The authors have declared that no competing interests exist.
To identify the differences between persons with schizophrenia (PWS) and general population in France in terms of oral health treatment (tooth scaling, dental treatment and tooth extraction) and the factors associated with these differences.
This retrospective cohort study included PWS identified from a representative sample of 1/97th of the French population (general sample of beneficiaries). PWS were identified from 2014 data by an algorithm that included: F2 diagnostic codes in the register of long-term diseases in 2014 AND
In 2014, 580,219 persons older than 15 years were identified from the 96 metropolitan departments in France; 2,213 were PWS (0.4%). Fewer PWS were found along a diagonal line from north-east to south-west France, and the highest numbers were located in urban departments. PWS were more often male (58.6% vs 48.7%, p<0.001). They were less likely to have had tooth scaling but more likely to have undergone a dental extraction. In one third of departments, more than 50% of PWS had at least one tooth scaling over a three-year period; the rate of dental extraction in these departments ranged from 6 to 23%. Then, a quarter of the departments in which 40 to 100% of PWS had had at least one dental extraction (2/8) presented a rate of tooth scaling ranging from 0 to 28% over the study period.
Compared with the general population, PWS were less likely to have had tooth scaling and dental treatment but more likely to have undergone dental extraction.
Schizophrenia affects between 0.7 and 1% of the worldwide population and 400 000 to 600 000 individuals in France [
The trend towards poor physical health in people with mental illness has been the subject of growing attention [
In the French department of Côte d’Or (530,000 inhabitants), a previous study was conducted with PWS, using a random stratified method. This study showed that, compared with data available for the general population, there were more extractions and missing teeth and fewer dental fillings [
Our aim was to identify the differences between PWS and general population in France in terms of oral health treatment (tooth scaling, dental treatment and tooth extraction) and the factors associated with these differences.
This retrospective cohort study focused on PWS identified from a representative sample of 1/97th of the French population that is known as the EGB (
The EGB was constructed on a national level by the French health insurance agency, which manages the representativeness of the data. It was drawn randomly from a check digit of the beneficiary’s identification number. From a stable, representative sample of the French population, these data allowed us to estimate care pathways and follow-up while excluding the effects of the geographical area, health facility or practices. The EGB was based on the “National System of Health Data” (SNDS) database which collects individual hospital and non-hospital healthcare data. These data include automatically recorded healthcare acts such as biological testing, treatment, medical transport and a register for long-term diseases. Health insurance is compulsory for everyone living in France, and each health act is reimbursed by the French health insurance agency and therefore recorded in SNDS. These data include all types of mandatory health insurance systems (the main national health insurance, health insurance for the agricultural sector, health insurance for the self-employed and 12 other specific health insurance schemes) covering more than 90% of the French population. In 2016, the EGB sample was made up of almost 600,000 health insurance beneficiaries. The reliability of the SNDS has been established in recent studies [
PWS were identified for the year 2014 by an algorithm that included:
Diagnostic Codes F2 in the register of long-term diseases [
The purpose of this algorithm was to identify adult schizophrenia in the SNDS database. It was built using the information obtained from interviews with experts in schizophrenia and based on their procedures to identify in- or out-patients [
The control group was composed of all the people who are included in the EGB and not included in the cohort of patients with schizophrenia.
Because the diagnosis of schizophrenia is rare and difficult before age 15 years [
The main outcomes of interest (in the French Common Classification of Procedures) were; 1) tooth scaling (code HBJD001); 2) dental treatments (codes HBMD0-, HBFD0-); and 3) tooth extraction (code HBGD0-) [
Tooth scaling is a common dental cleaning procedure to remove plaque buildup. Tooth scaling prevents periodontal disease. It is the most common procedure in general dentistry.
Dental treatments were all procedures for filling cavities, root canal treatments, such as exeresis of canal content, or exeresis of pulp, tooth restoration, and denture-repair.
Tooth extractions were identified by their location in the mouth, i.e. avulsion of canine tooth, ectopic tooth, or molar tooth.
