PONE-D-19-32801

Hospital admission with non-alcoholic fatty liver disease is associated with increased all-cause mortality independent of cardiovascular risk factors

PLOS ONE

Dear Dr. Mann,

Thank you for submitting your manuscript to PLOS ONE. I sincerely apologise for the unusually delayed review timeframe for your manuscript. 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.

Your manuscript has been assessed by four reviewers, whose comments are appended below. Although they are all generally quite positive about the study, they raise some concerns about the study timeframe, definition of study populations, and statistical analysis that should be discussed or addressed with the appropriate revisions. In addition, please feel free to use your discretion when deciding whether to include additional references in your revised manuscript.

Please submit your revised manuscript by Sep 11 2020 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: http://journals.plos.org/plosone/s/submission-guidelines#loc-laboratory-protocols

We look forward to receiving your revised manuscript.

Kind regards,

Emily Chenette

Deputy Editor in Chief

PLOS ONE

Journal Requirements:

Additional Editor Comments (if provided):

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

Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

1. 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 #2: Yes

Reviewer #3: Yes

Reviewer #4: Partly

**********

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

Reviewer #1: Yes

Reviewer #2: Yes

Reviewer #3: Yes

Reviewer #4: No

**********

3. 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

Reviewer #4: Yes

**********

4. 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: Yes

Reviewer #4: Yes

**********

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: The research paper PONE-D-19-32801 entitled “Hospital admission with non-alcoholic fatty liver disease is associated with increased all-cause mortality independent of cardiovascular risk factors” has relevance to the scope and the audience of PONE.

This paper aimed to assess the mortality in NAFLD when adjusting for CVD risk factors in a ‘real world’ cohort of inpatients.

The authors suggest that there is a high burden of cardiovascular disease in NAFLD-cirrhosis patients. From a large “real-life” non-specialist registry of hospitalized patients, NAFLD patients have increased overall mortality and rate of liver-related complications compared to controls after adjusting for cardiovascular disease.

Major comments for the authors

1. This analysis was performed on an interesting issue: The effect of NAFLD on overall mortality in a real world setting regardless of other CVD risk factors.

2. It is a well written paper. The text, the figure and the tables are of appropriate extent and content as well as informative.

3. The references are up to date.

4. The results of the paper have practical implications in patients with NAFLD, especially those with cirrhosis.

Reviewer #2: This is an interesting study based on “real world” data.

1] The authors need to be more careful in using abbreviations. For example, “cardiovascular disease” is abbreviated in the Abstract but not used throughout the Abstract. Also, this term is not abbreviated the first time it appears in the Introduction.

The same for NAFLD, HCC etc.

Please check the whole text for similar errors.

2] Was p value 2-sided?

3] Useful refs to comment:

Athyros VG, Tziomalos K, Katsiki N, Doumas M, Karagiannis A, Mikhailidis DP. Cardiovascular risk across the histological spectrum and the clinical manifestations of non-alcoholic fatty liver disease: An update. World J Gastroenterol. 2015;21(22):6820‐6834.

Le MH, Devaki P, Ha NB, et al. Prevalence of non-alcoholic fatty liver disease and risk factors for advanced fibrosis and mortality in the United States. PLoS One. 2017;12(3):e0173499.

4] The median duration of follow-up differed between groups. Does this translate to the severity of the disease in each group? For example, do patients with cirrhosis died earlier? Please comment.

5] Although lifestyle interventions do remain the first-line therapeutic option for NAFLD/NASH, other drugs may be helpful and especially statins and antidiabetic drugs. A brief comment should be added. Useful refs

Athyros VG, Alexandrides TK, Bilianou H, et al. The use of statins alone, or in combination with pioglitazone and other drugs, for the treatment of non-alcoholic fatty liver disease/non-alcoholic steatohepatitis and related cardiovascular risk. An Expert Panel Statement. Metabolism. 2017;71:17‐32.

Stahl EP, Dhindsa DS, Lee SK, Sandesara PB, Chalasani NP, Sperling LS. Nonalcoholic Fatty Liver Disease and the Heart: JACC State-of-the-Art Review. J Am Coll Cardiol. 2019;73(8):948‐963.

