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Oral health among HIV-positive and HIV-negative children in Phnom Penh, Cambodia: a cross-sectional study

Background HIV-positive children are at high risk for oral mucosal disorders. Additionally, their low immune status is associated with dental caries. However, little is known about how their dental caries and related risk factors, such as salivary flow, salivary pH level and oral health-related quality of life, differ from those of HIV-negative children. The study aimed to assess (1) dental caries and related risk factors in HIV-positive compared with HIV-negative children and (2) the association between these factors and HIV seropositive status in Phnom Penh, Cambodia. Methods This was a cross-sectional study conducted as a baseline survey of a randomised controlled trial. The study setting was the National Pediatric Hospital’s catchment area. The study population comprised 328 HIV-positive and 154 HIV-negative children aged 3–15 years and their caregivers. We collected clinical oral health data, questionnaire data to assess oral health-related quality of life and growth data. Results The mean number of decayed, missing or filled permanent teeth (DMFT) and deciduous teeth (dmft) among HIV-positive children was 4.0 (SD 3.6) and 7.0 (SD 4.9), respectively. Among HIV-negative children, the respective values were 3.3 (SD 3.7) and 7.1 (SD 4.6). Living with HIV was positively associated with DMFT (adjusted OR 1.85, 95% CI 1.14 to 3.01) and salivary flow (β=0.72, 95% CI 0.44 to 1.00) and negatively associated with salivary pH (β=−0.13, 95% CI −0.24 to –0.02). However, HIV-positive status was not significantly associated with dmft or oral health-related quality of life. Conclusions HIV-positive children had poorer oral health status regarding DMFT and salivary pH level. Specific strategies and further efforts are required to align their oral health status with that of HIV-negative children.


GENERAL COMMENTS
Methods: Sample size (n) is given to be 480 (including 320 HIV positive and 160 HIV negative children) but in Table 1 sample size (n) is 482. Why was an intervention group of 160 HIV positive children created when no intervention was given? Since it is a cross sectional study (not an interventional study), it should not have more than two groups-one HIV positive and other HIV negative (control).
No need of mentioning about the research protocol for the randomized control trial study. For various factors recorded like-Diet chart, brushing etc. as in Table 1, there should be a mention of these along with salivary pH and Flow in Methods.
Results: Too much of extra data has been given like-Health status (height, weight), HRQoL, which is not required as per the Aims and Objectives of the present study.

Responses to Reviewer
Manuscript ID: bmjpo-2020-000992 Title: Oral health among HIV-positive and HIV-negative children in Phnom Penh: A cross-sectional study Reviewer: 1 1. Page 6, line 18: Unclear if one of the two control groups (i.e. HIV-positive children) played any role in sample size calculations. Please clarify.
Response: This study was conducted as a baseline survey of the randomized controlled trial, and it was necessary to consider the calculation of two control groups because of the study design to compare the viral load between HIV-positive intervention and control groups. However, we have re-analyzed the power based on the sample collected and revised the text accordingly. Please see the "sample size" section on page 5.
2. Page 6, line 20: Please specify the power, alpha level, and the minimum detectable difference that were used in determining the sample size. Also, clarify which endpoint are the sample size calculations based upon. Response: Please see our response to query #1.
3. Page 6, line 25: When the sample size was reduced from 260 per group to 160 per group how much was the drop in statistical power? This needs to be elaborated Response: Please see our response to query #1.
4. Page 8, page 14: Please replace "multivariate" with "multivariable", a more appropriate statistical term Response: "Multivariate" on page 8 was a typo and has been revised appropriately. However, we were unable to locate "multivariate" on page 14. If the reviewer would be willing to identify the exact location, we will correct it.
5. Page 8, line 21: You need to explain why the median DMFT was chosen over other cut-off points (e.g. say 90th percentile). Is there a validated study demonstrating that this cut-off is clinically relevant? If yes, please cite it Response: There is no validated cut-off point for DMFT, and previous studies use different cut-off points such as the median and mean. We used the median for this reason and also because the DMFT was not normally distributed in our study. We have added these explanations to the text. Please see line 6 on page 7.
6. Page 13, line 50: In your multiple logistic regression to evaluate the effect of HIV on DMFT did you adjust for BMI, emotional functioning, school functioning, and self-estimation of the health of teeth (as shown in Table 2)? If so, your model might be biased if these covariates are affected by children's HIV status (which seems to be the case here). You might want to consider tools like http://dagitty.net/ to guide you with appropriate selection of covariates in your model Response: Thank you for your suggestion and recommendation of these tools. We included not only the variables associated with HIV status, but also related to dental caries, as well as age and sex. We have mentioned this in lines 7-9 on page 7.
Reviewer: 2 1. Methods: Sample size (n) is given to be 480 (including 320 HIV positive and 160 HIV negative children) but in Table 1 sample size (n) is 482. Response: Thank you for your comments. Please see our response to query #1.

Why was an intervention group of 160 HIV positive children created when no intervention was given?
Since it is a cross sectional study (not an interventional study), it should not have more than two groups-one HIV positive and other HIV negative (control).
Response: This study used the data from a baseline survey of a randomized controlled trial, as mentioned in the study design. The sample size was calculated based on the original study. Thus, we mentioned information about the intervention group in the sample size calculation. To avoid confusion, we have added the following explanation in the sample size section: "This study was conducted as a baseline survey of a randomized controlled trial. The sample size was calculated in advance for the original study, which is presented in the protocol." Please see lines 2-4 on page 5.
3. No need of mentioning about the research protocol for the randomized control trial study. Response: Thank you for your comment, but as this study was conducted as a baseline for a randomized controlled trial, we thought it necessary to mention it. The details of the sample size calculation are included in the protocol, and given this, we shortened the sample size section as the Editor-in-chief suggested.
4. For various factors recorded like-Diet chart, brushing etc. as in Table 1, there should be a mention of these along with salivary pH and Flow in Methods. Response: The reviewer's suggestion is totally correct. However, the journal indicates a word count limit of 2500, and it was necessary for us to shorten the description of the questions that were not directly related to the study aims and objectives. However, we have added the references for the questions in the text. Please see line 29, page 5.

Results
: Too much of extra data has been given like-Health status (height, weight), HRQoL, which is not required as per the Aims and Objectives of the present study. Response: We have removed the data accordingly. Please see lines 6 to 8 on page 8.
Reviewer: 3 1. The manuscript contains important information on the oral health status of HIV patients. On the other hand, it compared the other outcomes in a comparison group. The study designed very well. However, the manuscript needs more revision specially in discussion part to elaborate the findings well-structured and according to rules of scientific writing with shorter paragraphs and separate subjects in each paragraph.
Response: Thank you for the comments. We believe that we elaborated the findings well, based on the various and repeated feedback from the co-authors with expertise in academic writing and the professional staff of an English-scientific editing company. If the reviewer could indicate specific sections that require revision, we will consult the editorial service again for specific revisions that would meet the reviewer's expectation.
2. Oral health and children can be added to keywords. Response: We have added oral health and children to the keywords.
3. Please revise the text for reference numbers through the text (references should be superscript and…) Response: We are sorry, but we could add only the listed terms, and "oral health" and "children" were not on the list.
Editor in Chief 1. Title add "Cambodia" after "Phnom Penh" Response: We have added "Cambodia" after "Phnom Penh." 2. Add the questionnaire as an appendix.