The outcomes of interest were explored as qualitative variables: binary (at least one dental treatment) or nominal variables with more than 2 categories (1, 2–3 or >3).
The explanatory variables were age and gender; these variables were assessed in the group of patients with schizophrenia and the group without schizophrenia.
Qualitative variables were expressed as percentages and were first compared between the two groups with and without schizophrenia using the Fisher exact test, under the conditions of application. The number and percentage of dental acts weres presented by class (1, 2–3, or >3) for each type of care.
The geographic scale used for this analysis was the geographic department code recorded in the EGB. France is divided into 96 metropolitan departments, with populations ranging from 77,000 to 2,577,000 inhabitants.
For each department of residence, the size of the symbol varied proportionally with the number of people with schizophrenia who resided there. Access to each type of dental care was calculated by plotting the number of overall PWS against the number of patients receiving dental care. The rate of dental care was expressed as a percentage for each category.
To estimate the association between schizophrenia and dental outcomes, multivariate logistic regressions and multivariate logistic regressions adjusted for sex were performed by age category (15–24, 25–34, 35–44, 45–54, 55–64, ≥65). The results are reported as adjusted odds ratios (aOR) with 95% confidence intervals (CI).
Two sensitivity analyses were performed for other algorithms.
First, we identified PWS from an algorithm used by the National Institute for Health Surveillance (InVS) [
F20 diagnostic codes in the register of long-term diseases associated with the F20 codes as the main or associated diagnoses in discharge abstracts (hospital data for medicine, surgery and obstetrics and/or psychiatry)
And/or at least three annual deliveries of antipsychotics in 2014 associated with the F20 ICD-10 codes as the main or associated diagnoses in discharge abstracts (hospital data for medicine, surgery and obstetrics and/or psychiatry) over the past four years.
Our algorithm did not include data from psychiatric hospitals.
Second, we identified PWS with a less restrictive algorithm, including the presence of
one of the F20 diagnostic codes in the register for long-term diseases,
and/or one of the F20 diagnostic codes as the main or associated diagnoses in discharge abstracts (hospital data for medicine, surgery and obstetrics),
and/or at least three annual deliveries of antipsychotics in 2014.
A p-value of 0.05 was set to define statistical significance for all analyses. SAS 9.3 software was used for data analyses. The geographic information system MapInfo 11.0 was used for mapping.
French university hospital researchers have a permanent authorization to manage data from the EGB as indicated in the Decree n° 2016–1871 of December 26, 2016 on processing of personal data from SNDS. Data was treated by individuals who were authorized by the State. This study was conducted in accordance with the Declaration of Helsinki. Individual written consent was not needed for this study.
In 2014, 580,219 persons over 15 years old were identified in EGB. Among them, 2,213 PWS (0.4%) were identified by our algorithm.
Every department in metropolitan France presented at least one case of schizophrenia in 2014. The departments located along a diagonal line from the north-east to the south-west had fewer cases of schizophrenia, while the highest numbers were in urban departments, those bordering the Mediterranean, and along the external borders (
Our comparison found a significant difference between PWS and persons without schizophrenia in terms of age and gender (
With schizophrenia (n = 2.213) % | Without schizophrenia (n = 578,006) % | p-value | |||
---|---|---|---|---|---|
Age | |||||
15–24 | 74 | 3.3 | 87,994 | 15.2 | |
25–34 | 339 | 15.3 | 96,254 | 16.7 | |
35–44 | 572 | 25.9 | 97,262 | 16.8 | <0.001 |
45–54 | 525 | 23.7 | 97,291 | 16.8 | |
55–64 | 428 | 19.3 | 85,459 | 14.8 | |
≥65 | 275 | 12.4 | 113,746 | 19.7 | |
Gender | |||||
Male | 1,297 | 58.6 | 281,434 | 48.7 | <0.001 |
Female | 916 | 41.4 | 296,572 | 51.3 | |
Tooth scaling | 919 | 41.5 | 277,206 | 48.0 | <0.001 |
1 | 280 | 12.7 | 90,152 | 15.6 | |
2–3 | 415 | 18.8 | 126,494 | 21.9 | <0.001 |
>3 | 223 | 10.1 | 60,560 | 10.5 | |
Dental treatments | 927 | 41.9 | 242,809 | 42.0 | 0.91 |
1 | 194 | 8.8 | 67,973 | 11.8 | |
2–3 | 323 | 14.6 | 84,637 | 14.6 | <0.001 |
>3 | 410 | 18.5 | 90,199 | 15.6 | |
Tooth extraction | 503 | 22.7 | 106,108 | 18.4 | <0.001 |
1 | 307 | 13.9 | 71,359 | 12.4 | |
2–3 | 154 | 7.0 | 30,330 | 5.2 | <0.001 |
>3 | 42 | 1.9 | 4.419 | 0.8 |
*Fisher exact test
PWS were more often male (58.6% vs 48.7%, p<0.001) and more likely to be aged 35 to 64 years.