6] Drug therapy may affect clinical outcomes. The inability to evaluate drug effects in this study should be mentioned in the limitations.

Katsiki N, Perakakis N, Mantzoros C. Effects of sodium-glucose co-transporter-2 (SGLT2) inhibitors on non-alcoholic fatty liver disease/non-alcoholic steatohepatitis: Ex quo et quo vadimus?. Metabolism. 2019;98:iii‐ix.

Athyros VG, Polyzos SA, Kountouras J, et al. Non-Alcoholic Fatty Liver Disease Treatment in Patients with Type 2 Diabetes Mellitus; New Kids on the Block. Curr Vasc Pharmacol. 2020;18(2):172‐181.

Reviewer #3: This is a retrospective study based on a registry data. I have some comments and suggestions.

Why the inclusion period was only until to 2013 (and not until 2018-2019) and why now do you choose to publish these data?

The diagnosis of this pathology have suffered modification between 2000 and 2013. Therefore, the codification is not sufficiently to be sure that the patients was appropriately included. What where the modalities of diagnosis for these pathologies? I think that this is the main cornerstone of this study (the inhomogeneity of diagnosis for these pathologies).

In table 1, I do not see the statistical significance (p). It would be important. All-cause mortality has the same percentage in controls and NAFL.

In table 2 why do you not put the sixth column for p? It would be easier to follow these data.

``The cirrhosis group showed higher prevalence of heart failure, atrial fibrillation, CKD, and ischaemic heart disease, compared to the NAFL group.`` I suggest to analyze separately this subgroup of patients. It might offers very interestingly data about the relationship between thrombosis risks in patients with cirrhosis.

Reviewer #4: In “Hospital admission with non-alcoholic fatty liver disease is associated with increased all-cause mortality independent of cardiovascular risk factors” Mann and collegues tried to define whether NAFL and NASH are associated with increased all-cause mortality in hospitalised patients. The study was conducted as a retrospective cohort study using ICD-10 coding to define the presence of NAFL, NASH and NAFLD related cirrhosis.

Output of the study were: overall mortality and hepatic outcomes (liver decompensation and HCC). In addition, authors characterized metabolic and cardiovascular comorbidities of NAFLD patients recording specific ICD code, listed in methods section.

Major:

I have some concerns about the populations definition, the statistical methods and the strength of the results.

Populations definition:

1. As authors reported in study limitation section, the use of ICD code to define the presence or the absence of NAFL/NASH, is highly defective. However, some bias could be reduced considering NAFL and NASH as a unique non cirrhotic NAFLD group. Often, asymptomatic NAFLD patients classified as NAFL patients hide NASH patients with normal liver function tests and non-invasive markers of fibrosis.

2. The absence of an ICD10 which refers to NAFLD spectrum does not allow to exclude the presence of nafld among controls (as stated in study limitation section). However, the authors should stress that this bias could underestimated the HR in the analysis and not conversely.

Statistical methods:

3. Since the authors talk about prevalence of liver decompensation/failure or HCC, I suppose that were recorded ad admission in hospital (follow up start time). In statistical methods authors properly say they used Multivariate logistic regression to define factors associated with this outcome. However, they improperly use the “hazard ratio” to define the statistical outcome. In this case, being a no time-corrected method, the statistical outcome is “odds ratio”, please amend properly

4. Figure 1. I think that the Kaplan Mayer curves, being the graphic representation of an univariate model, are not the best graphic model to represent survival in this study. At follow up start time patients and controls had different prevalence of cardiovascular (and liver-related?) conditions that may affect survival. Please consider using multiple survival curve (controls vs NAFLD (as suggested in point 1) and control vs patients with cirrhosis) derived from cox-regression analyses.

5. Why liver decompensation/failure/HCC was not included in cox multivariate regression? The differences in survival may partially been explained by different prevalence of liver complications. An interesting way to test this hypothesis could be an additional cox regression analysis performed after excluding patients whit liver complications

Strength of results:

6. Concern reported in point 5 and the inability to define with certain the cause of hospital admission (follow up start time) raise some doubts that NAFLD patients included in this cohort could represents a cluster of most severe patients in which NAFLD plays a key role.

