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Gender Differences in the Risk for Incident Non-Alcoholic Fatty Liver Disease According to the Transition of Abdominal Obesity Status: A 16-Year Cohort Study

Nutrients 2023, 15(13), 2880; https://doi.org/10.3390/nu15132880
by Jun-Hyuk Lee 1,2, Soyoung Jeon 3, Hye Sun Lee 3,* and Yu-Jin Kwon 4,*
Reviewer 1: Anonymous
Reviewer 2:
Reviewer 3: Anonymous
Nutrients 2023, 15(13), 2880; https://doi.org/10.3390/nu15132880
Submission received: 28 May 2023 / Revised: 19 June 2023 / Accepted: 22 June 2023 / Published: 25 June 2023
(This article belongs to the Special Issue Diet Quality, Lifestyle and Liver Health)

Round 1

Reviewer 1 Report

 

In this study, the authors report the association between changes of AO pattern and the incidence of  NAFLD using the longitudinal population-based cohort design in Korean men and women.

Please address the following comments

1-Did the authors identify alcohol consumption based on participants filled questionnaires or blood/ urine assessments?

2-can the authors comment on the difference in body fat and smoking status between men and women as it is almost 1.5 times and 6 times less, respectively?

3- Table 2 formatting is required, it is currently hard to draw conclusions about correlations between physical activity and NAFLD incidence

4- is there an interpretation for the difference between men (fig 2B)  and women (fig 3C), persistent >progressed (men) while persistent =progressed (women). Also, by 14 month, the lean men start to develop NAFLD and progressed has high incidence than persistent

5-table3, among all these factor (smoking, physical activity, alcohol drinking, total energy intake. Model 243 3: Model 2 plus smoking, physical activity, alcohol drinking, total energy intake, mean blood pressure, fasting glucose, total cholesterol, hsCRP and ALT) appears to have the highest incidence of NAFLD? IS IT different between men and women?

6- the disturbution of fat differs between men and women where in men it is mainly abdominal while in women it is mainly subcutaneously, how can the authors interpret this in the light of their findings?

7-In the discussion line 279, Previous study results are in line with our findings. Add ref

8- would the authors add the translational impact of this study?

9- please consider grammatical and language check

 

 

Comments for author File: Comments.pdf

can be improved

Author Response

Response to reviewer #1.

In this study, the authors report the association between changes of AO pattern and the incidence of  NAFLD using the longitudinal population-based cohort design in Korean men and women.

 

Please address the following comments

 

1-Did the authors identify alcohol consumption based on participants filled questionnaires or blood/ urine assessments?

Response: Thank you for the question. Information on alcohol consumption was assessed based on the questionnaire. We have included the detailed description on the assessment of alcohol consumption in the revised Materials and Methods section.

2. Materials and Methods

2.2. Data collection

For alcohol consumption, the amount of alcohol intake (g/day) was calculated based on self-reported questionnaire responses using the following equation:

The amount of alcohol intake = the average amount of pure alcohol (10 g/per glass of drink) × the number of glasses of alcoholic drink at a time (glasses/time) × the frequency of alcohol use (times/month) ÷ 30 (days/month).

Heavy drinkers were defined as those with amount of alcohol intake ≥30 g/day for men and ≥20 g/day for women. The rest of the participants were divided into current drinkers or non-drinkers.

 

2-can the authors comment on the difference in body fat and smoking status between men and women as it is almost 1.5 times and 6 times less, respectively?

Response: We appreciate the valuable suggestion from reviewer #1. Upon considering the differences in percentage of body fat and smoking status between men and women, we believe that these factors could provide valuable clues to explain our results. We have now incorporated this point into the revised Discussion section.

4. Discussion

Sex differences were noted in the HR between people who improved AO and those with persistent AO or progression to AO. The HR of men who improved AO was not statistically lower than that of men with persistent AO or progression to AO, while HR of women who improved AO was statistically lower than that of women with persistent AO or progression to AO. For the sex differences in the transition of AO status and the risk for NAFLD, we focus on the differences in sex hormones, percentage of body fat, and smoking status between men and women. Considering a sexual dimorphism in the development of NAFLD [29], estrogen would have a protective role in disease, especially in the absence of AO. However, the protective role of estrogen may be attenuated in the presence of AO in women, which implies that improving AO could be an effective preventive strategy for NAFLD in women. Further research should be performed to confirm the interaction between estrogen and pro-inflammatory cytokines/adipokines from VAT. The different distribution and absolute amount of fat in men and women could also be another explanation for these findings [30]. In this study, we found that women had 1.5 times higher percentage of body fat than men. Women have greater percentage of adipose tissue than men at the same level of BMI; however, women are more likely to store subcutaneous adipose tissue while men are more likely to store VAT for any given amount of fat [31]. In addition, because the cut-off point for defining AO in men is higher than that in women, the absolute amount of VAT could also be higher in men. Compared to women with AO, men with AO may have higher amounts of FFA, pro-inflammatory cytokines, and adipokines released from VAT, which predisposes them to hepatic steatosis through significant hepatic IR and inflammation. Therefore, the impact of the progression to AO would be more significant in men than in women, as men are likely to experience a greater gain in the absolute amount of VAT. Particularly, men had strikingly higher proportion of current smokers, almost six times higher than women. The rapid deposition of fat in the liver occurs after smoking [32]. Long-term smoking can also stimulate glucose oxidative metabolism, leading to the suppression of non-oxidative reactions and resulting in elevated levels of plasma FFA [33]. Therefore, such factors would maintain the risk for developing NAFLD high even if AO improved in men.

 

References

32.      Liu, Y.; Dai, M.; Bi, Y.; Xu, M.; Xu, Y.; Li, M.; Wang, T.; Huang, F.; Xu, B.; Zhang, J.; et al. Active smoking, passive smoking, and risk of nonalcoholic fatty liver disease (NAFLD): a population-based study in China. J Epidemiol 2013, 23, 115-121, doi:10.2188/jea.je20120067.

33.      Zhang, C.X.; Guo, L.K.; Qin, Y.M.; Li, G.Y. Association of polymorphisms of adiponectin gene promoter-11377C/G, glutathione peroxidase-1 gene C594T, and cigarette smoking in nonalcoholic fatty liver disease. J Chin Med Assoc 2016, 79, 195-204, doi:10.1016/j.jcma.2015.09.003.

 

 

 

3- Table 2 formatting is required, it is currently hard to draw conclusions about correlations between physical activity and NAFLD incidence

Response: We apologize for the lack of clarity in presenting Table 2. We have edited Table 2 to improve clarity.

Table 2. Baseline characteristics of men and women according to incident non-alcoholic fatty liver disease.

 

Total

 

 

Men

 

 

Women

 

 

 

No incident

NAFLD

(n=2642)

Incident

NAFLD

(n=1825)

P-value

No incident

NAFLD

(n=1,110)

Incident

NAFLD

(n=757)

P-value

No incident

NAFLD

(n=1,532)

Incident

NAFLD

(n=1,068)

P-value

Age, years

51.4 ± 9.0

51.8 ± 8.4

0.124

52.6 ± 9.1

51.5 ± 8.3

0.010

50.5 ± 8.8

52.0 ± 8.5

<0.001

WC, cm

77.6 ± 7.7

82.5 ± 7.3

<.001

79.0 ± 6.6

83.4 ± 6.0

<.001

76.6 ± 8.2

81.8 ± 8.0

<0.001

Body fat, %

24.9 ± 7.1

27.7 ± 6.9

<.001

19.1 ± 4.8

21.6 ± 5.0

<.001

29.1 ± 5.2

32.0 ± 4.8

<0.001

BMI, kg/m2

23.0 ± 2.6

24.7 ± 2.7

<.001

22.7 ± 2.5

24.2 ± 2.4

<.001

23.2 ± 2.7

25.1 ± 2.8

<0.001

Weight, kg

58.4 ± 8.5

62.6 ± 8.9

<.001

62.8 ± 8.2

67.3 ± 8.3

<.001

55.3 ± 7.3

59.2 ± 7.8

<0.001

Smoking status, n (%)

 