PWS were less likely to have tooth scaling and more to have dental extraction during the 3-years follow-up period. The overall rate of tooth scaling was 41.5% for PWS and 48.0% for people without schizophrenia (p<0.0001). In PWS, the rate of tooth scaling decreased with age. There was a significant difference in the frequency of tooth extraction between the two groups: 22.7% of PWS had had at least one dental extraction versus 18.4% of people without schizophrenia (p<0.0001). The spatial distribution of tooth scaling (
In these same departments, the rate of dental extractions ranged from 6 to 23%. In eight departments, at least one dental extraction was recorded for 40 to 100% of PWS. A quarter of these departments (2/8) reported a rate of tooth scaling ranging from 0 to 28% over the study period.
The results of adjusted logistic regression analyses within 3 years are presented in
Age category | 15–24 | 25–34 | 35–44 | ||||||
OR | IC 95% | p | OR | IC 95% | p | OR | IC 95% | p | |
Tooth scaling | |||||||||
1.05 | 0.65–1.67 | 0.85 | 1.24 | 0.99–1.54 | 0.05 | 0.95 | 0.80–1.11 | 0.5 | |
1.45 | 1.41–1.49 | <0.0001 | 1.66 | 1.62–1.70 | <0.0001 | 1.53 | 1.49–1.57 | <0.0001 | |
Dental extraction | |||||||||
2.05 | 1.18–3.57 | 0.01 | 1.82 | 1.40–2.37 | <0.0001 | 1.53 | 1.26–1.87 | <0.0001 | |
1.31 | 1.26–1.37 | <0.0001 | 1.04 | 101–1.08 | 0.04 | 1.01 | 0.97–1.04 | 0.75 | |
Dental treatment | |||||||||
1.34 | 0.83–2.17 | 0.22 | 1.42 | 1.15–1.76 | 0.001 | 1.11 | 0.94–1.31 | 0.21 | |
1.24 | 1.20–1.27 | <0.0001 | 1.30 | 1.27–1.33 | <0.0001 | 1.30 | 1.27–1.34 | <0.0001 | |
Age category | 45–54 | 55–64 | ≥65 | ||||||
OR | IC 95% | p | OR | IC 95% | p | OR | IC 95% | p | |
Tooth scaling | |||||||||
0.63 | 0.53–0.75 | <0.0001 | 0.45 | 0.37–0.55 | <0.0001 | 0.42 | 0.32–0.57 | <0.0001 | |
1.52 | 1.48–1.56 | <0.0001 | 1.48 | 1.44–1.52 | <0.0001 | 1.17 | 1.14–1.19 | <0.0001 | |
Dental extraction | |||||||||
1.39 | 1.15–1.69 | 0.001 | 0.87 | 0.70–1.10 | 0.25 | 0.82 | 0.61–1.11 | 0.19 | |
0.97 | 0.94–1.00 | 0.05 | 0.98 | 0.95–1.01 | 0.11 | 0.93 | 0.90–0.95 | <0.0001 | |
Dental treatment | |||||||||
0.84 | 0.71–1.00 | 0.05 | 0.63 | 0.52–0.77 | <0.0001 | 0.7 | 0.54–0.89 | 0.005 | |
1.26 | 1.23–1.30 | <0.0001 | 1.23 | 1.20–1.23 | <0.0001 | 1.06 | 1.03–1.08 | <0.0001 |
OR: odds radio; CI: Confidence Interval; CG: Control group; Gender (ref = male)
Between 15 and 44 years, schizophrenia was not significantly associated with tooth scaling after adjustment for sex. Regression logistic analysis showed that schizophrenia was associated with decreased frequency of tooth scaling from the age of 45 years (aOR = 0.45 95% CI [0.37–0.55] for age 55–64 years). Schizophrenia was significantly associated with a higher frequency of dental treatment for 25–34 year olds (aOR = 1.42[1.15–1.76]) and a decreased frequency of dental treatment after 55 years (aOR = 0.63 95% CI [0.52–0.77] for age 55–64 years). Then, schizophrenia was associated with an increased risk of dental extraction in patients 15 to 54 years old. The presence of schizophrenia yielded an aOR of 2.05 (95% CI 1.18–3.57) for youths aged 15 to 24. After 55 years, the risk of dental extraction was not significant. Female gender was associated with more frequent tooth scaling and dental treatment, regardless of age.
To our knowledge, this study is the first to use national data to analyze the oral health treatment habits of PWS based on a large representative sample (2,213).
