PONE-D-20-12241

Self-Assessment of Unilateral and Bimodal Cochlear Implant Experiences in Daily Life

PLOS ONE

Dear Dr. Devocht,

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 consider the comments of the third reviewer who mainly focused on  ​your statistical analysis. He has concerns on the validity of your statistical evaluation, so please do appropriate changes here, at least changes to the text passages and explain why you chose your evaluation approach.

Please submit your revised manuscript by Aug 22 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,

Andreas Buechner, PhD

Academic Editor

PLOS ONE

Journal Requirements:

When submitting your revision, we need you to address these additional requirements.

1. Please ensure that your manuscript meets PLOS ONE's style requirements, including those for file naming. The PLOS ONE style templates can be found at

https://journals.plos.org/plosone/s/file?id=wjVg/PLOSOne_formatting_sample_main_body.pdf and

https://journals.plos.org/plosone/s/file?id=ba62/PLOSOne_formatting_sample_title_authors_affiliations.pdf

2. Thank you for stating the following in the Competing Interests section:

"The authors of this manuscript have read the journal's policy and have the following conflicts: the work of the first author (EMJD) in this investigator-initiated study was financially supported by a research grant from Advanced Bionics Inc. The second author (AMLJ) provided statistical support, made possible by a grant from the Dutch Heinsius-Houbolt foundation. The third author (JC) holds a scientific post in the Advanced Bionics European Research Center. For the remaining authors no conflicts were declared. The study was designed in close cooperation between MUMC+ and Advanced Bionics who also reviewed the final manuscript. Data collection, analysis and decision to publish were all solely accounted for by MUMC+."

We note that one or more of the authors are employed by a commercial company: Advanced Bionics Inc.

2.1. Please provide an amended Funding Statement declaring this commercial affiliation, as well as a statement regarding the Role of Funders in your study. If the funding organization did not play a role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript and only provided financial support in the form of authors' salaries and/or research materials, please review your statements relating to the author contributions, and ensure you have specifically and accurately indicated the role(s) that these authors had in your study. You can update author roles in the Author Contributions section of the online submission form.

Please also include the following statement within your amended Funding Statement.

“The funder provided support in the form of salaries for authors [insert relevant initials], but did not have any additional role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript. The specific roles of these authors are articulated in the ‘author contributions’ section.”

If your commercial affiliation did play a role in your study, please state and explain this role within your updated Funding Statement.

2.2. Please also provide an updated Competing Interests Statement declaring this commercial affiliation along with any other relevant declarations relating to employment, consultancy, patents, products in development, or marketed products, etc. 

Within your Competing Interests Statement, please confirm that this commercial affiliation does not alter your adherence to all PLOS ONE policies on sharing data and materials by including the following statement: "This does not alter our adherence to  PLOS ONE policies on sharing data and materials.” (as detailed online in our guide for authors http://journals.plos.org/plosone/s/competing-interests) . If this adherence statement is not accurate and  there are restrictions on sharing of data and/or materials, please state these. Please note that we cannot proceed with consideration of your article until this information has been declared.

Please include both an updated Funding Statement and Competing Interests Statement in your cover letter. We will change the online submission form on your behalf.

Please know it is PLOS ONE policy for corresponding authors to declare, on behalf of all authors, all potential competing interests for the purposes of transparency. PLOS defines a competing interest as anything that interferes with, or could reasonably be perceived as interfering with, the full and objective presentation, peer review, editorial decision-making, or publication of research or non-research articles submitted to one of the journals. Competing interests can be financial or non-financial, professional, or personal. Competing interests can arise in relationship to an organization or another person. Please follow this link to our website for more details on competing interests: http://journals.plos.org/plosone/s/competing-interests

3. We noted in your Acknowledgement Section that a portion of your manuscript may have been presented or published elsewhere.