 

0.817

 

 

0.180

 

 

0.231

Non-smoker

1777 (68.0)

1201 (66.8)

 

317 (28.7)

184 (24.4)

 

1460 (96.6)

1017 (97.4)

 

Ex-smoker

332 (12.7)

230 (12.8)

 

322 (29.2)

223 (29.5)

 

10 (0.7)

7 (0.7)

 

Intermittent smoker

46 (1.8)

35 (2.0)

 

39 (3.5)

28 (3.7)

 

7 (0.5)

7 (0.7)

 

Daily smoker

460 (17.6)

333 (18.5)

 

425 (38.5)

320 (42.4)

 

35 (2.3)

13 (1.3)

 

Physical activity, n (%)

 

 

0.778

 

 

0.889

 

 

0.401

Low

186 (7.3)

120 (6.9)

 

58 (5.4)

40 (5.6)

 

128 (8.7)

80 (7.8)

 

Moderate

1544 (60.7)

1057 (60.4)

 

603 (56.4)

414 (57.4)

 

941 (63.8)

643 (62.4)

 

High

815 (32.0)

574 (32.8)

 

408 (38.2)

267 (37.0)

 

407 (27.6)

307 (29.8)

 

Currently drinking, n (%)

1103 (42.1)

804 (44.4)

0.129

698 (63.4)

500 (66.3)

0.197

405 (26.7)

304 (28.8)

0.241

Total energy intake, kcal/day

1927.8 ± 681.0

1943.3 ± 739.6

0.486

1978.9 ± 654.8

2010.1 ± 694.7

0.331

1891.1 ± 697.1

1895.6 ± 766.9

0.880

Mean blood pressure, mmHg

92.1 ± 12.4

95.7 ± 12.2

<.001

94.1 ± 11.8

96.6 ± 11.4

<.001

90.6 ± 12.6

95.1 ± 12.7

<.001

Fasting glucose, mg/dL

80.9 ± 8.4

84.7 ± 15.9

<.001

82.4 ± 9.4

87.0 ± 17.1

<.001

79.9 ± 7.4

83.0 ± 14.8

<.001

Total cholesterol, mg/dL

185.0 ± 32.7

191.2 ± 33.8

<.001

186.7 ± 33.1

192.8 ± 33.5

0.001

183.7 ± 32.3

190.0 ± 34.1

<.001

hsCRP, mg/dL

0.21 ± 0.50

0.25 ± 0.78

0.024

0.23 ± 0.54

0.24 ± 0.49

0.536

0.19 ± 0.46

0.26 ± 0.93

0.025

ALT, IU/L

20.9 ± 8.1

23.3 ± 9.3

<.001

24.1 ± 9.2

27.7 ± 10.4

<.001

18.6 ± 6.4

20.2 ± 6.9

<.001

AST, IU/L

26.1 ± 6.6

26.6 ± 7.1

0.016

27.7 ± 7.0

28.5 ± 7.5

0.018

25.0 ± 6.0

25.3 ± 6.4

0.214

Abbreviations: ALT, alanine aminotransferase; AST, aspartate aminotransferase; BMI, body mass index; hsCRP, high-sensitivity C-reactive protein; WC, waist circumference

 

 

 

 

4- is there an interpretation for the difference between men (fig 2B)  and women (fig 3C), persistent >progressed (men) while persistent =progressed (women). Also, by 14 month, the lean men start to develop NAFLD and progressed has high incidence than persistent

Response: Thank you for the comment. Cumulative incidence rate of NAFLD seems to be higher in progress to AO group than in persistent AO group in men and similar between persistent and progress to AO groups in women. It is plausible that the impact of changes in AO status observed during the two-year exposure period may gradually diminish or become less pronounced over the extended follow-up period of 14 years. Other factors, such as genetic predisposition, lifestyle changes, or medical interventions, may also come into play and potentially mitigate the initial differences between the two groups. We have included this point in the revised Discussion section. The high incidence of the persistent lean group progressing to the AO group in men observed at 14 years may indeed be related to censored data. Kaplan–Meier curves are commonly used in survival analysis, where censored data represents cases where the event (e.g., death or disease occurrence) has not yet happened or the observation is incomplete until the end of the study period. Censored data occurs when the exact survival time is unknown, for example, when the study ends or when a patient is lost to follow-up during the study. Therefore, when there is a sudden increase in the incidence rate at the last observed time point, it may indicate that some of the previously censored cases experienced the event. This increase can occur because of the presence of more censored data at the endpoint.

4. Discussion

Several studies have tried to identify the effect of BMI or WC changes on NAFLD risk. A Korean study found a direct relationship between increasing WC and the incidence of NAFLD and an inverse relationship between decreasing WC and the incidence of NAFLD using the domestic single-center cohort study [21]. The authors defined WC changes as quartiles of the difference in WC between baseline and two-year follow-up (Q1, WC loss group; Q3 and Q4, WC gain group) [21]. Although the study considered the WC changes over time, it did not address the effect of the progression to AO or regression from AO on NAFLD incidence. In the current study, the cumulative incidence rate of NAFLD was similar between persistent AO group and progressed to AO group in both men and women. It is plausible that the impact of changes in AO status observed during the two-year exposure period may gradually diminish or become less pronounced over the extended follow-up period of 14 years. Other factors, such as genetic predisposition, lifestyle changes, or medical interventions, may also come into play and potentially mitigate the initial differences between the two groups. Follow-up studies should be designed to consider various factors to better understand the results.

 

5-table3, among all these factor (smoking, physical activity, alcohol drinking, total energy intake. Model 243 3: Model 2 plus smoking, physical activity, alcohol drinking, total energy intake, mean blood pressure, fasting glucose, total cholesterol, hsCRP and ALT) appears to have the highest incidence of NAFLD? IS IT different between men and women?

Response: Thank you for your comment. Table 3 provides information on various factors, including smoking, physical activity, alcohol drinking, total energy intake, and different models used to assess the incidence of NAFLD. We presented the difference between men and women in the Table 1. Although there was no difference in mean serum hsCRP level between men and women, we adjusted for this variable considering its clinical importance.

Table 1. Baseline characteristics of the study population.

Variables

Total

(n=4,467)

Men

(n=1,867)

Women

(n=2,600)

P-value

Age, years

51.6 ± 8.8

52.1 ± 8.8

51.1 ± 8.7

<0.001

WC, cm

79.6 ± 7.9

80.8 ± 6.7

78.7 ± 8.5

<0.001

Body fat, %

26.0 ± 7.1

20.1 ± 4.9

30.3 ± 5.3

<0.001

BMI, kg/m2

23.7 ± 2.8

23.3 ± 2.6

24.0 ± 2.9

<0.001

Body weight, kg

60.1 ± 8.9

64.6 ± 8.6

56.9 ± 7.7

<0.001

Smoking status, n (%)

 

 

 

<0.001

Non-smoker

2978 (67.5)

501 (27.0)

2477 (96.9)

 

Ex-smoker

562 (12.7)

545 (29.3)

17 (0.7)

 

Intermittent smoker

81 (1.8)

67 (3.6)

14 (0.6)

 

Daily smoker

793 (18.0)

745 (40.1)

48 (1.9)

 

Physical activity, n (%)

 

 

 

<0.001

Low

306 (7.1)

98 (5.5)

208 (8.3)

 

Moderate

2601 (60.5)

1017 (56.8)

1584 (63.2)

 

High

1389 (32.3)

675 (37.7)

714 (28.5)

 

Currently drinking, n (%)

1907 (43.0)

1198 (64.6)

709 (27.5)

<0.001

Total energy intake, kcal/day

1934.1 ± 705.5

1991.6 ± 671.3

1893.0 ± 726.3

<0.001

Mean blood pressure, mmHg

93.6 ± 12.4

95.1 ± 11.7

92.6 ± 12.8

<0.001

Fasting glucose, mg/dL

82.5 ± 12.2

84.3 ± 13.3

81.2 ± 11.2

<0.001

Total cholesterol, mg/dL

187.5 ± 33.3

189.2 ± 33.3

186.3 ± 33.2

0.004

hsCRP, mg/dL

0.23 ± 0.63

0.24 ± 0.52

0.22 ± 0.70

0.437

ALT, IU/L

21.9 ± 8.70

25.6 ± 9.8

19.2 ± 6.6

<0.001

AST, IU/L

26.3 ± 6.8

28.0 ± 7.2

25.2 ± 6.2

<0.001

HOMA-IR

1.320 ± 0.595

1.237 ± 0.567

1.379 ± 0.607

<0.001

HOMA-beta

151.392 ± 136.726

127.824 ± 125.483

168.303 ± 141.886

<0.001

Insulin

6.479 ± 2.772

5.944 ± 2.588

6.864 ± 2.836

<0.001

Abbreviations: ALT, alanine aminotransferase; AST, aspartate aminotransferase; BMI, body mass index; hsCRP, high-sensitivity C-reactive protein; WC, waist circumference; HOMA-IR, homeostatic model assessment for insulin resistance.