We highlighted certain disparities between the oral health treatment trends for PWS and for the general population. These disparities include both the type and frequency of care on a national scale.
It is well known that regular professional tooth cleaning is important for the prevention of dental caries and periodontal disease [
The social and psychological impact of dental extractions can have significant consequences on quality of life [
Compared with other types of medical care, dental visits are widely underutilized by PWS, which means that dental treatment should be delivered in a more preventive manner [
The results of the multivariate logistic regressions analysis shows that PWS who are male or older were especially likely to have less tooth scaling and more dental extraction. On the contrary, women generally had more positive oral health attitudes and practices (using extra cleaning devices for example) [
Studies that have investigated age as contributing factor in tooth scaling or dental treatment are contradictory. Advanced age contributed to less frequent tooth brushing for Harada et al. [
Recent international studies have showed that psychiatric inpatients lack sufficient preventive oral health care [
The algorithm used to identify PWS did not include the database of psychiatric hospitalizations even though it was included in the reference algorithm. This is because the EGB does not include the French psychiatric database. However, the persons who were covered as part of long-term disease with diagnostic codes F20- represent approximately 70% of people identified by the SNDS as suffering from psychotic disorders.
Furthermore, this bias is probably of limited effect. The potential consequence would be an inclusion of unidentified cases of schizophrenia in the control group, therefore reducing the amplitude of the reported associations.
One of the strengths of our study is the representativeness of the EGB of the French general population and its high stability over time. An additional strength is the fact that health insurance is compulsory for all French residents. This means that all health care acts are reimbursed, and all reimbursements are automatically recorded and transferred to the SNDS database. The quantification of dental care can therefore be considered exhaustive.
Moreover, our results suggest a spatial prevalence of schizophrenia that is tied to urbanicity. Urbanicity is a well-established environmental risk factor for developing schizophrenia [
In accordance with a number of published studies, our PWS sample was predominantly male [
This is the first study to provide geographic mapping of the oral health treatment of PWS in France. We found that the departments located along a north-east/south-west diagonal line had fewer PWS while the highest number were in urban departments, those bordering the Mediterranean, and along the external borders. We highlighted that PWS were less likely to have had tooth scaling and dental treatments but more likely to have undergone a dental extraction than general population. We noticed a clear inequity in oral health treatment, and national health policies are needed to address this issue. Further studies are needed in order to improve the management of oral health in PWS, potentially with the use of specific prevention and education programs. But first of all, the most pressing challenge is to expand the understanding of the factors that limit or facilitate the healthcare pathway for PWS in order to optimize their oral health.
