Economic evaluations in water-fluoridation: a scoping review

Socioeconomic vulnerability and access to community water fluoridation in Washington

BACKGROUND

The aim of the authors was to determine whether socioeconomic vulnerability is associated with community water fluoridation (CWF).

METHODS

The authors used US Census Bureau data to create 4 county-level vulnerability markers (percentages non-White, Hispanic or Latino, below the federal poverty threshold, education below high school), obtained county-level CWF data from the Washington State Department of Health, and evaluated associations using Spearman rank correlation coefficient and the Kruskal-Wallis rank sum test. The authors then interviewed 122 community members in Washington (December 2022-March 2023) and analyzed the interview data inductively.

RESULTS

A higher percentage of non-White people at the county level was associated with a significantly higher level of CWF (Spearman rank correlation coefficient, 0.55; 95% CI, 0.29 to 0.82; P < .001), whereas county-level poverty was associated with significantly lower CWF (Spearman rank correlation coefficient, -0.36; 95% CI, -0.70 to -0.03; P = .02). High school completion was not associated with county-level CWF. Significantly larger proportions of Hispanics and Latinos lived in counties with higher CWF (P < .05). From the interviews, more participants thought tap water was healthy than unhealthy, but 41% had mixed feelings. Similarly, more participants thought CWF was acceptable than unacceptable, with 35% reporting mixed feelings. Negative views about tap water and CWF were more common among non-White participants.

CONCLUSIONS

People in racially and ethnically diverse communities in Washington appear to have greater access to CWF, whereas those in lower-income communities have poorer access.

PRACTICAL IMPLICATIONS

CWF is an important population-level strategy to prevent caries. Additional work is needed to improve access to CWF, especially for people from low-income communities.

Economic evaluation of a water fluoridation scheme in Cumbria, UK

OBJECTIVES

The addition of fluoride to community drinking water supplies has been a long-standing public health intervention to improve dental health. However, the evidence of cost-effectiveness in the UK currently lacks a contemporary focus, being limited to a period with higher incidence of caries. A water fluoridation scheme in West Cumbria, United Kingdom, provided a unique opportunity to study the contemporary impact of water fluoridation. This study evaluates the cost-effectiveness of water fluoridation over a 5-6 years follow-up period in two distinct cohorts: children exposed to water fluoridation in utero and those exposed from the age of 5.

METHODS

Cost-effectiveness was summarized employing incremental cost-effectiveness ratios (ICER, cost per quality adjusted life year (QALY) gained). Costs included those from the National Health Service (NHS) and local authority perspective, encompassing capital and running costs of water fluoridation, as well as NHS dental activity. The measure of health benefit was the QALY, with utility determined using the Child Health Utility 9-Dimension questionnaire. To account for uncertainty, estimates of net cost and outcomes were bootstrapped (10 000 bootstraps) to generate cost-effectiveness acceptability curves and sensitivity analysis performed with alternative specifications.

RESULTS

There were 306 participants in the birth cohort (189 and 117 in the non-fluoridated and fluoridated groups, respectively) and 271 in the older school cohort (159 and 112, respectively). In both cohorts, there was evidence of small gains in QALYs for the fluoridated group compared to the non-fluoridated group and reductions in NHS dental service cost that exceeded the cost of fluoridation. For both cohorts and across all sensitivity analyses, there were high probabilities (>62%) of water fluoridation being cost-effective with a willingness to pay threshold of £20 000 per QALY.

CONCLUSIONS

This analysis provides current economic evidence that water fluoridation is likely to be cost-effective. The findings contribute valuable contemporary evidence in support of the economic viability of water fluoridation scheme.

The CATFISH study: An evaluation of a water fluoridation program in Cumbria, UK

OBJECTIVES

The objective was to assess the effectiveness of a Water Fluoridation program on a contemporary population of children.