 

6- the disturbution of fat differs between men and women where in men it is mainly abdominal while in women it is mainly subcutaneously, how can the authors interpret this in the light of their findings?

Response: We completely agree with reviewer #1's point of view. We believe that the different distribution of body fat can be one of the reasons for the disparate results observed between men and women. We have discussed this point in the Discussion section and provided further interpretation regarding its implications.

4. Discussion

Sex differences were noted in the HR between people who improved AO and those with persistent AO or progression to AO. The HR of men who improved AO was not statistically lower than that of men with persistent AO or progression to AO, while HR of women who improved AO was statistically lower than that of women with persistent AO or progression to AO. For the sex differences in the transition of AO status and the risk for NAFLD, we focus on the differences in sex hormones, percentage of body fat, and smoking status between men and women. Considering a sexual dimorphism in the development of NAFLD [29], estrogen would have a protective role in disease, especially in the absence of AO. However, the protective role of estrogen may be attenuated in the presence of AO in women, which implies that improving AO could be an effective preventive strategy for NAFLD in women. Further research should be performed to confirm the interaction between estrogen and pro-inflammatory cytokines/adipokines from VAT. The different distribution and absolute amount of fat in men and women could also be another explanation for these findings [30]. In this study, we found that women had 1.5 times higher percentage of body fat than men. Women have greater percentage of adipose tissue than men at the same level of BMI; however, women are more likely to store subcutaneous adipose tissue while men are more likely to store VAT for any given amount of fat [31]. In addition, because the cut-off point for defining AO in men is higher than that in women, the absolute amount of VAT could also be higher in men. Compared to women with AO, men with AO may have higher amounts of FFA, pro-inflammatory cytokines, and adipokines released from VAT, which predisposes them to hepatic steatosis through significant hepatic IR and inflammation. Therefore, the impact of the progression to AO would be more significant in men than in women, as men are likely to experience a greater gain in the absolute amount of VAT.

 

7-In the discussion line 279, Previous study results are in line with our findings. Add ref

Response: We have added references for the sentence in the revised Discussion section.

4. Discussion

Previous study results are in line with our findings [22,23].

 

8- would the authors add the translational impact of this study?

Response: Thank you for your comment. We added the following sentence in the conclusion section.

Line 378

In total population, persistent AO and progression to AO are associated with higher risk for NAFLD. Persistent AO was a significant risk factor for developing NAFLD only in women, suggesting that both maintaining lean WC or improvement from AO would be effective strategies for preventing NAFLD in women while maintaining lean WC is more crucial in men. A health strategy that focuses on maintaining a healthy WC throughout life through physical activity and a healthy diet is likely to be more effective in preventing NAFLD than solely relying on reducing WC at a later stage. Also, considering gender-specific risk profiles can ultimately contribute to the development of more effective health policies and strategies for addressing NAFLD and related health concerns. Additional research is warranted to comprehensively assess the severity of NAFLD, in order to obtain a more precise understanding of the relationship between AO and the risk of NAFLD.

 

9- please consider grammatical and language check

Response: Thank you for your comment. The manuscript and submission files, written by authors for whom English is a second language, have been edited by an editor specializing in editing scientific manuscripts.

Author Response File: Author Response.docx

Reviewer 2 Report

This paper is an interesting paper presenting the association between the transition of WC and incident NAFLD. However, I would only call the conclusion ‘preliminary’ due to the following reasons:

1) the validity of disease definition. the NAFLD-liver fat score was developed in a small cross-sectional population with ‘The optimal cut-off point of −0.640 predicted increased liver fat content with a sensitivity of 86% and specificity of 71%’. Whether this score can be used to predict ‘incident’ NAFLD in a Korean population-based cohort is invalid. How accurate is this score to predict incident NAFLD in Korean cohorts? Please find previous scores to support choosing this score. 

2)Another issue is that NAFLD-liver fat score is unable to tell the severity of liver fat or fibrosis deposition in the liver. It is unable to tell whether the incident NAFLD is a mild, moderate or severe fatty liver or NASH. The clinical significance of NAFLD was not as much as incident Diabetes, which was used to calculate the NAFLD-liver fat score. If the authors were unable to find imaging data to define NAFLD, then a proper discussion of limitations and a mild tone in the conclusion should be used.

  1. the authors have excluded more than 2000 participants with previous NAFLD, are they defined by ultrasound or NAFLD-liver fat score? Please specify. The authors has excluded more than half of the total cohort (10,030), sensitivity analysis should be expended.

Minor issues are:

1)Please present the comparison of clinical characteristics among the four groups (Persistent lean, Improved from abdominal obesity, Progressed to abdominal obesity, Persistent abdominal obesity).

  1. please compare HOMA-IR and HOMA-B, fasting glucose, and Insulin in all tables.
  2. current table 3: Please change covariate FPG to HbA1c if it is possible. Try to adjust BMI if possible. 
  3. I did not see Figure 1 in the manuscript. 
  4. The name of the four groups is a bit misleading, persistent lean indicates normal BMI rather than WC.
  5.  

Author Response

Response to reviewer #2.

This paper is an interesting paper presenting the association between the transition of WC and incident NAFLD. However, I would only call the conclusion ‘preliminary’ due to the following reasons:

 

1) the validity of disease definition. the NAFLD-liver fat score was developed in a small cross-sectional population with ‘The optimal cut-off point of −0.640 predicted increased liver fat content with a sensitivity of 86% and specificity of 71%’. Whether this score can be used to predict ‘incident’ NAFLD in a Korean population-based cohort is invalid. How accurate is this score to predict incident NAFLD in Korean cohorts? Please find previous scores to support choosing this score.

Response: We appreciate reviewer #2’s insightful comment. A study conducted in 2014 validated the NAFLD-liver fat score for the Korean population. In the development dataset comprising 15,676 participants, the area under the receiver operating characteristic curve (AUC) of the NAFLD-liver fat score was 0.7782 (sensitivity 37%, specificity 94%, positive predictive value 81%, and negative predictive value 68%). In the external validation dataset, which included a total of 66,868 participants, the AUC of the NAFLD-liver fat score was 0.82 (sensitivity 40%, specificity 94%, positive predictive value 75%, and negative predictive value 79%). We have included this reference in the Materials and Methods section of the revised manuscript. Additionally, we performed a sensitivity analysis, defining NAFLD using the hepatic steatosis index, which was developed and validated in Korea.

2. Materials and Methods

2.4. Diagnosis of NAFLD

We used the NAFLD-liver fat score to diagnose NAFLD [13], a tool that has undergone validation in the Korean population [14].

Reference

14.      Lee, Y.H.; Bang, H.; Park, Y.M.; Bae, J.C.; Lee, B.W.; Kang, E.S.; Cha, B.S.; Lee, H.C.; Balkau, B.; Lee, W.Y.; et al. Non-laboratory-based self-assessment screening score for non-alcoholic fatty liver disease: development, validation and comparison with other scores. PLoS One 2014, 9, e107584, doi:10.1371/journal.pone.0107584.

