in general. The references are rather outdated. Please consider replacing them or adding more recent references (some of which are included in the above list of references that may be of interest to the authors)

Response: We gratefully appreciate your valuable suggestion. We have added some of the literature from the above list of references to the first paragraph of the introduction.

4. In the third paragraph of this section, the CMI is introduced. You may consider referring to other more recently applied indices and state why you chose the CMI. E.g., that it has better predictive potential, as alluded to in the discussion section You refer to some of these indices in the paragraph within the discussion section that starts with ‘The CMI, as an indicator to assess the degree of obesity and lipid levels…’ but referring to them in the introduction section reflects insight within this field. Consider re-writing the Conclusion so that it captures the contribution of this study to the body of scientific knowledge more distinctly.

Response: Thank the reviewer for reading our paper carefully and giving the above positive comments. We have added these recommendations in the third paragraph of the introduction and rewritten the Conclusion.

Attachment

Submitted filename: Response_auresp_2.docx

pone.0328415.s007.docx (16KB, docx)

Decision Letter 2

Qian Wu

PONE-D-24-47105R2Non-linear association of cardiometabolic index with gallstone disease in US adults: a cross-sectional studyPLOS ONE

Dear Dr. Li,

Thank you for submitting your manuscript to PLOS ONE. After careful consideration, we feel that it has merit but does not fully meet PLOS ONE’s publication criteria as it currently stands. Therefore, we invite you to submit a revised version of the manuscript that addresses the points raised during the review process.

Please make peer-to-peer modifications to the reviewer's comments.

Please submit your revised manuscript by Jun 08 2025 11:59PM. If you will need more time than this to complete your revisions, please reply to this message or contact the journal office at plosone@plos.org . When you're ready to submit your revision, log on to https://www.editorialmanager.com/pone/ and select the 'Submissions Needing Revision' folder to locate your manuscript file.

Please include the following items when submitting your revised manuscript:

  • A rebuttal letter that responds to each point raised by the academic editor and reviewer(s). You should upload this letter as a separate file labeled 'Response to Reviewers'.

  • A marked-up copy of your manuscript that highlights changes made to the original version. You should upload this as a separate file labeled 'Revised Manuscript with Track Changes'.

  • An unmarked version of your revised paper without tracked changes. You should upload this as a separate file labeled 'Manuscript'.

If you would like to make changes to your financial disclosure, please include your updated statement in your cover letter. Guidelines for resubmitting your figure files are available below the reviewer comments at the end of this letter.

If applicable, we recommend that you deposit your laboratory protocols in protocols.io to enhance the reproducibility of your results. Protocols.io assigns your protocol its own identifier (DOI) so that it can be cited independently in the future. For instructions see: https://journals.plos.org/plosone/s/submission-guidelines#loc-laboratory-protocols . Additionally, PLOS ONE offers an option for publishing peer-reviewed Lab Protocol articles, which describe protocols hosted on protocols.io. Read more information on sharing protocols at https://plos.org/protocols?utm_medium=editorial-email&utm_source=authorletters&utm_campaign=protocols .

We look forward to receiving your revised manuscript.

Kind regards,

Qian Wu

Academic Editor

PLOS ONE

Journal Requirements:

Please review your reference list to ensure that it is complete and correct. If you have cited papers that have been retracted, please include the rationale for doing so in the manuscript text, or remove these references and replace them with relevant current references. Any changes to the reference list should be mentioned in the rebuttal letter that accompanies your revised manuscript. If you need to cite a retracted article, indicate the article’s retracted status in the References list and also include a citation and full reference for the retraction notice.

[Note: HTML markup is below. Please do not edit.]

Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

1. If the authors have adequately addressed your comments raised in a previous round of review and you feel that this manuscript is now acceptable for publication, you may indicate that here to bypass the “Comments to the Author” section, enter your conflict of interest statement in the “Confidential to Editor” section, and submit your "Accept" recommendation.

Reviewer #1: All comments have been addressed

Reviewer #3: (No Response)

**********

2. Is the manuscript technically sound, and do the data support the conclusions?

The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented.

Reviewer #1: Yes

Reviewer #3: Yes

**********

3. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #1: Yes

Reviewer #3: Yes

**********

4. Have the authors made all data underlying the findings in their manuscript fully available?

The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified.

Reviewer #1: Yes

Reviewer #3: Yes

**********

5. Is the manuscript presented in an intelligible fashion and written in standard English?

PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here.

Reviewer #1: Yes

Reviewer #3: Yes

**********

6. Review Comments to the Author

Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #1: All my concerns are well addressed. The authors have imporved the study with analysis details along with the critical corrections to the manuscript. I would recommend to publish this manuscript.

Reviewer #3: Thank you for submitting the revised manuscript.

Although all comments have been addressed suitably, there are still a few suggestions for consideration.

Specific comments:

“In contrast (line 98)to previous BRI and LAP indicators, CMI …” Please precede the acronyms with the full terms.

Line 276: Consider replacing ‘literatures’ with ‘reports’.

In Vancouver style, "P-value" should be written with a capital "P" and without a hyphen, as "P value".