The authors are grateful to Suzanne Rankin for revising the manuscript
PONE-D-19-20482
Oral health consumption habits of people with schizophrenia in France: a retrospective cohort study
PLOS ONE
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Reviewer #1: This submission is about "Oral health habits of people with schizophrenia in Franc"e. This is an analysis of a database dating back to 2014 and which may be considered as irrelevant.
The interest in an international journal is limited as shown in Figures 1-4.
The methodology is not very detailed. Under the term "oral health consumption", the authors select care variables that are not sufficiently descriptive of the accessible dental care panel. Example: "dental treatments"
The discussion is vague and does not concretely answer the objective
The references are not updated and very targeted on France.
Reviewer #2: * This article is well-written and interesting, bringing new knowledge in the epidemiological field of oral health among persons with schizophrenia.
* Title and objective. The term "consumption" might not be relevant for the present study, given that what is measured is more than just "the using up of goods and services". As explained in the introduction, PWS can have difficulties to access to treatment (which is not directly linked to the consumption). Maybe the term "treatment" would be more relevant.
* Introduction section.
- P3, l22 "These factors can include dental caries, periodontal diseases" is unnecessary, since explained factors are related to "dental caries and periodontal measurement indexes (l20).
- P3, l28-31. Please indicate in the text that ref 23 is about PWS.
- P4, l32-33: instead of "on this subject", indicate "on oral health epidemiology".
* Material and methods
- P4, l57: The paragraph should be entitled "Groups constitution", with two clear sub-paragraphs: PWS identification and control identification.
- P5, l70-1: The sentence "Follow-up dental care was explored for all people in the EGB over a period of 3 years (2014 to 2017)" should be placed in the "design of the study and sample of the population" section, because it allows to understand why the study is a retrospective cohort.
-P5, l76: please indicate that these 3 outcomes are covered by French National Insurance
-P5, l81: "The outcomes of interest were explored as qualitative variable" should rather be ""The outcomes of interest were explored as binary (at least one dental treatment) and ordinal qualitative (1,2-3 or >3) variables." Please make the changes in all the manuscript (e.g. p5, l86, etc)
- P5, l87: the Fisher exact test is OK. Pearson χ2 test is not necessary.
- P5, l88: The number and percentage of dental acts were presented ...
- P5-6: "First, PWS were localized according to their place of residence. However, mapping by residence may have compromised patient anonymity in a few cases, so we chose to map according to the department of residence." is OK, but should be removed in the text because it doesn't add meaningful information.
- P6, l96: Paragraph should be entitled "Mapping of population and distribution of dental care" , thus "We mapped the distribution of PWS and the distribution of dental care" l97 should be removed.
- P6, l102: As it is an observational study, authors should be cautious with causation. Thus, it should be written something like " To estimate the association between schizophrenia and dental outcomes, etc..."
*Results
Results are well reported
p7, l137: "confirmed" is not necessary
* Discussion
Discussion is well conducted
-p8, l180, typo "carries"
- Maybe the paragraph p8, l171-177 should appear in the limitation section of the discussion.
Figures
in the legends, please change "à" to "to"
Table 1: Presentation of p-values should be clearer. Readers should easily understand that there are two types of tests in the table (for binary outcomes and qualitative ordinal outcomes)
Table 2: Authors should keep the same definitions in the text and in the table. The labeling of "Persons without schizophrenia" is unclear.
**********
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Response to reviewers
Reviewer #1:
We thank the Reviewer for giving us an opportunity to substantially improve the content and the presentation of our manuscript. We have modified the article in accordance with your requests. You will find every modification in the text using track changes, and the pages are noted in the answer for every point below. We hope we have met your requirements to improve this paper.
This submission is about "Oral health habits of people with schizophrenia in France". This is an analysis of a database dating back to 2014 and which may be considered as irrelevant.
Response: Please consider that this retrospective study explored a follow-up dental care for a period of 3 years (2014 to 2017) for persons with schizophrenia.