 

2)Another issue is that NAFLD-liver fat score is unable to tell the severity of liver fat or fibrosis deposition in the liver. It is unable to tell whether the incident NAFLD is a mild, moderate or severe fatty liver or NASH. The clinical significance of NAFLD was not as much as incident Diabetes, which was used to calculate the NAFLD-liver fat score. If the authors were unable to find imaging data to define NAFLD, then a proper discussion of limitations and a mild tone in the conclusion should be used.

Response: Thank you for your valuable comment. You have raised an important issue regarding the limitations of the NAFLD-liver fat score in assessing the severity of liver fat or fibrosis deposition. Unfortunately, imaging data to define NAFLD was not available in the KoGES, we add the limitation and revised the conclusion as follows;

Line 364

Second, we defined NAFLD using a surrogate marker (NAFLD-liver fat score) rather than imaging modalities (abdominal ultrasonography or magnetic resonance image). The NAFLD-liver fat score lacks the ability to differentiate between mild, moderate, or severe fatty liver or NASH in incident NAFLD. Therefore, this study did not assess the severity of liver fat or fibrosis deposition, which limits our understanding of the clinical implications and disease progression within the NAFLD spectrum.

 

Line 378

In total population, persistent AO and progression to AO are associated with higher risk for NAFLD. Persistent AO was a significant risk factor for developing NAFLD only in women, suggesting that both maintaining lean WC or improvement from AO would be effective strategies for preventing NAFLD in women while maintaining lean WC is more crucial in men. A health strategy that focuses on maintaining a healthy WC throughout life through physical activity and a healthy diet is likely to be more effective in preventing NAFLD than solely relying on reducing WC at a later stage. Also, considering gender-specific risk profiles can ultimately contribute to the development of more effective health policies and strategies for addressing NAFLD and related health concerns. Additional research is warranted to comprehensively assess the severity of NAFLD, in order to obtain a more precise understanding of the relationship between AO and the risk of NAFLD.

 

 

 

the authors have excluded more than 2000 participants with previous NAFLD, are they defined by ultrasound or NAFLD-liver fat score? Please specify. The authors has excluded more than half of the total cohort (10,030), sensitivity analysis should be expended.

Response: The participants who were excluded due to previous NAFLD were also identified using the NAFLD-liver fat score. In response to the valuable suggestion from reviewer #2, we conducted a sensitivity analysis for incident metabolic dysfunction-associated fatty liver disease (MAFLD) among 5360 participants. In this analysis, we did not exclude participants with viral hepatitis infection or heavy alcohol consumption, as indicated in Table for reviewers 1. The risk of incident MAFLD remained consistent with the original analysis.

Table for reviewers 1. Association of AO transition status and the risk of incident metabolic dysfunction-associated fatty liver disease among 5360 participants.

 

 

Unadjusted

Model 1

Model 2

Model 3

 

 

HR (95% CI)

p-value

HR (95% CI)

p-value

HR (95% CI)

p-value

HR (95% CI)

p-value

Overall

Persistent lean

ref

 

ref

 

ref

 

ref

 

 

Improved from abdominal obesity

1.409(1.168-1.700)

<.001

1.065(0.878-1.292)

0.520

1.060(0.866-1.297)

0.572

1.058(0.864-1.296)

0.585

 

Progressed to abdominal obesity

2.235(1.963-2.545)

<.001

1.771(1.548-2.024)

<.001

1.790(1.555-2.061)

<.001

1.685(1.461-1.942)

<.001

 

Persistent abdominal obesity

2.698(2.428-2.998)

<.001

1.413(1.232-1.621)

<.001

1.364(1.178-1.578)

<.001

1.226(1.057-1.422)

0.007

Men

Persistent lean

ref

 

ref

 

ref

 

ref

 

 

Improved from abdominal obesity

1.978(1.456-2.688)

<.001

1.218(0.889-1.669)

0.221

1.214(0.882-1.672)

0.234

1.334(0.968-1.838)

0.079

 

Progressed to abdominal obesity

2.168(1.762-2.669)

<.001

1.514(1.222-1.876)

<.001

1.518(1.213-1.900)

<.001

1.411(1.122-1.773)

0.003

 

Persistent abdominal obesity

2.788(2.289-3.397)

<.001

1.150(0.906-1.461)

0.250

1.064(0.829-1.365)

0.625

1.003(0.779-1.291)

0.981

Women

Persistent lean

ref

 

ref

 

ref

 

ref

 

 

Improved from abdominal obesity

1.367(1.075-1.737)

0.011

1.009(0.791-1.288)

0.941

0.989(0.763-1.282)

0.935

0.949(0.730-1.232)

0.692

 

Progressed to abdominal obesity

2.479(2.092-2.936)

<.001

1.927(1.619-2.293)

<.001

1.939(1.613-2.331)

<.001

1.861(1.547-2.240)

<.001

 

Persistent abdominal obesity

3.018(2.644-3.446)

<.001

1.506(1.268-1.789)

<.001

1.503(1.248-1.810)

<.001

1.367(1.133-1.650)

0.001

Model 1: adjusted for age, sex (in total population), and BMI; model 2: model 1 plus smoking, physical activity, alcohol consumption, total energy intake; model 3: model 2 plus mean blood pressure, glycosylated hemoglobin, total cholesterol, high-sensitivity C-reactive protein, and alanine aminotransferase.

We also conducted an additional sensitivity analysis for incident NAFLD, using a hepatic steatosis index >36, as well as employing another exclusion criterion that conforms to NAFLD among 3858 participants, as shown in Table for reviewers 2. We found that the results were consistent with the original findings.

Table for reviewer 2. Association of AO transition status and the risk of incident NAFLD defined as HSI >36 among 3858 participants.

 

 

Unadjusted

Model 1

Model 2

Model 3

 

 

HR (95% CI)

p-value

HR (95% CI)

p-value

HR (95% CI)

p-value

HR (95% CI)

p-value

Overall

Persistent lean

ref

 

ref

 

ref

 

ref

 

 

Improved from abdominal obesity

1.481(1.198-1.830)

<.001

1.430(1.157-1.768)

0.001

1.452(1.160-1.817)

0.001

1.508(1.201-1.892)

<.001

 

Progressed to abdominal obesity

1.630(1.375-1.932)

<.001

1.558(1.314-1.847)

<.001

1.562(1.307-1.868)

<.001

1.562(1.301-1.876)

<.001

 

Persistent abdominal obesity

2.324(2.032-2.657)

<.001

2.159(1.886-2.472)

<.001

2.119(1.837-2.445)

<.001

2.093(1.802-2.431)

<.001

Men

Persistent lean

ref

 

ref

 

ref

 

ref

 

 

Improved from abdominal obesity

1.749(1.340-2.281)

<.001

1.831(1.403-2.390)

<.001

1.915(1.452-2.525)

<.001

1.948(1.473-2.577)

<.001

 

Progressed to abdominal obesity

1.807(1.463-2.231)

<.001

1.809(1.465-2.234)

<.001

1.815(1.460-2.255)

<.001

1.835(1.471-2.290)

<.001

 

Persistent abdominal obesity

2.652(2.245-3.132)

<.001

2.659(2.251-3.140)

<.001

2.599(2.182-3.097)

<.001

2.548(2.121-3.060)

<.001

Women

Persistent lean

ref

 

ref

 

ref

 

ref

 

 

Improved from abdominal obesity

1.034(0.729-1.467)

0.852

1.033(0.728-1.465)

0.858

1.019(0.693-1.499)

0.925

1.079(0.727-1.602)

0.705

 

Progressed to abdominal obesity

1.328(0.996-1.771)

0.053

1.267(0.947-1.695)

0.112

1.262(0.918-1.735)

0.152

1.298(0.932-1.809)

0.123

 

Persistent abdominal obesity

1.770(1.410-2.223)

<.001

1.645(1.295-2.089)

<.001

1.622(1.253-2.100)

<.001

1.679(1.280-2.201)

<.001

Model 1: adjusted for age, sex (in total population), and BMI; model 2: model 1 plus smoking, physical activity, alcohol consumption, total energy intake; model 3: model 2 plus mean blood pressure, glycosylated hemoglobin, total cholesterol, high-sensitivity C-reactive protein, and alanine aminotransferase.