METHODS

The study used a longitudinal prospective cohort design. In Cumbria, England, two groups of children were recruited and observed over a period of 5-6 years. The Birth Cohort consisted of families recruited from two hospitals in Cumbria where children were conceived after water fluoridation was reintroduced. The systemic and topical effects of community water fluoridation were evaluated in the Birth Cohort. The Older Cohort were approximately 5 years old and recruited from primary schools in Cumbria, shortly after water fluoridation was reintroduced. The predominantly topical effects of fluoridated water were evaluated in the Older Cohort. The primary outcome was the proportion of children with clinical evidence of caries experience in their primary (Birth Cohort) or permanent teeth (Older Cohort). Unadjusted and adjusted regression models were used for analysis.

RESULTS

The final clinical examinations for the Birth Cohort involved 1444 participants (mean age 4.8 years), where 17.4% of children in the intervention group were found to have caries experience, compared to 21.4% in the control group. A beneficial effect of water fluoridation was observed adjusting for deprivation (a socioeconomic measure), sex, and age, (adjusted odds ratio 0.74 95% CI 0.55 to 0.98). The final Older Cohort clinical examinations involved 1192 participants (mean age 10.8 years) where 19.1% of children in the intervention group were found to have caries experience compared to 21.9% in the control group (adjusted odds ratio 0.80, 95% CI 0.58 to 1.09). For both the Birth Cohort and Older Cohort there was evidence of a beneficial effect on dmft/DMFT count (IRR 0.61, 95% CI 0.44, 0.86) and (IRR 0.69, 95% CI 0.52, 0.93) respectively. No conclusive proof was found to indicate that the effectiveness of water fluoridation differed across area deprivation quintiles.

CONCLUSIONS

In the contemporary context of lower caries levels and widespread use of fluoride toothpaste, the impact of water fluoridation on the prevalence of caries was smaller than previous studies have reported. It is important to consider the clinical importance of the absolute reduction in caries prevalence against the use of other dental caries preventive measures.

Socio-economic status and access to fluoridated water in Queensland: an ecological data linkage study

OBJECTIVES

To investigate the relationship between access to fluoridated drinking water and area-level socio-economic status in Queensland.

STUDY DESIGN

Ecological, geospatial data linkage study.

SETTING

Queensland, by statistical area level 2 (SA2), 2021.

MAIN OUTCOME MEASURES

Proportion of SA2s and of residents with access to fluoridated drinking water (natural or supplemented); relationship at SA2 level between access to fluoridated water and socio-economic status (Index of Relative Socio-economic Advantage and Disadvantage, IRSAD; Index of Economic Resources, IER).

RESULTS

In 2021, an estimated 4 050 168 people (79.4% of the population) and 397 SA2 regions (72.7%) in Queensland had access to fluoridated water. Access was concentrated in the southeastern corner of the state. After adjusting for SA2 population, log area, and population density, the likelihood of access to fluoridated drinking water almost doubled for each 100-rank increase in IRSAD (adjusted odds ratio [aOR], 1.93; 95% confidence interval [CI], 1.59-2.36) or IER (aOR, 1.77; 95% CI, 1.50-2.11).

CONCLUSIONS

The 2012 decision to devolve responsibility for water fluoridation decisions and funding from the Queensland government to local councils means that residents in lower socio-economic areas are less likely to have access to fluoridated water than those in more advantaged areas, exacerbating their already greater risk of dental disease. Queensland water fluoridation policy should be revised so that all residents can benefit from this evidence-based public health intervention for reducing the prevalence of dental caries.

National and Subnational Trend of Dental Caries of Permanent Teeth in Iran, 1990-2017

OBJECTIVE

There are currently no integrated data on the trend of dental caries amongst distinct age groups in Iran. We aimed to assess the national and subnational trend of dental caries of permanent teeth in Iran from 1990 to 2017.

METHODS

A literature search about dental caries and the decayed-missing-filled teeth index (DMFT) was performed in PubMed, Web of Science, Scopus, and 3 national databases (in Persian). All eligible national oral health surveys in these 28 years were included. We categorised and aggregated the DMFT values and their components based on age (5-year-based groups from 5 to 9 to 60+ years), sex, year, and province. The data for missing spots were estimated using the spatiotemporal Bayesian hierarchical model. We used the bootstrap method in multilevel models to predict the uncertainty interval (UI) of the modelled results.

