Letter Regarding “The Relationship Between Preventive Dental Care and Overall Medical Expenditures”

Am J Manag Care. 2026;32(9):In Press

Takeaway Points

• Preventive health services are widely assumed to reduce downstream health care use and costs, but this assumption requires careful validation.
• Many existing studies are observational and prone to unmeasured confounding.
• Associations reported in prior research may overestimate true causal effects.
• Quasi-experimental designs, especially instrumental variable methods, help address hidden bias.

I read with great interest the recent article by Taylor et al published in The American Journal of Managed Care, which examined the impact of preventive health services on broader medical outcomes.¹ I am writing to highlight the continued importance of strengthening methodological rigor in studies assessing the impact of preventive health services on broader medical outcomes. Preventive dental care has long been assumed to reduce downstream health care utilization and costs.^2,3 Yet recent work underscores the need for more cautious interpretation of these assumptions and greater attention to study design when drawing causal conclusions.⁴

A growing number of analyses have attempted to link preventive interventions to reduced emergency visits, lower hospitalization rates, and lower overall medical expenditures.^5-7 Although these findings are promising, many existing studies remain observational and are therefore vulnerable to unmeasured confounding. For instance, individuals who seek preventive services tend to be more health conscious, more adherent to medical advice, and more engaged with the health care system in general.^8,9 These characteristics alone can influence medical expenditures, independent of the preventive service being evaluated.

For this reason, quasi-experimental approaches—particularly instrumental variable methods—are essential for addressing bias arising from unobserved factors. Studies employing valid instruments can provide a clearer understanding of the true causal effect of preventive services. Importantly, recent research has demonstrated that when such methods are applied, previously assumed cost-reducing effects may diminish or disappear, suggesting that earlier evidence may overestimate benefits due to selection bias.¹⁰

These findings should not be interpreted as diminishing the inherent value of preventive care, which remains essential for improving health and quality of life. Rather, Taylor et al caution against assuming short-term cost savings: They found no statistically significant reduction in medical or pharmacy expenditures associated with preventive dental visits among Medicaid enrollees.¹ Accordingly, public insurance policies should not rely on expected cost offsets as the primary rationale for covering preventive services.¹

I encourage continued investment in high-quality research designs—such as randomized trials, quasi-experimental approaches (eg, instrumental variable or difference-in-differences analyses), and longer-term longitudinal studies—to better inform prevention-related policy and resource allocation. Such evidence is particularly critical for decision-makers in state Medicaid agencies, federal bodies such as CMS, and legislative stakeholders who determine coverage and reimbursement policies for preventive services.

Acknowledgments

The author declares that generative artificial intelligence was used in the creation of this manuscript. The author would like to thank OpenAI for assistance with sentence adjustment of this letter.

Author Affiliation: Suzhou Wujiang District Hospital of Traditional Chinese Medicine, Suzhou, Jiangsu, China.

Source of Funding: None.

Author Disclosures: The author reports no relationship or financial interest with any entity that would pose a conflict of interest with the subject matter of this article.

Authorship Information: Concept and design; drafting of the manuscript; critical revision of the manuscript for important intellectual content; administrative, technical, or logistic support; and supervision.

Address Correspondence to: Jiayi Chen, MDS, Suzhou Wujiang District Hospital of Traditional Chinese Medicine, Dachun Road 999, Suzhou, Jiangsu 215221, China. Email: cjy13912736738@163.com.

REFERENCES

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2. Nasseh K, Vujicic M, Glick M. The relationship between periodontal interventions and healthcare costs and utilization: evidence from an integrated dental, medical, and pharmacy commercial claims database. Health Econ. 2017;26(4):519-527. doi:10.1002/hec.3316

3. Lamster IB, Malloy KP, DiMura PM, et al. Dental services and health outcomes in the New York State Medicaid program. J Dent Res. 2021;100(9):928-934. doi:10.1177/00220345211007448

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7. Yamagishi K, Sankai T, Muraki I, et al. Trends in stroke, cardiovascular disease, and medical expenditure under a community-based long-term stroke prevention program. J Hypertens. 2023;41(3):429-436. doi:10.1097/HJH.0000000000003351

8. Delnevo CD, Steinberg MB, Abatemarco DJ, Hausman AJ. Correlates of clinical preventive practices among internal medicine residents. Prev Med. 2003;36(6):645-651. doi:10.1016/s0091-7435(03)00041-0

9. Patrick AR, Shrank WH, Glynn RJ, et al. The association between statin use and outcomes potentially attributable to an unhealthy lifestyle in older adults. Value Health. 2011;14(4):513-520. doi:10.1016/j.jval.2010.10.033

10. Canan C, Lesko C, Lau B. Instrumental variable analyses and selection bias. Epidemiology. 2017;28(3):396-398. doi:10.1097/EDE.0000000000000639