 

Minor issues are:

 

1)Please present the comparison of clinical characteristics among the four groups (Persistent lean, Improved from abdominal obesity, Progressed to abdominal obesity, Persistent abdominal obesity).

Response: In accordance with reviewer #2’s suggestion, we presented the comparison of clinical characteristics among the four groups in total population, men, and women, respectively, as shown in Table for reviewers 3.

Table for reviewers 3. Clinical characteristics of the study population based the transition status of AO.

1) Overall

 

Characteristics

Total

(n=4467)

Persistent lean WC

(n=3363) (1)

Improved AO

(n=198) (2)

Progressed to AO

(n=376) (3)

Persistent AO

(n=530) (4)

p-value

(1) vs (2)

(1) vs (3)

(1) vs (4)

(2) vs (3)

(2) vs (4)

(3) vs (4)

Overall

Age, years

51.555±8.750

50.652±8.558

51.222±8.742

53.551±8.849

55.996±8.314

<.0001

0.3626

<.0001

<.0001

0.002

<.0001

<.0001

 

Waist circumference, cm

79.596±7.871

76.733±6.098

90.040±3.541

82.626±3.758

91.709±5.048

<.0001

<.0001

<.0001

<.0001

<.0001

0.0005

<.0001

 

Body fat, %

26.039±7.145

24.409±6.716

30.837±5.431

28.417±6.292

32.925±5.322

<.0001

<.0001

<.0001

<.0001

<.0001

0.0001

<.0001

 

BMI, kg/m2

23.707±2.789

22.973±2.402

25.295±2.424

24.701±2.103

27.068±2.702

<.0001

<.0001

<.0001

<.0001

0.0053

<.0001

<.0001

 

Skeletal muscle mass, kg

41.927±7.483

42.050±7.448

41.113±7.208

41.462±7.900

41.782±7.490

0.1805

0.0876

0.1489

0.4442

0.5961

0.2848

0.5274

 

Body weight, kg

60.133±8.934

58.930±8.477

62.894±8.718

61.202±8.319

65.984±9.621

<.0001

<.0001

<.0001

<.0001

0.0256

<.0001

<.0001

 

Smoking status

 

 

 

 

 

<.0001

<.0001

<.0001

<.0001

0.0066

0.0794

0.0035

 

non

2978(67.47)

2099(63.01)

163(84.02)

276(75.41)

440(84.13)

 

 

 

 

 

 

 

 

ex

562(12.73)

484(14.53)

18(9.28)

33(9.02)

27(5.16)

 

 

 

 

 

 

 

 

intermittent

81(1.84)

61(1.83)

4(2.06)

5(1.37)

11(2.10)

 

 

 

 

 

 

 

 

daily

793(17.97)

687(20.62)

9(4.64)

52(14.21)

45(8.60)

 

 

 

 

 

 

 

 

Physical activity

 

 

 

 

 

<.0001

0.0002

<.0001

<.0001

<.0001

<.0001

0.0506

 

low

306(7.12)

219(6.75)

22(11.46)

36(10.20)

29(5.74)

 

 

 

 

 

 

 

 

mod

2601(60.54)

2071(63.80)

137(71.35)

159(45.04)

234(46.34)

 

 

 

 

 

 

 

 

high

1389(32.33)

956(29.45)

33(17.19)

158(44.76)

242(47.92)

 

 

 

 

 

 

 

 

Alcohol consumption

 

 

 

 

 

<.0001

0.0414

0.0032

<.0001

0.9055

0.1299

0.0872

 

No

2524(56.96)

1815(54.36)

120(61.86)

232(62.37)

357(67.87)

 

 

 

 

 

 

 

 

Yes

1907(43.04)

1524(45.64)

74(38.14)

140(37.63)

169(32.13)

 

 

 

 

 

 

 

 

Total energy intake, kcal/day

1934.140±705.464

1926.836±666.265

1879.534±767.781

1994.334±929.209

1957.851±737.737

0.1929

0.3713

0.0818

0.3574

0.0695

0.1937

0.4503

 

Mean blood pressure, mmHg

93.568±12.429

92.532±12.220

92.987±11.914

96.199±13.108

98.488±12.013

<.0001

0.6124

<.0001

<.0001

0.0029

<.0001

0.0056

 

Fasting glucose, mg/dl

82.469±12.171

82.468±12.393

81.566±10.006

81.330±10.053

83.621±12.764

0.0275

0.3105

0.0854

0.0426

0.8252

0.0426

0.0052

 

Total cholesterol, mg/dl

187.504±33.256

186.517±33.014

189.470±35.448

186.790±33.830

193.536±32.957

<.0001

0.2239

0.88

<.0001

0.3578

0.1414

0.0026

 

hsCRP

0.226±0.629

0.210±0.489

0.199±0.256

0.281±0.647

0.303±1.220

0.0037

0.8147

0.037

0.0014

0.1371

0.0462

0.5985

 

ALT

21.889±8.698

22.200±9.123

21.384±7.706

21.402±7.915

20.445±6.339

0.0001

0.1985

0.0908

<.0001

0.9814

0.1943

0.1023

 

AST

26.343±6.774

26.577±7.022

25.424±4.767

25.926±6.331

25.494±5.969

0.0006

0.0198

0.0766

0.0006

0.3986

0.901

0.3444

 

HOMA-IR

1.320±0.595

1.294±0.586

1.323±0.587

1.401±0.579

1.421±0.646

<.001

0.5111

0.001

<.001

0.1359

0.0463

0.6028

 

HOMA-beta

151.392±136.726

150.020±142.570

160.054±113.915

162.690±113.323

148.877±120.578

0.2761

0.3168

0.0888

0.8581

0.8266

0.3274

0.1345

 

Insulin

6.479±2.772

6.351±2.723

6.603±2.876

6.975±2.787

6.894±2.948

<.001

0.2132

<.001

<.001

0.1253

0.2068

0.6622

2) Men

 

Characteristics

Total

(n=1867)

Persistent lean WC

(n=1607) (1)

Improved AO

(n=50) (2)

Progressed to AO

(n=115) (3)

Persistent AO

(n=95) (4)

p-value

(1) vs (2)

(1) vs (3)

(1) vs (4)

(2) vs (3)

(2) vs (4)

(3) vs (4)

Men

Age, years

52.147±8.779

51.866±8.767

53.400±8.519

54.070±8.946

53.916±8.495

0.0072

0.2228

0.0092

0.0268

0.6518

0.7361

0.8992

 

Waist circumference, cm

80.800±6.739

79.303±5.757

91.960±2.241

85.997±2.801

93.971±3.222

<.0001

<.0001

<.0001

<.0001

<.0001

0.0349

<.0001

 

Body fat, %

20.130±4.880

19.503±4.583

24.896±4.998

21.874±4.597

26.179±4.008

<.0001

<.0001

<.0001

<.0001

0.0001

0.1112

<.0001

 

BMI, kg/m2

23.331±2.571

22.878±2.326

25.927±2.123

25.018±1.739

27.602±1.956

<.0001

<.0001

<.0001

<.0001

0.0191

<.0001

<.0001

 

Skeletal muscle mass, kg

48.589±5.824

47.973±5.634

51.235±5.352

51.391±4.936

54.253±5.865

<.0001

<.0001

<.0001

<.0001

0.8698

0.0022

0.0002

 

Body weight, kg

64.613±8.574

63.250±7.927

72.267±6.540

69.657±5.770

77.624±7.639

<.0001

<.0001

<.0001

<.0001

0.0489

<.0001

<.0001

 

Smoking status

 

 

 

 

 

0.0032

0.0011

0.8051

0.0384

0.0026

0.0171

0.4516

 

non

501(26.96)

424(26.50)

22(44.00)

27(23.89)

28(29.47)

 

 

 

 

 

 

 

 

ex

545(29.33)

472(29.50)

18(36.00)

32(28.32)

23(24.21)

 

 

 

 

 

 

 

 

intermittent

67(3.61)

51(3.19)

3(6.00)

5(4.42)

8(8.42)

 

 

 

 

 

 

 

 

daily

745(40.10)