Minor:

1. Lines 124: another study described the CV burden in patients with NAFLD-cirrhosis, please discuss it (https://doi.org/10.1016/j.atherosclerosis.2017.03.038)

2. Table 1: Adjusted and unadjusted HRs for overall mortality and ORs (?) for Liver failure/decompensation and HCC should be reported in a separate table.

3. The sentence “increased mortality for patients with NAFLD, irrespective of fibrosis” (lines 277-278) is not supported by results. In this study, the only differentiation in the severity of fibrosis could be made comparing cirrhotic with non-cirrhotic patients and, among them there is a wide difference in survival (HR 3.8 vs 2.6 vs. 65.4!)

4. Lines 298-304: a recent study proved higher incidence of CV disease in patients with NAFLD compared to metabolic controls. In addition, in the same study, non-invasive markers of fibrosis identify patients at higher risk for CV events among those with NAFLD. The same study could be discussed in introduction section (lines 101-107) to affirm that fibrosis, in NAFLD patients, is the major predictors of CVE also. doi: 10.1016/j.cgh.2019.12.026

5. Please check through the paper the correct use of NAFLD/NAFL terms. Eg: in figure 1 “NAFLD” was incorrectly used instead of NAFL

**********

6. 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

Reviewer #4: 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.

Hospital admission with non-alcoholic fatty liver disease is associated with increased all-cause mortality independent of cardiovascular risk factors

PONE-D-19-32801R1

Dear Dr. Mann,

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.

Within one week, you’ll receive an e-mail detailing the required amendments. When these have been addressed, you’ll receive a formal acceptance letter and your manuscript will be scheduled for publication.

An invoice for payment will follow shortly after the formal acceptance. To ensure an efficient process, please log into Editorial Manager at http://www.editorialmanager.com/pone/, click the 'Update My Information' link at the top of the page, and double check that your user information is up-to-date. If you have any billing related questions, please contact our Author Billing department directly at authorbilling@plos.org.

If your institution or institutions have a press office, please notify them about your upcoming paper to help maximize its impact. If they’ll be preparing press materials, please inform our press team as soon as possible -- no later than 48 hours after receiving the formal acceptance. Your manuscript will remain under strict press embargo until 2 pm Eastern Time on the date of publication. For more information, please contact onepress@plos.org.

Kind regards,

Michael W Greene, Ph.D.

Academic Editor

PLOS ONE

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 #2: All comments have been addressed

Reviewer #3: All comments have been addressed

**********

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 #2: Yes

Reviewer #3: Yes

**********

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

Reviewer #1: Yes

Reviewer #2: 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 #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: 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: This is a well written paper with results that have clinical implications for the treatment of patients with NAFLD-cirrhosis.

The research paper PONE-D-19-32801 entitled “Hospital admission with non-alcoholic fatty liver disease is associated with increased all-cause mortality independent of cardiovascular risk factors” has relevance to the scope and the audience of PONE.

This paper aimed to assess the mortality in NAFLD when adjusting for CVD risk factors in a ‘real world’ cohort of inpatients.

The authors suggest that there is a high burden of cardiovascular disease in NAFLD-cirrhosis patients. From a large “real-life” non-specialist registry of hospitalized patients, NAFLD patients have increased overall mortality and rate of liver-related complications compared to controls after adjusting for cardiovascular disease.

Major comments for the authors

1. This analysis was performed on an interesting issue: The effect of NAFLD on overall mortality in a real world setting regardless of other CVD risk factors.

2. It is a well written paper. The text, the figure and the tables are of appropriate extent and content as well as informative.

3. The references are up to date.

4. The results of the paper have practical implications in patients with NAFLD, especially those with cirrhosis.

5. Any issues with the paper in the original submission were addressed in a proper way in the revision

Reviewer #2: (No Response)

Reviewer #3: (No Response)

**********

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