 "Preliminary portions of these data were presented at the 9th Asia Pacific

 Symposium on Cochlear Implants and Related Sciences (Nov 2013, Hyderabad, India), the 224th

Annual Meeting of the Dutch Head and Neck Society (April 2014, Nieuwegein, The

Netherlands), the 13th International Conference on Cochlear Implants and Other Implantable

Auditory Technologies (June 2014, Munich, Germany), the 8th international Symposium on

Objective Measures in Auditory Implants (October 2014, Toronto, Canada), the 18th Jarestagung

of the Deutsche Gesellschaft für Audiologie (March 2015, Bochum, Germany) and the Phonak

Conference ‘Hearing loss and audiological technology between present and future’ (June 2016,

Milan, Italy). The contents of this paper were part of the PhD dissertation (July 2019) of the first

author."

Please clarify whether this [conference proceeding or publication] was peer-reviewed and formally published. If this work was previously peer-reviewed and published, in the cover letter please provide the reason that this work does not constitute dual publication and should be included in the current manuscript.

[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: Partly

**********

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

Reviewer #1: Yes

Reviewer #2: Yes

Reviewer #3: 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

**********

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

**********

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 group of bimodal patients surveyed represents one of the largest user groups among CI users and is therefore of fundamental interest. The compilation of the questionnaire seems well thought out and conclusively proven. The questions about spatial hearing are of particular interest. The selection of the static methods appears correct. The formation of subgroups in categories with different residual hearing might have provided further detailed insights into the generally inhomogeneous group of bimodal users. However, a larger number of respondents would also be desirable. Since your survey focuses on Advanced Bionics users, results with newer CI systems in combination with a Naida Link hearing aid would be of interest, since the signal preprocessing of the two systems is very similar and may therefore improve spatial hearing for bimodal users. An indication of this would be desirable as an outlook. The audiometer limit should be specified.

Reviewer #2: I. General

The present paper aims at investigating subjective experiences of unilateral cochlear implant (CI) users by means of questionnaires. Two groups have been explored: BIM, patients who wear a hearing aid (HA) on the contralateral side (n = 26), and UNI, patients who do not (n = 22).

In group BIM contralateral residual hearing is low (96.6 dB, table 1, @250 Hz 82 dB, figure 1). In UNI contralateral residual hearing is even worse (107.6 dB, table 1, @250 Hz 95 dB, figure 1). Between these groups speech comprehension (BIM: 70.4%, UNI: 62.6%) is not statistically significant different (table 1). Both groups show no difference in self-rated disability, hearing handicap or general quality of life. The authors want to find out if their results are in line with other studies [27-30] (line 88-89). They are!

As novelty of this study disability ratings within the group of bimodal users (condition with and without hearing aid) are pointed out (line 89-92). Ratings are better in the HA+CI condition compared to the CI or HA condition alone.

Sounding is good and the topic is discussed deeply, almost lengthily.

II. Specific

Line 60. Among these 11 citations you mentioned many studies with a small number of subjects. But a study with a large number of subjects is missing and should be included: Illg, A., Bojanowicz, M., Lesinski-Schiedat, A., Lenarz, T., & Büchner, A. (2014). Evaluation of the Bimodal Benefit in a Large Cohort of Cochlear Implant Subjects Using a Contralateral Hearing Aid. Otology & Neurotology, 35(9), e240–e244. In this study a statistically significant benefit was found for the bimodal condition in a BIM group of n = 141 subjects. It is interesting that residual hearing was much better comparing to your study group. When your BIM group is wearing CI only, speech comprehension decreases from 70.4% to 58.7%. If they are wearing HA only, still speech recognition scored 46.3%. How can such results be achieved despite of that low residual hearing? Is the group very heterogeneous? Please comment on that.

Line 64-67. These sentences are so similar to [27], p. 513, that it should be marked again as citation. Or e.g. replace “This is not surprising …” by “the authors didn’t find this surprising …”

Line 262-263: Since experience with CI was on average 4 years (table 1), question Q3 is related to a time where residual hearing might have been much better than values given in table 1. You wrote (line 206) that data in table 1 were retrieved „within one year around the time of study involvement“, i.e. at a time where they were already using the CI for about 4 years. You should discuss that and if this might have an impact on conclusions. It would be very interesting to show the amount of residual hearing in the non-implanted ear at the time of CI surgery.