653(40.81)

7(14.00)

49(43.36)

36(37.89)

 

 

 

 

 

 

 

 

Physical activity

 

 

 

 

 

<.0001

0.0157

<.0001

0.0045

<.0001

<.0001

0.1494

 

low

98(5.47)

82(5.31)

3(6.12)

10(9.52)

3(3.26)

 

 

 

 

 

 

 

 

mod

1017(56.82)

902(58.42)

38(77.55)

37(35.24)

40(43.48)

 

 

 

 

 

 

 

 

high

675(37.71)

560(36.27)

8(16.33)

58(55.24)

49(53.26)

 

 

 

 

 

 

 

 

Alcohol consumption

 

 

 

 

 

0.4018

0.1706

0.8994

0.3357

0.2829

0.0875

0.4068

 

No

657(35.42)

565(35.38)

22(44.90)

41(35.96)

29(30.53)

 

 

 

 

 

 

 

 

Yes

1198(64.58)

1032(64.62)

27(55.10)

73(64.04)

66(69.47)

 

 

 

 

 

 

 

 

Total energy intake, kcal/day

1991.574±671.299

1977.268±646.092

1973.773±669.903

2098.156±923.697

2114.745±714.901

0.0846

0.9714

0.0656

0.0575

0.279

0.2356

0.8609

 

Mean blood pressure, mmHg

95.117±11.716

94.713±11.652

96.573±10.399

96.655±12.855

99.319±11.114

0.0007

0.2672

0.085

0.0002

0.967

0.1783

0.0999

 

Fasting glucose, mg/dl

84.253±13.259

84.268±13.575

85.900±13.796

82.270±10.485

85.537±10.025

0.237

0.3912

0.1185

0.3645

0.1061

0.8754

0.0756

 

Total cholesterol, mg/dl

189.197±33.332

189.073±33.291

200.360±33.559

184.043±35.212

191.663±30.399

0.0305

0.0183

0.1176

0.4611

0.0038

0.1349

0.0988

 

hsCRP

0.235±0.520

0.226±0.488

0.255±0.317

0.342±0.970

0.236±0.317

0.1484

0.7012

0.0218

0.8663

0.3259

0.8308

0.1417

 

ALT

25.567±9.843

25.515±9.997

26.000±8.074

26.609±9.710

24.947±8.101

0.614

0.7318

0.2501

0.585

0.7152

0.5407

0.2238

 

AST

27.988±7.242

28.049±7.360

26.640±5.236

28.174±6.596

27.442±6.871

0.4824

0.1756

0.8584

0.4274

0.2114

0.5263

0.4662

 

HOMA-IR

1.237±0.567

1.228±0.560

1.272±0.606

1.336±0.529

1.250±0.701

0.2459

0.594

0.0485

0.7109

0.5009

0.8304

0.2748

 

HOMA-beta

127.824±125.483

128.427±130.460

111.803±71.955

149.653±94.665

99.692±80.746

0.0284

0.3603

0.0806

0.03

0.0771

0.5826

0.0041

 

Insulin

5.944±2.588

5.895±2.536

5.990±2.756

6.618±2.661

5.936±3.154

0.0384

0.7983

0.0038

0.8816

0.1515

0.9045

0.057

3) Women

 

Characteristics

Total

(n=2600)

Persistent lean WC

(n=1756) (1)

Improved AO

(n=148) (2)

Progressed to AO

(n=261) (3)

Persistent AO

(n=435) (4)

p-value

(1) vs (2)

(1) vs (3)

(1) vs (4)

(2) vs (3)

(2) vs (4)

(3) vs (4)

Women

Age, years

51.130±8.706

49.541±8.210

50.486±8.721

53.322±8.813

56.451±8.214

<.0001

0.1835

<.0001

<.0001

0.0009

<.0001

<.0001

 

Waist circumference, cm

78.731±8.488

74.382±5.416

89.391±3.668

81.141±3.113

91.216±5.239

<.0001

<.0001

<.0001

<.0001

<.0001

0.0002

<.0001

 

Body fat, %

30.275±5.253

28.891±5.004

32.804±3.939

31.310±4.523

34.393±4.352

<.0001

<.0001

<.0001

<.0001

0.0025

0.0005

<.0001

 

BMI, kg/m2

23.977±2.906

23.060±2.467

25.086±2.487

24.562±2.234

26.951±2.828

<.0001

<.0001

<.0001

<.0001

0.0426

<.0001

<.0001

 

Skeletal muscle mass, kg

37.152±4.149

36.639±3.977

37.762±3.804

37.070±4.032

39.068±4.428

<.0001

0.0012

0.1095

<.0001

0.0974

0.0007

<.0001

 

Body weight, kg

56.918±7.721

54.976±6.888

59.791±6.956

57.476±6.297

63.442±8.003

<.0001

<.0001

<.0001

<.0001

0.0014

<.0001

<.0001

 

Smoking status

 

 

 

 

 

0.8766

0.8122

0.7277

0.8421

0.7401

0.8378

0.4748

 

non

2477(96.91)

1675(96.76)

141(97.92)

249(98.42)

412(96.26)

 

 

 

 

 

 

 

 

ex

17(0.67)

12(0.69)

0(0.00)

1(0.40)

4(0.93)

 

 

 

 

 

 

 

 

intermittent

14(0.55)

10(0.58)

1(0.69)

0(0.00)

3(0.70)

 

 

 

 

 

 

 

 

daily

48(1.88)

34(1.96)

2(1.39)

3(1.19)

9(2.10)

 

 

 

 

 

 

 

 

Physical activity

 

 

 

 

 

<.0001

0.0446

<.0001

<.0001

<.0001

<.0001

0.08

 

low

208(8.30)

137(8.05)

19(13.29)

26(10.48)

26(6.30)

 

 

 

 

 

 

 

 

mod

1584(63.21)

1169(68.68)

99(69.23)

122(49.19)

194(46.97)

 

 

 

 

 

 

 

 

high

714(28.49)

396(23.27)

25(17.48)

100(40.32)

193(46.73)

 

 

 

 

 

 

 

 

Alcohol consumption

 

 

 

 

 

0.1483

0.2855

0.4474

0.0701

0.168

0.0433

0.5417

 

No

1867(72.48)

1250(71.76)

98(67.59)

191(74.03)

328(76.10)

 

 

 

 

 

 

 

 

Yes

709(27.52)

492(28.24)

47(32.41)

67(25.97)

103(23.90)

 

 

 

 

 

 

 

 

Total energy intake, kcal/day

1892.960±726.317

1880.997±681.039

1846.313±799.024

1948.911±929.760

1923.448±739.043

0.3494

0.5882

0.163

0.2855

0.1801

0.2786

0.6591

 

Mean blood pressure, mmHg

92.455±12.803

90.536±12.388

91.775±12.178

95.997±13.237

98.307±12.205

<.0001

0.2447

<.0001

<.0001

0.001

<.0001

0.0178

 

Fasting glucose, mg/dl

81.188±11.153

80.821±10.950

80.101±7.886

80.916±9.848

83.202±13.260

0.0005

0.45

0.8975

<.0001

0.4768

0.0034

0.0087

 

Total cholesterol, mg/dl

186.288±33.154

184.179±32.593

185.791±35.420

188.000±33.199

193.945±33.509

<.0001

0.568

0.0808

<.0001

0.515

0.0094

0.0214

 

hsCRP

0.221±0.696

0.195±0.489

0.180±0.229

0.254±0.436

0.318±1.338

0.007

0.8068

0.1956

0.0009

0.2994

0.037

0.2413

 

ALT

19.247±6.613

19.166±6.980

19.824±6.940

19.107±5.634

19.462±5.419

0.5797

0.2452

0.893

0.4038

0.2922

0.565

0.4934

 

AST

25.161±6.153

25.229±6.410

25.014±4.543

24.935±5.959

25.069±5.674

0.8609

0.6819

0.4706

0.6263

0.9012

0.9246

0.7808

 

HOMA-IR

1.379±0.607

1.355±0.604

1.340±0.582

1.429±0.598

1.459±0.628

0.0055

0.7764

0.066

0.0014

0.1552

0.04

0.5297

 

HOMA-beta

168.303±141.886

169.780±150.153

176.029±120.742

168.384±120.296

159.643±125.166

0.5232

0.607

0.8821

0.1828

0.6006

0.2252

0.4317

 

Insulin

6.864±2.836

6.769±2.821

6.810±2.896

7.132±2.832

7.103±2.863

0.059

0.8654

0.0534

0.0279

0.2694

0.2779

0.8945

 

 

 

please compare HOMA-IR and HOMA-B, fasting glucose, and Insulin in all tables.