The interest in an international journal is limited as shown in Figures 1-4.
The methodology is not very detailed. Under the term "oral health consumption", the authors select care variables that are not sufficiently descriptive of the accessible dental care panel. Example: "dental treatments"
Response:
We thank the Reviewer for this comment. We completed the definition of the procedures and added some examples.
In Methods section, page 5, lines 84-87:
2) Dental treatments were all procedures for filling cavities, root canal treatments, such as exeresis of canal content or exeresis of pulp, tooth restoration, and denture repair.
3) Tooth extractions were identified by their location in the mouth, i.e. avulsion of canine tooth, ectopic tooth, or molar tooth.
The discussion is vague and does not concretely answer the objective
Response: We agree with the Reviewer that the discussion needed to be revised. In particular, the first paragraph was rather vague and did not provide the main results of our paper regarding our objective. This paragraph was rewritten accordingly.
The references are not updated and very targeted on France.
Response: We thank the reviewer for this relevant comment.
We agree that our references were very targeted on France. In fact, the most recent available data on this subject on oral health epidemiology in France for the general population are more than 20 years old, except for the following reference that we included in our paper.
[15]-Bertaud-Gounot V, Kovess-Masfety V, Perrus C, Trohel G, Richard F. Oral health status and treatment needs among psychiatric inpatients in Rennes, France: a cross-sectional study. BMC Psychiatry 2013, 13:227
We also included references regarding other countries:
[46]-Di Ying Joanna Ngo, W. Murray Thomson, Mythily Subramaniam, Edimansyah Abdin,Kok-Yang Ang. The oral health of long-term psychiatric inpatients in Singapore. Psychiatry Research. 2018; 266:206-11.
[43]-Velasco‑Ortega E, Monsalve‑Guil L, Ortiz‑Garcia I, Jimenez‑Guerra A, Lopez‑Lopez J, Segura‑Egea J.J. Dental caries status of patients with schizophrenia in Seville, Spain: a case–control study. BMC Res Notes (2017) 10:50
[34]-Chu, K.-Y., Yang, N.-P., Chou, P., Chiu, H.-J., Chi, L.-Y., 2012. Comparison of oral health between
inpatients with schizophrenia and disabled people or the general population. J. Formos. Med. Assoc. 111 (4), 214–219.
[19]-Ramon, T., Grinshpoon, A., Zusman, S., Weizman, A., 2003. Oral health and treatment
needs of institutionalized chronic psychiatric patients in Israel. Eur. Psychiatry 18 (3), 101–105.
Reviewer #2:
1-This article is well-written and interesting, bringing new knowledge in the epidemiological field of oral health among persons with schizophrenia.
Response: We thank the Reviewer for giving us an opportunity to substantially improve the content and the presentation of our manuscript. We have modified the article in accordance with your requests. You will find every modification in the text using track changes, and the pages are noted in the answer for every point below. We hope we have met your requirements to improve this paper.
2-Title and objective. The term "consumption" might not be relevant for the present study, given that what is measured is more than just "the using up of goods and services". As explained in the introduction, PWS can have difficulties to access to treatment (which is not directly linked to the consumption). Maybe the term "treatment" would be more relevant.
Response: We have changed this term as requested throughout the manuscript.
* Introduction section.
3- P3, l22 "These factors can include dental caries, periodontal diseases" is unnecessary, since explained factors are related to "dental caries and periodontal measurement indexes (l20).
Response: We have deleted this sentence.
4- P3, l28-31. Please indicate in the text that ref 23 is about PWS.
Response: We made this correction in the text of the paper (page 3, line 30).
5- P4, l32-33: instead of "on this subject", indicate "on oral health epidemiology".
Response: This correction has been made (page 4, line 34).
* Material and methods
6- P4, l57: The paragraph should be entitled "Groups constitution", with two clear sub-paragraphs: PWS identification and control identification.
Response: We thank the reviewer for this suggestion and modified this paragraph accordingly.