RESULTS

Nationally, the all-ages mean DMFT increased by nearly 58.0% (6.8 [95% UI, 4.1-10.5] in 1990 to 10.8 [95% UI, 7.5-14.5] in 2017). Decayed teeth (DT) and missing teeth (MT) rose by 84.5% and 31.6% during this period, respectively. Filled teeth (FT) showed almost a 2.6-fold increase in the same period from 0.6 (95% UI, 0.01-1.6) in 1990 to 1.7 (95% UI, 0.6-2.8) in 2017. The proportion of DT and FT continuously increased in both sexes. In 2017, the highest DT, MT, and FT were estimated in the 25-29 (4.9 [95% UI, 2.5-7.2]), 60+ (21.5 [95% UI, 17.5-25.4]), and 35-39 (2.6 [95% UI, 1.3-4.0]) year age groups.

CONCLUSIONS

Caries of permanent dentition levies a growing burden on the Iranian population. Considering the continuous increase in caries during the 1990-2017 period, Iranian policymakers should pay heed to these findings and react more proactively to mitigate this perpetuating issue. Implementing nationwide interventions such as sugar consumption management should be encouraged to achieve sustainable outcomes in this regards.

A review of water fluoridation studies and the effect on dental caries and treatment costs, undertaken in Scotland

Objectives This review aimed to investigate the effect of water fluoridation on the dental health of Scottish people by comparing results of starting and discontinuing fluoridation in Scotland.Data sources Data sources were retrieved from electronic databases. The grey literature was also searched. Articles were selected if the population of interest was Scottish. The objective was to evaluate the influence of water fluoridation on dental caries using the dmft/s, DMFT/S (decayed, missing and filled teeth/surfaces) or deft/s indices (decayed, extraction needed, filled teeth/surfaces).Data extraction Name of the authors, publication years, location of the study, sample size, type of study design, age of participants, method of assessing the outcome, data related to the exposure and the outcome, and the overall result of each study were extracted. The data were collected based on the effect of water fluoridation and its cessation on dental caries and the type of dentition.Results Nine studies were included in the review. The findings revealed that the introduction of water fluoridation led to reductions in caries. Moreover, after the cessation of fluoridation, caries levels continued to remain lower in the fluoridated groups. Additionally, fluoridation had the effect of reducing the cost of dental treatment.Conclusion Water fluoridation was effective in improving dental caries among the Scottish child population. New studies are required to provide contemporary evidence for water fluoridation in Scotland.

Systematic review of epidemiological and toxicological evidence on health effects of fluoride in drinking water

INTRODUCTION

Fluoride is a naturally occurring substance that is also added to drinking water, dental hygiene products, and food supplements for preventing dental caries. Concerns have been raised about several other potential health risks of fluoride.

OBJECTIVE

To conduct a robust synthesis of evidence regarding human health risks due to exposure to fluoride in drinking water, and to develop a point of departure (POD) for setting a health-based value (HBV) for fluoride in drinking water.

METHODS

A systematic review of evidence published since recent reviews of human, animal, and in vitro data was carried out. Bradford Hill considerations were used to weigh the evidence for causality. Several key studies were considered for deriving PODs.

RESULTS

The current review identified 89 human studies, 199 animal studies, and 10 major in vitro reviews. The weight of evidence on 39 health endpoints was presented. In addition to dental fluorosis, evidence was considered strong for reduction in IQ scores in children, moderate for thyroid dysfunction, weak for kidney dysfunction, and limited for sex hormone disruptions.

