Dental Treatment Needs and Cost Burden Among Older Adults: A K-Means Cluster Analysis to Inform Oral Health Policies
Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsDear Authors,
The notes below summarize my thoughts on the article.
1. The country name in the text is "Turkey," but to my knowledge, it should be "Türkiye."
2. How did you calculate the sample size for the study? Did you perform a power analysis? Is the distribution of age groups statistically appropriate? Please explain in the text.
3. Could combining samples aged 75 and over into a single group have affected comparisons with studies conducted in three separate age groups?
4. The treatment alternatives described in line 88, such as partial dentures or implants, which are also applied to the elderly, are not included. Were treatment alternatives offered to the patients? The patients' economic situation may have been a more decisive factor in these choices. It would have been appropriate to include the patients' economic situation in the evaluation. I suggest you mention this in the limitations.
5. Please explain the abbreviations used in the tables below the tables. Furthermore, the meaning of the bold letters, the significant level, and the statistics used should be stated.
6. What is the prevalence mentioned in line 229? Please provide a reference.
7. Provide a reference for the prevalence of prosthetic needs mentioned in line 250.
8. The studies on treatment prices in state institutions in line 286 are generalized. There are many dental treatment options that state-owned health institutions do not pay for or provide. In addition, the minimum price tariff used in the private sector is different. Moreover, SSI does not provide support for treatments performed here. Therefore, this situation should be stated in the limitations.
9. Descriptive statistics provide data on marital status and gender, but they do not state whether these parameters have a statistical effect.
10. Half of the references are older than 10 years. Six articles are older than 20 years. There are doubts about the reliability of articles 10 and 23. I recommend supporting the study with more recent and reliable references.
11. I suggest rewriting the conclusion section.
12. The introduction section could highlight the effects of aging on oral and dental health. A summary of previous studies conducted worldwide and in Türkiye could be provided. More discussion could be given on K-means algorithm studies.
13. Keywords should be chosen to be appropriate for MeSH (Medical Subject Headings). This will increase the visibility of the study.
Author Response
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Author Response File: 
Author Response.pdf
Reviewer 2 Report
Comments and Suggestions for AuthorsI would like to congratulate the authors on this study. The topic of older people and the costs associated with oral health issues is highly important and relevant. However, I have several suggestions and comments.
The Introduction section is too short and does not provide sufficient background on the topic. In particular, you have not adequately addressed the broader problem and its significance, which is essential for understanding the context and importance of the study.
Please include relevant studies from your geographical region to strengthen the background and provide better context for the local significance of the problem. Regional data are important because oral health challenges, access to dental care, and socioeconomic factors may differ substantially across countries and populations. In addition, the authors should more clearly emphasize why this study is important. The Introduction should better explain the clinical and public health relevance of the topic, particularly considering that poor oral health in older adults is strongly associated with reduced quality of life, nutritional deficiencies, systemic diseases, and increased healthcare burden. Highlighting these aspects would help readers better understand the rationale and contribution of the study.
The manuscript does not mention the minimum sample size calculation, which is an important methodological issue. The authors should clarify whether it was performed and provide the main parameters used. Without this information, it is difficult to assess whether the study had sufficient statistical power.
The very limited number of participants in the ≥85 years group (n = 6, 2.4%) should be clearly highlighted as a major limitation of the study. Such a small subgroup significantly reduces the reliability and generalizability of the findings for the oldest population, which is particularly important considering that this age group often has the highest burden of oral health problems and treatment needs.
The Discussion section does not clearly address the limitations of the study.
Author Response
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Author Response File: Author Response.pdf
Reviewer 3 Report
Comments and Suggestions for AuthorsThe manuscript addresses an important and timely public health topic, namely the relationship between dental treatment needs and the associated cost burden in older adults. The subject is relevant, and the attempt to combine clinical needs with economic evaluation is commendable. However, in its current form, the manuscript presents several methodological and interpretative limitations that need to be addressed before it can be considered for publication.
First, the study is based on a single-center retrospective dataset including 250 patients. While the authors acknowledge this aspect, the implications are not sufficiently explored. The use of a census approach limited to patients who completed treatment may introduce a selection bias, potentially excluding individuals with more severe conditions or limited financial access to care. Additionally, the data were collected between 2018 and 2020, which raises concerns about the current relevance of the findings, especially in the context of post-pandemic healthcare changes. These aspects should be discussed more explicitly in the limitations section.
The use of K-means cluster analysis is interesting and adds value to the study; however, its implementation is insufficiently justified. The manuscript does not explain how the number of clusters (k=2) was determined, nor does it provide any validation metrics such as silhouette scores or similar methods. Without this information, it is difficult to assess the robustness and clinical relevance of the clustering results. A more detailed explanation of the clustering methodology and its validation is necessary.
The interpretation of the results also requires refinement. The authors conclude that relatively younger older adults (65–74 years) present higher treatment complexity and cost burden. While this is supported by the data, the explanation provided is somewhat simplistic. This finding may reflect the presence of more remaining teeth and therefore more treatable structures, rather than inherently worse oral health. It could also be influenced by differences in healthcare utilization patterns. The discussion should be revised to better contextualize these findings and avoid overinterpretation.
Regarding the cost analysis, although the use of CPI adjustment and PPP conversion is appropriate, the methodology is not described in sufficient detail. It remains unclear how costs were standardized across different procedures and whether all relevant cost components were included. A clearer, step-by-step description of the cost calculation process would improve transparency and reproducibility.