7- P5, l70-1: The sentence "Follow-up dental care was explored for all people in the EGB over a period of 3 years (2014 to 2017)" should be placed in the "design of the study and sample of the population" section, because it allows to understand why the study is a retrospective cohort.
Response: We agree with the Reviewer. This correction was made (page 4, lines 43-44).
8-P5, l76: please indicate that these 3 outcomes are covered by French National Insurance
Response: Done (page 5, line 81).
9-P5, l81: "The outcomes of interest were explored as qualitative variable" should rather be ""The outcomes of interest were explored as binary (at least one dental treatment) and ordinal qualitative (1,2-3 or >3) variables." Please make the changes in all the manuscript (e.g. p5, l86, etc)
Response: We thank the Reviewer for this comment.
We made a mistake in the manuscript: the variables with several categories (1, 2-3 or >3) were considered as qualitative variables, and not as quantitative variables. The outcomes of interest were explored as qualitative nominal variables (binary or > 2 levels). We don’t consider the variables > 2 categories as ordinal qualitative variables. We have clarified this point in the method section.
Page 5, lines 88-90: “The outcomes of interest were explored as qualitative variables: binary (at least one dental treatment) or nominal variables with more than 2 categories (1, 2-3 or >3).”
10- P5, l87: the Fisher exact test is OK. Pearson χ2 test is not necessary.
Response: We agree, we deleted “Pearson χ2 test” in the sentence.
11- P5, l88: The number and percentage of dental acts were presented ...
We thank the Reviewer for this suggestion. We modified the sentence accordingly:
Page 6, lines 96-97 “The number and percentage of dental acts were presented by class (1, 2-3, or >3) for each type of care.”
12- P5-6: "First, PWS were localized according to their place of residence. However, mapping by residence may have compromised patient anonymity in a few cases, so we chose to map according to the department of residence." is OK, but should be removed in the text because it doesn't add meaningful information.
Response: This correction was made
13- P6, l96: Paragraph should be entitled "Mapping of population and distribution of dental care" , thus "We mapped the distribution of PWS and the distribution of dental care" l97 should be removed.
Response: This correction was made.
14- P6, l102: As it is an observational study, authors should be cautious with causation. Thus, it should be written something like " To estimate the association between schizophrenia and dental outcomes, etc..."
Response: We thank the Reviewer for this comment. We have made the change as requested (page 6, line 111).
*Results: Results are well reported
15- p7, l137: "confirmed" is not necessary
Response: We deleted “confirmed” as requested
* Discussion: Discussion is well conducted
16 -p8, l180, typo "carries"
Response: Thank you for pointing this error which was corrected.
17- Maybe the paragraph p8, l171-177 should appear in the limitation section of the discussion.
Response: We agree with this suggestion. We moved this sentence from the beginning of the “discussion” section to the” limitation” subsection (page 12, lines 294-300).
Figures
18-in the legends, please change "à" to "to"
Response: Thank you for pointing this error which was corrected.
19-Table 1: Presentation of p-values should be clearer. Readers should easily understand that there are two types of tests in the table (for binary outcomes and qualitative ordinal outcomes).
As mentioned before, we have considered all the variables as qualitative nominal variables. We have used the Pearson Chi² test or the Fisher exact test, under the conditions of application. The Fischer exact test was added in the table, as you indicated that the Pearson Chi² test was not necessary.
20-Table 2: Authors should keep the same definitions in the text and in the table. The labeling of "Persons without schizophrenia" is unclear.
Response: We agree with this suggestion. We removed "Persons without schizophrenia” and have replaced it by “Control Group”.
Submitted filename:
Oral health treatment habits of people with schizophrenia in France: a retrospective cohort study
PONE-D-19-20482R1
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PONE-D-19-20482R1
Oral health treatment habits of people with schizophrenia in France: a retrospective cohort study
Dear Dr. Denis:
I am pleased to inform you that your manuscript has been deemed suitable for publication in PLOS ONE. Congratulations! Your manuscript is now with our production department.
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