General comment:

Line 309: Consider preceding the Conclusion with a summative statement regarding the clinical relevance of these findings, such as:

"However, the clinical relevance of identifying emergent GSD using the CMI is extended by acknowledging the significant relationship between GSD and CVD, probably due to common causal pathways, as established through meta-analysis and meta-regression." [ref. Hasan R, Allahbakhshi F, Shlyk AD, Allahbakhshi K. Gallstones as a predictor of elevated cardiovascular disease risk: A meta-analysis and meta-regression of over 7.4 million participants. PLoS One. 2025 Mar 19;20(3):e0314661. doi: 10.1371/journal.pone.0314661. PMID: 40106516; PMCID: PMC11922230.

Best wishes for your future research!

**********

7. PLOS authors have the option to publish the peer review history of their article (what does this mean? ). If published, this will include your full peer review and any attached files.

If you choose “no”, your identity will remain anonymous but your review may still be made public.

Do you want your identity to be public for this peer review? For information about this choice, including consent withdrawal, please see our Privacy Policy .

Reviewer #1: No

Reviewer #3: No

**********

[NOTE: If reviewer comments were submitted as an attachment file, they will be attached to this email and accessible via the submission site. Please log into your account, locate the manuscript record, and check for the action link "View Attachments". If this link does not appear, there are no attachment files.]

While revising your submission, please upload your figure files to the Preflight Analysis and Conversion Engine (PACE) digital diagnostic tool, https://pacev2.apexcovantage.com/ . PACE helps ensure that figures meet PLOS requirements. To use PACE, you must first register as a user. Registration is free. Then, login and navigate to the UPLOAD tab, where you will find detailed instructions on how to use the tool. If you encounter any issues or have any questions when using PACE, please email PLOS at figures@plos.org . Please note that Supporting Information files do not need this step.

PLoS One. 2025 Aug 1;20(8):e0328415. doi: 10.1371/journal.pone.0328415.r006

Author response to Decision Letter 3


6 Jun 2025

Dear Editors and Reviewers:

Thank you for your letter and for the reviewers’ comments concerning our manuscript entitled “Non-linear association of cardiometabolic index with gallstone disease in US adults: a cross-sectional study” (ID: 24-47105). Those comments are all valuable and very helpful for revising and improving our paper, as well as the important guiding significance to our research. We have studied the comments carefully and have made a correction. Revised portions are marked in red in the tracked version of manuscript. The final version of our manuscript has been submitted. The main corrections in the paper and the responses to the reviewer’s comments are as flowing:

Responds to the reviewer’s comments:

Reviewer #3:

1. “In contrast (line 98) to previous BRI and LAP indicators, CMI …” Please precede the acronyms with the full terms.

Response: We sincerely thank the editor and all reviewers for their valuable feedback that we have used to improve the quality of our manuscript. We have added the full terms before the acronym

2. Line 276: Consider replacing ‘literatures’ with ‘reports’.

Response: Thanks for your reminder. We have made corrections

3. In Vancouver style, "P-value" should be written with a capital "P" and without a hyphen, as "P value".

Response: We sincerely appreciate the insightful observation. We change all the "P-value" in the manuscript to "P-value".

General comment:

4. Line 309: Consider preceding the Conclusion with a summative statement regarding the clinical relevance of these findings, such as: "However, the clinical relevance of identifying emergent GSD using the CMI is extended by acknowledging the significant relationship between GSD and CVD, probably due to common causal pathways, as established through meta-analysis and meta-regression."

Response: Thank the reviewer for reading our paper carefully and giving the above positive comments. We have added these recommendations in line 276.

Attachment

Submitted filename: Response_auresp_3.docx

pone.0328415.s008.docx (15.3KB, docx)

Decision Letter 3

Qian Wu

Non-linear association of cardiometabolic index with gallstone disease in US adults: a cross-sectional study

PONE-D-24-47105R3

Dear Dr. Li,

We’re pleased to inform you that your manuscript has been judged scientifically suitable for publication and will be formally accepted for publication once it meets all outstanding technical requirements.

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Qian Wu

Academic Editor

PLOS ONE

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Reviewers' comments:

Reviewer's Responses to Questions

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Reviewer #3: All comments have been addressed

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Reviewer #3: Yes

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Reviewer #3: Yes

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Reviewer #3: Yes

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Reviewer #3: Yes:  Rhena Delport

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Associated Data

    This section collects any data citations, data availability statements, or supplementary materials included in this article.

    Supplementary Materials

    S1 Table. Association between CMI and gallstone disease (GSD) in NHANES 2017–2020, weighted.

    (DOCX)

    pone.0328415.s001.docx (13.2KB, docx)
    S2 Table. Subgroup analysis between CMI and gallstone disease (GSD).

    (DOCX)

    pone.0328415.s002.docx (13.2KB, docx)
    Attachment

    Submitted filename: PONE-review.docx

    pone.0328415.s003.docx (16.4KB, docx)
    Attachment

    Submitted filename: Comments to Author.docx

    pone.0328415.s004.docx (14.1KB, docx)
    Attachment

    Submitted filename: Response.docx

    pone.0328415.s006.docx (19.2KB, docx)
    Attachment

    Submitted filename: Response_auresp_2.docx

    pone.0328415.s007.docx (16KB, docx)
    Attachment

    Submitted filename: Response_auresp_3.docx

    pone.0328415.s008.docx (15.3KB, docx)

    Data Availability Statement

    All data used for analysis in the study are available from https://figshare.com, DOI: https://10.6084/m9.figshare.28323725.


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