Line 265. You are measuring “quality of hearing” by question Q6, whether the HA was helpful. I think there is a difference between quality and helpfulness and these terms should not be mixed up.

Line 276. According to Q37, you may also include the n=5 who perceived only a little improvement leading to a total of 92% of augmentation of enjoyment in life.

Line 291-293. “Although most (sub)scales did not demonstrate a difference between performance with CI and HA, …” From App2 and Fig 2B I understood that all (sub)scales within the bimodal group did (!) demonstrate a difference between performance with CI (CI was better) and HA, but this difference was significant in only 3 out of 10 (sub)scales (App2). Please comment on that.

Line 361. It would be very comfortable to read the size of your larger sample in parentheses.

Line 364. Please comment a bit more on the term “functional quality”. I think you are referring to question Q6, where you named it helpfulness.

Line 550-552. You wrote that it is “important to comprehend what drives a bimodal user to prefer the bimodal combination in comparison to a unilateral subject” Can you explain more clearly, why it is not simply the amount of residual hearing?

References [18] and [63] are identical; reference [53] is incomplete, but has nearly the same title like [18] and [63].

III. Some typos:

App1_Bimodal Questionaire. First line: ‘ead’ � aid

App1_Bimodal Questionaire. Question 30. ‘enfironment’ � environment

Line 255. „Statistical is defined as a p-value of < 0.05“ � What do you mean? statistical significance?

Line 460. Missing space; andyet � and yet

Reviewer #3: This is a study conducted from data that is "part of a clinical trial". Hence, although following strict CONSORT guidelines may not be needed, still some changes are expected. I list them below, and these needs to be addressed to make the paper statistically viable.

(a) Abstract: The abstract has statements like "...participants report a significant benefit of bimodal activity....", without any statement of the strength of the benefit (say, p-values, etc). This may leave the reader confused, as an example of providing half-baked (summary) information. Same goes when something is non-significant.

(b) Sample size/Power: I am also surprised to see that there is no mention on the sample size/power they are trying to play with, to get the desired effect size. What's the choice behing recruiting 77 subjects? The current study with the sample size employed may very well be regarded as a pilot study; please follow recommendations of proposing, or stating target sample sizes as in the reference below:

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3203750/

(c) Data analysis: Multiple imputation was conducted to fill missing values, which is OK. However, group comparisons directly used parametric two-tailed t-tests. What is the justification? Responses can/may not follow Gaussianity; was that checked? Then, why not available 2-sample nonparametric tests wwere used for a robust comparison.

Furthermore, I am entirely confused why a linear mixed model (LMM) was employed later? It is not clear whether we have subjects having measures for CI, HA and CIHA? LMMs are mostly used under longitudinal designs, with time as an important predictor, and where understanding changes of responses with time is the prime focus. I don't see any time component here (am I wrong?). The writeup needs to be clear on how repetitions are happening for each subject (authors are considering subject as a random effect). If that is the case, simply try a GEE (generalized estimating equation), which is often considered as robust to the choice of the initial covariance structure, although under an asymptotic situation. GEE can be implemented in any standard statistical software. A likelihood-based LMM appeared unnecessary to me here.

The data analysis section should clearly state the reasons why a GEE was done as well, explaining the nature of the clustering in the data, etc.

**********

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

[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.

Self-Assessment of Unilateral and Bimodal Cochlear Implant Experiences in Daily Life

PONE-D-20-12241R1

Dear Dr. Devocht,

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,

Andreas Buechner, PhD

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: (No Response)

**********

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

Reviewer #1: Yes

Reviewer #2: Yes

Reviewer #3: (No Response)

**********

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: (No Response)

**********

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 Response)

**********

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: From my point of view, the author has taken up all the points in question and has sufficiently addressed the proposed changes. The note regarding the audiometer limit meant the maximum sound level that the audiometer can produce. The possible increment was not meant. Basically, that was just a side note that didn't necessarily have to be included.

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