There are also some issues related to data presentation. For example, in Table 1, radiological treatments appear to have the highest frequency (98.4%), yet the text refers to periodontology as the most prevalent category, which creates confusion. Additionally, the tables are quite dense and may benefit from simplification or clearer structuring. In Table 2, multiple statistical comparisons are performed without any mention of correction for multiple testing, which should be addressed.
The discussion section, while comprehensive, tends to be descriptive and closely reiterates the results. It would benefit from a more critical approach, including stronger integration with existing literature and a deeper exploration of the implications for health policy and gerodontology practice. Expanding on how these findings could be translated into concrete policy or clinical strategies would significantly enhance the impact of the manuscript.
Overall, the study has potential, but substantial revisions are required to improve methodological transparency, statistical rigor, and interpretative depth.
Author Response
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Author Response File: Author Response.pdf
Reviewer 4 Report
Comments and Suggestions for AuthorsThe manuscript addresses a relevant public health issue by analyzing dental treatment needs and associated cost burdens in older adults using a clustering approach. The topic is timely and aligned with the increasing demand for evidence-based oral health policy planning in ageing populations. The use of PPP-adjusted costs and the attempt to identify cost profiles through K-means clustering are methodological strengths that enhance the policy relevance of the study.
However, several aspects require improvement to reach publication standards:
From a methodological standpoint, although the study is clearly described as retrospective and census-based, the lack of probabilistic sampling limits the external validity of the findings. This should be explicitly acknowledged as a constraint on generalizability, emphasizing that results are context-specific to a single institutional setting. Additionally, the rationale for selecting two clusters in the K-means analysis is insufficiently justified. There is no report of cluster validation metrics, which weakens the robustness of the clustering solution.
The statistical analysis section would benefit from greater clarity and rigor. While non-parametric tests are appropriately used, the manuscript does not fully explain how multiple comparisons were handled or whether any correction was applied. Moreover, the interpretation of associations remains largely descriptive and could be strengthened with a more analytical framework.
In the Results section, the presentation is generally clear; however, there are minor inconsistencies and redundancies. For example, the description of treatment needs contains a discrepancy where radiology is incorrectly reported as the highest need (98.4%) while later referred to as periodontology. Tables are informative but could be streamlined to avoid repetition between text and tabulated data. Some p-values are inconsistently formatted (e.g., commas instead of decimal points), which should be standardized.
The Discussion is comprehensive and well-supported by the literature, but it occasionally overextends interpretations beyond the data. Specifically, policy implications and causal inferences should be toned down, given the observational and non-probabilistic nature of the dataset. The manuscript would benefit from a clearer distinction between empirical findings and interpretative commentary.
Author Response
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Author Response File: Author Response.pdf
Round 2
Reviewer 3 Report
Comments and Suggestions for AuthorsThank you for your careful revision of the manuscript entitled “Dental Treatment Needs and Cost Burden Among Older Adults: A K-Means Cluster Analysis for Oral Health Policies.”
The team has substantially improved the revised version. In particular, the Introduction now provides a clearer public health rationale and a more appropriate contextualization of geriatric oral healthcare needs in Türkiye. The methodological section has also been strengthened through additional clarification regarding patient inclusion, procedure-level cost aggregation, inflation and PPP adjustment, and the rationale for using K-means clustering. Furthermore, the addition of the elbow-method justification for the two-cluster solution improves the transparency of the analytical approach. The expanded Discussion and limitations section now provide a more balanced interpretation of the results, particularly regarding the single-center design, the public-sector reimbursement context, potential selection bias, and the limited generalizability of the findings.
Overall, the major scientific and methodological concerns have been adequately addressed. The manuscript is relevant to the scope of the journal and provides useful evidence regarding treatment complexity, cost burden, and the importance of preventive oral healthcare strategies among older adults.
Before publication, I recommend only the following very minor editorial corrections:
Materials and Methods, lines 120–124: the sentence “The study included data from 250 older adults aged ≥65 … who completed treatment between.” is incomplete. Please revise this sentence by clearly incorporating the study period, for example: “The study included data from 250 older adults aged ≥65 years who completed treatment between September 2018 and March 2020.”
Table 4: under Out-of-Pocket Payments – Periodontology, the value reported for Cluster 1 appears as 132.46 without a corresponding standard deviation, although the table indicates that values are presented as mean ± SD. Please verify and complete this entry.
Please replace all occurrences of p = 0.000 with the statistically appropriate notation p < 0.001 throughout the manuscript and tables.
These issues are minor and do not affect the validity of the study design, statistical analysis, interpretation of the results, or the overall conclusions of the manuscript.
Recommendation: Accept in Present Form, subject to minor editorial corrections prior to publication.
Comments on the Quality of English LanguageA final English-language proofreading is recommended to correct a small number of residual typographical or grammatical issues, including:
Line 15: “due to ageing populations and increasing their treatment needs”;
Line 60: “They also affect both physical and psychosocial well-being in older adults as well as quality of life, negatively”;
Line 224: “commonly ssen”;
Lines 274–276: “with an mean” should be changed to “with a mean”;
Lines 295–300: expressions such as “The most commonly procedure” and “the most commonly treatments were” should be grammatically revised.
Please ensure terminological consistency throughout the manuscript, particularly regarding the use of “prosthodontics,” “prosthetic treatment,” and “prosthetic rehabilitation.”
Author Response
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Author Response File: Author Response.pdf