Response: As fasting glucose was already shown in Table 1 and Table 2, we added the results for the comparison of HOMA-IR and HOMA-B, and Insulin in the revised Table 1 and Table 2.

Table 1. Baseline characteristics of the study population.

Variables

Total

(n=4,467)

Men

(n=1,867)

Women

(n=2,600)

P-value

Fasting glucose, mg/dL

82.5 ± 12.2

84.3 ± 13.3

81.2 ± 11.2

<0.001

HOMA-IR

1.320 ± 0.595

1.237 ± 0.567

1.379 ± 0.607

<0.001

HOMA-beta

151.392 ± 136.726

127.824 ± 125.483

168.303 ± 141.886

<0.001

Insulin

6.479 ± 2.772

5.944 ± 2.588

6.864 ± 2.836

<0.001

Abbreviations: ALT, alanine aminotransferase; AST, aspartate aminotransferase; BMI, body mass index; hsCRP, high-sensitivity C-reactive protein; WC, waist circumference; HOMA-IR, homeostatic model assessment for insulin resistance.

Table 2. Baseline characteristics of men and women according to incident non-alcoholic fatty liver disease.

 

Total

 

 

Men

 

 

Women

 

 

 

No incident

NAFLD

(n=2642)

Incident

NAFLD

(n=1825)

P-value

No incident

NAFLD

(n=1,110)

Incident

NAFLD

(n=757)

P-value

No incident

NAFLD

(n=1,532)

Incident

NAFLD

(n=1,068)

P-value

Fasting glucose, mg/dL

80.9 ± 8.4

84.7 ± 15.9

<.001

82.4 ± 9.4

87.0 ± 17.1

<.001

79.9 ± 7.4

83.0 ± 14.8

<.001

HOMA-IR

1.261 ± 0.561

1.405 ± 0.631

<0.001

1.177 ± 0.533

1.326 ± 0.603

<0.001

1.321 ± 0.572

1.462 ± 0.645

<.0001

HOMA-beta

155.186 ± 137.717

145.890 ± 135.126

0.026

133.450 ± 144.596

119.553 ± 89.774

0.011

170.934 ± 130.311

164.525 ± 157.008

0.273

Insulin

6.288 ± 2.677

6.757 ± 2.883

<0.001

5.759 ± 2.496

6.217 ± 2.697

<0.001

6.671 ± 2.738

7.140 ± 2.949

<.0001

Abbreviations: ALT, alanine aminotransferase; AST, aspartate aminotransferase; BMI, body mass index; hsCRP, high-sensitivity C-reactive protein; WC, waist circumference; HOMA-IR, homeostatic model assessment for insulin resistance.

 

current table 3: Please change covariate FPG to HbA1c if it is possible. Try to adjust BMI if possible.

Response: In accordance with reviewer #2’s suggestion, we changed covariate FPG to HbA1c and adjusted BMI as a covariate in the revised Table 3 as below:

Table 3. Cox proportional hazards regression analysis for incident non-alcoholic fatty liver disease according to abdominal obesity patterns.

 

 

Unadjusted

Model 1

Model 2

Model 3

 

 

HR (95% CI)

p-value

HR (95% CI)

p-value

HR (95% CI)

p-value

HR (95% CI)

p-value

Total

Persistent lean WC

ref

 

ref

 

ref

 

ref

 

 

Improved from abdominal obesity

1.39 (1.13–1.72)

0.002

1.03 (0.83–1.27)

0.822

1.02 (0.81–1.28)

0.852

1.06 (0.84–1.33)

0.637

 

Progressed to abdominal obesity

2.26 (1.97–2.61)

<.001

1.73 (1.52–2.03)

<.001

1.77 (1.52–2.06)

<.001

1.73 (1.48–2.02)

<.001

 

Persistent abdominal obesity

2.56 (2.26–2.89)

<.001

1.32 (1.13–1.54)

<.001

1.29 (1.09–1.52)

0.003

1.33 (1.13–1.57)

<.001

Men

Persistent lean WC

ref

 

ref

 

ref

 

ref

 

 

Improved from abdominal obesity

1.91 (1.32–2.77)

0.001

1.30 (0.89–1.90)

0.180

1.34 (0.90–1.98)

0.146

1.47 (0.99–2.18)

0.055

 

Progressed to abdominal obesity

2.25 (1.77–2.86)

<.001

1.60 (1.25–2.05)

<.001

1.57 (1.21–2.05)

<.001

1.60 (1.22–2.09)

<.001

 

Persistent abdominal obesity

2.78 (2.14–3.61)

<.001

1.20 (0.88–1.64)

0.249

1.12 (0.81–1.54)

0.505

1.21 (0.87–1.69)

0.253

Women

Persistent lean WC

ref

 

ref

 

ref

 

ref

 

 

Improved from abdominal obesity

1.33 (1.03–1.73)

0.029

0.95 (0.73–1. 23)

0.691

0.93 (0.70–1.23)

0.586

0.93 (0.71–1.24)

0.628

 

Progressed to abdominal obesity

2.38 (2.00–2.84)

<.001

1.81 (1.51–2.17)

<.001

1.83 (1.51–2.21)

<.001

1.78 (1.47–2.16)

<.001

 

Persistent abdominal obesity

2.70 (2.33–3.12)

<.001

1.31 (1.09–1.58)

0.004

1.31 (1.07–1.59)

0.008

1.36 (1.12–1.65)

0.002

Model 1: adjusted for age, sex (in total population), and body mass index; model 2: model 1 plus smoking, physical activity, alcohol consumption, total energy intake; model 3: model 2 plus mean blood pressure, glycosylated hemoglobin, total cholesterol, high-sensitivity C-reactive protein, and alanine aminotransferase.

 

2. Materials and Methods

2.5. Statistical analysis

In model 1, we adjusted for sex, age, and BMI. In model 2, we adjusted for variables used in model 1 plus smoking status, alcohol consumption status, physical activity, and total energy intake. In model 3, we adjusted for variables used in model 2 plus MBP, HbA1c, serum total cholesterol, CRP, and ALT levels.

 

3. Results

Table 3 presents the HR (95% CI) for NAFLD incidence according to the longitudinal AO patterns using Cox proportional hazards regression model. Compared with the reference persistent lean WC group, the HRs (95% CI) for NAFLD incidence in improved AO, progressed to AO, and persistent AO groups were 1.39 (1.13–1.72), 2.26 (1.97–2.61), and 2.56 (2.26–2.89), respectively. In model 3, compared to persistent lean WC group, the fully adjusted HRs (95% CI) for NAFLD incidence in improved AO, progressed to AO, and persistent AO groups were 1.06 (0.84–1.33), 1.73 (1.48–2.02), and 1.33 (1.13–1.57), respectively. In pairwise comparison analysis, both progressed to AO and persistent AO groups had significantly higher risk for developing NAFLD than improved AO group. There was no difference in the risk for developing NAFLD between progressed to AO and persistent AO groups (Supplementary Table 2). In men, compared to the reference persistent lean WC group, the HRs (95% CI) for NAFLD incidence in improved AO, progressed to AO, and persistent AO groups were 1.91 (1.32–2.77), 2.25 (1.77–2.86), and 2.78 (2.14–3.61), respectively. In progress to AO group, these significant associations were consistently noticed in models 1, 2, and 3. In pairwise comparison analysis, progressed to AO group had a significantly higher risk for developing NAFLD than persistent lean WC group. There was no difference in the risk for developing NAFLD between progressed to AO and persistent AO groups and between improved AO and persistent AO groups (Supplementary Table 2).In women, compared to the reference persistent lean WC group, the HRs (95% CI) for NAFLD incidence in improved AO, progressed to AO, and persistent AO groups were 1.33 (1.03–1.73), 2.38 (2.00–2.84), and 2.70 (2.33–3.12), respectively. In progress to AO and persistent AO groups, these associations remained statistically significant in adjusted models. In pairwise comparison analysis, women showed similar patterns of association as those in the total population (Supplementary Table 2).