CONCLUSION

The current review identified moderate dental fluorosis and reduction in IQ scores in children as the most relevant endpoints for establishing an HBV for fluoride in drinking water. PODs were derived for these two endpoints, although there is still some uncertainty in the causal weight of evidence for causality for reducing IQ scores in children and considerable uncertainty in the derivation of its POD. Given our evaluation of the overall weight of evidence, moderate dental fluorosis is suggested as the key endpoint until more evidence is accumulated on possible reduction of IQ scores effects. A POD of 1.56 mg fluoride/L for moderate dental fluorosis may be preferred as a starting point for setting an HBV for fluoride in drinking water to protect against moderate and severe dental fluorosis. Although outside the scope of the current review, precautionary concerns for potential neurodevelopmental cognitive effects may warrant special consideration in the derivation of the HBV for fluoride in drinking water.

Evaluation of water fluoridation scheme in Cumbria: the CATFISH prospective longitudinal cohort study

Background

Water fluoridation was introduced in the UK against a background of high dental decay within the population. Levels of decay have dramatically reduced over the last 40 years following widespread use of fluoride toothpaste.

Objective

The aim of the CATFISH (Cumbrian Assessment of Teeth a Fluoride Intervention Study for Health) study was to address the question of whether or not the addition of fluoride to community drinking water, in a contemporary population, lead to a reduction in the number of children with caries and, if so, is this reduction cost-effective?

Design

A longitudinal prospective cohort design was used in two distinct recruited populations: (1) a birth cohort to assess systemic and topical effects of water fluoridation and (2) an older school cohort to assess the topical effects of drinking fluoridated water.

Setting

The study was conducted in Cumbria, UK. Broadly, the intervention group (i.e. individuals receiving fluoridated drinking water) were from the west of Cumbria and the control group were from the east of Cumbria.

Participants

Children who were lifetime residents of Cumbria were recruited. For the birth cohort, children were recruited at birth (2014–15), and followed until age 5 years. For the older school cohort, children were recruited at age 5 years (2013–14) and followed until the age of 11 years.

Intervention

The provision of a ‘reintroduced fluoridated water scheme’.

Main outcome measures

The primary outcome measure was the presence or absence of decay into dentine in the primary teeth (birth cohort) and permanent teeth (older school cohort). The cost per quality-adjusted life-year was also assessed.

Results

In the birth cohort (n = 1444), 17.4% of children in the intervention group had decay into dentine, compared with 21.4% of children in the control group. The evidence, after adjusting for deprivation, age and sex, with an adjusted odds ratio of 0.74 (95% confidence interval 0.56 to 0.98), suggested that water fluoridation was likely to have a modest beneficial effect. There was insufficient evidence of difference in the presence of decay in children in the older school cohort (n = 1192), with 19.1% of children in the intervention group having decay into dentine, compared with 21.9% of children in the control group (adjusted odds ratio 0.80, 95% confidence interval 0.58 to 1.09). The intervention was found to be likely to be cost-effective for both the birth cohort and the older school cohort at a willingness-to-pay threshold of £20,000 per quality-adjusted life-year. There was no significant difference in the performance of water fluoridation on caries experience across deprivation quintiles.

Conclusions

The prevalence of caries and the impact of water fluoridation was much smaller than previous studies have reported. The intervention was effective in the birth cohort group; however, the importance of the modest absolute reduction in caries (into dentine) needs to be considered against the use of other dental caries preventative measures. Longer-term follow-up will be required to fully understand the balance of benefits and potential risks (e.g. fluorosis) of water fluoridation in contemporary low-caries populations.

Limitations

The low response rates to the questionnaires reduced their value for generalisations. The observed numbers of children with decay and the postulated differences between the groups were far smaller than anticipated and, consequently, the power of the study was affected (i.e. increasing the uncertainty indicated in the confidence intervals).

Study registration

This study is registered as Integrated Research Application System 131824 and 149278.

Funding

This project was funded by the National Institute for Health and Care Research (NIHR) Public Health Research programme and will be published in full in Public Health Research; Vol. 10, No. 11. See the NIHR Journals Library website for further project information.