 

4. Discussion

In this study, we found that participants who had persistent AO, progressed to AO, or improved AO had significantly higher risk for NAFLD incidence compared to persistently lean WC participants. Men who had progressed to AO over two years had significantly higher risk for NAFLD than those without any AO. Women who had persistent AO or progressed to AO had significantly higher risk for NAFLD than those who had no AO or improved AO. These associations were noticed even when the observation period was extended for four years.

 

I did not see Figure 1 in the manuscript.

Response: We really apologize the omitting figure 1. We added the Figure 1.

Figure 1. Flow chart of the study population.

 

The name of the four groups is a bit misleading, persistent lean indicates normal BMI rather than WC.

Response: Thank you for your valuable comment. We have revised ‘lean’ to ‘lean WC’ throughout the manuscript.

 

Author Response File: Author Response.docx

Reviewer 3 Report

The manuscript is well written. All sections appropriately provide detailed information, except conclusion (see further comments). Methods and results are well described, tehnical editing is required (explained in further comments). Researchers provided an interesting insight into correlation of NAFLD and abdominal obesity.

In abstract (an throught the study) consider a better term for a "improved from AO", perhaps just "improved AO"

LINE 42 Decode this as interleukin 6 (IL-6) and tumor necrosis factor α (TNF-α).

LINE 43 aggravation of insulin resistance - not a correct term, worsening, increase, progression instead aggravation should be used.

LINE 45 Untangle this sentance/divide in two: Free fatty acids released from adipocytes flow through blood to the liver and contribute to hepatic steatosis by inducing de novo lipogenesis resulted from decreased mitochondrial β-oxidation of fat and increasing the synthesis of triglycerides.

LINE 53 - define which AO patterns in the introduction

LINE 55 However, the relationship between AO patterns and the incidence of NAFLD has not been verified. - This is simply not true, I believe you overgeneralized in this sentance. Specifiy what exactly is "not verified", or not understood enough. There is plenty evidence investigatin correlation of NAFLD and different AO "patterns" in differently designed studies. Reformulate the sentance - simply as you explained at the end of the discussion (LINE 331).

Line 122-124 - separate this formula as a figure or as an equation (available instructions in mdpi instructions for authors). 

LINE 148 - would suggest a better term for improved from AO - to just improved AO or another term.

LINE 157 - as previously mentioned, use mdpi equation implementation instructions to separate the equations, throught the manuscript for a better organization of the paper.

Tables 1 and 2 should be organized better, the right column is really confusing, perhaps separate the rows with borders, as you did in Table 3.

Conclusion - although these results are valuable, and study is overall a contribution to the field, conclusion does not say much. Include precise recommendations, would pharmacotherapy be worth examining, what could be further investigated, perhaps physical activity, pharmacotherapy, etc. among these groups and how it would affect the results and contribute to ameliorating NAFLD.

Well written, minor editing required.

Author Response

Response to Reviewer #3

The manuscript is well written. All sections appropriately provide detailed information, except conclusion (see further comments). Methods and results are well described, tehnical editing is required (explained in further comments). Researchers provided an interesting insight into correlation of NAFLD and abdominal obesity.

 

In abstract (an throught the study) consider a better term for a "improved from AO", perhaps just "improved AO"

Response: Thank you for your valuable comment. We have revised "improved from AO" to "improved AO" throughout the manuscript.

 

LINE 42 Decode this as interleukin 6 (IL-6) and tumor necrosis factor α (TNF-α).

Response: Thank you for your valuable comment. We have revised this as recommended.

Excessive visceral adipose tissue (VAT) promotes secretion of pro-inflammatory cytokines such as interleukin 6 (IL-6) and tumor necrosis factor α (TNF-α), which leads to the development and worsening of insulin resistance [4].

 

LINE 43 aggravation of insulin resistance - not a correct term, worsening, increase, progression instead aggravation should be used.

Response: Thank you for your valuable comment. We have modified this as recommended.

Excessive visceral adipose tissue (VAT) promotes secretion of pro-inflammatory cytokines such as interleukin 6 (IL-6) and tumor necrosis factor α (TNF-α), which leads to the development and worsening of insulin resistance [4].

 

LINE 45 Untangle this sentance/divide in two: Free fatty acids released from adipocytes flow through blood to the liver and contribute to hepatic steatosis by inducing de novo lipogenesis resulted from decreased mitochondrial β-oxidation of fat and increasing the synthesis of triglycerides.

Response: Thank you for your valuable comment. We have revised this sentence as recommended.

Free fatty acids released from adipocytes flow through the blood to the liver and contribute to hepatic steatosis [6]. This contribution occurs by inducing de novo lipogenesis, resulting from decreased mitochondrial β-oxidation of fat and increasing the synthesis of triglycerides [6].

 

 

LINE 53 - define which AO patterns in the introduction

Response: We apologize for the confusing expression. We have modified as follows:

Since AO status can change over time, it is more important to consider the long-term trends in AO status rather than spot-checked AO status to determine the risk for metabolic diseases.

 

LINE 55 However, the relationship between AO patterns and the incidence of NAFLD has not been verified. - This is simply not true, I believe you overgeneralized in this sentance. Specifiy what exactly is "not verified", or not understood enough. There is plenty evidence investigatin correlation of NAFLD and different AO "patterns" in differently designed studies. Reformulate the sentance - simply as you explained at the end of the discussion (LINE 331).

Response: I apologize for the inaccurate statement. I appreciate your correction. I have rephrased the sentence for clarity as follows:

While there is significant evidence exploring the correlation between different patterns of AO and the incidence of NAFLD in various studies, implications of this relationship may require further investigation and a deeper understanding.

 

Line 122-124 - separate this formula as a figure or as an equation (available instructions in mdpi instructions for authors).

Response: Thank you for your comment. I have separated this formula as an equation.

 

 

LINE 148 - would suggest a better term for improved from AO - to just improved AO or another term.

Response: Thank you for your valuable comment. We have changed this term as recommended.

 

LINE 157 - as previously mentioned, use mdpi equation implementation instructions to separate the equations, throught the manuscript for a better organization of the paper.

Response: Thank you for your comment. I have separated this formula as an equation.

 

DM (Yes: 2, No: 0)

 

Tables 1 and 2 should be organized better, the right column is really confusing, perhaps separate the rows with borders, as you did in Table 3.

Response: We apologize for the confusing expression. We have separated the rows with borders in Table 2 and Table 3.

 

Conclusion - although these results are valuable, and study is overall a contribution to the field, conclusion does not say much. Include precise recommendations, would pharmacotherapy be worth examining, what could be further investigated, perhaps physical activity, pharmacotherapy, etc. among these groups and how it would affect the results and contribute to ameliorating NAFLD.

Response: Thank you for your valuable comment. We revised the conclusion section as follows;

Line 380

In total population, persistent AO and progression to AO are associated with higher risk for NAFLD. Persistent AO was a significant risk factor for developing NAFLD only in women, suggesting that both maintaining lean WC or improvement from AO would be effective strategies for preventing NAFLD in women while maintaining lean WC is more crucial in men. A health strategy that focuses on maintaining a healthy WC throughout life through physical activity and a healthy diet is likely to be more effective in preventing NAFLD than solely relying on reducing WC at a later stage. Also, considering gender-specific risk profiles can ultimately contribute to the development of more effective health policies and strategies for addressing NAFLD and related health concerns. Additional research is warranted to comprehensively assess the severity of NAFLD, in order to obtain a more precise understanding of the relationship between AO and the risk of NAFLD.

 

Author Response File: Author Response.docx

Round 2

Reviewer 2 Report

I agree with the publication.

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