The Impact of Water Fluoridation on Medicaid-Eligible Children and Adolescents in Alaska

Juneau, Alaska, ceased community water fluoridation (CWF) in 2007, and previous research found a substantial increase in dental caries-related procedures and treatment costs for children from low-income families in Juneau between 2003 and 2012. We collected comparable dental caries-related procedures and treatment cost data for the same years for children in Anchorage, Alaska, where CWF has been continuously maintained. This retrospective study analyzed all Medicaid dental claims records in two separate years for caries-related procedures and associated costs among children (aged 0 to 18 years) residing in Anchorage's 99502 zip code and compared these records to data from Juneau. We obtained descriptive statistics and conducted bivariate analyses and binomial logistic regression. Between 2003 and 2012, children in Anchorage experienced a nonsignificant modest decrease in the mean number of caries-related procedures and only small, statistically nonsignificant changes to the mean inflation-adjusted service costs of caries-related restorative care. The lack of significant change in child dental caries-related procedures and treatment costs in Anchorage between 2003 and 2012 contrasted with the substantial increase in caries-related procedures and treatment costs over the same period in Juneau. Our results are consistent with previous research that has demonstrated a significant protective effect of CWF against dental caries.

Child Fluoride Varnish Programs Implementation: A Consensus Workshop and Actions to Increase Scale-Up in Australia

This paper presents the findings of the National Fluoride Varnish Workshop in 2018 along with subsequent actions to scale-up the use of fluoride varnish nationally in Australia. The use of fluoride varnish programs to prevent dental caries in high-risk child populations is an evidence-based population health approach used internationally. Such programs have not been implemented at scale nationally in Australia. A National Fluoride Varnish Consensus Workshop was held in Sydney in November 2018 with an aim of sharing the current work in this area being undertaken by various Australian jurisdictions and seeking consensus on key actions to improve the scale-up nationally. Forty-four people attended the Workshop with oral health representatives from all Australian state and territory health departments, as well as the Australian Dental Association (ADA) at both NSW branch and Federal levels. There was strong support for further scale-up of fluoride varnish programs nationally and to see the wider use of having non-dental professionals apply the varnish. This case study identifies key actions required to ensure scale-up of systematic fluoride varnish programs as part of a strategic population oral health approach to preventing dental caries among high-risk children who may not routinely access dental care.

Cost-effectiveness of caries preventive interventions - a systematic review

OBJECTIVE

The primary purpose of this study was to assess the cost-effectiveness of caries preventive interventions.

MATERIAL AND METHODS

A systematic review was conducted, following the PRISMA Statement. Four electronic databases were searched (final search 16 March 2020). Studies fulfilling the inclusion criteria were independently critically appraised, by two reviewers in parallel. Data from each included study were extracted and tabulated: the analysis used a narrative approach to present the results of the estimated cost-effectiveness.

RESULTS AND CONCLUSIONS

Twenty-six publications fulfilled the inclusion criteria and were of low or moderate risk of bias. Ten publications were economic evaluations, directly based on empirical studies, and the other 16 were modelling studies. Most of the studies concerned interventions for children and the most common were analyses of fluoride varnish and risk-based programs. Some of the studies showed both reduced cost and improved outcomes, but most studies reported that the improved outcome came with an additional cost. The results disclosed several cost-effectiveness evaluations of caries preventive interventions in the literature, but these target primarily children at high risk. There is a scarcity of studies specifically targeting adults and especially the elderly.

Association of COVID-19-imposed lockdown and online searches for toothache in Iran

BACKGROUND

Novel coronavirus disease-2019 (COVID-19) has impacted populations in many ways worldwide, including access to oral health services. This study aims to assess the association between lockdown due to COVID-19 and online searches for toothache in Iran using Google Trends (GT).

METHODS

We investigated GT online searches for toothache within the past five years. The time frame for data gathering was considered as the initiation and end dates of the national lockdown in Iran. We performed one-way ANOVA statistical test to compare relative search volumes (RSVs) between the year 2020 and 2016-2019 for the whole country. Then we investigated the possible association of RSVs in provinces with dentists' density, prevalence of current daily smokers, Human Development Index (HDI), Internet access, and fluoride concentration in water using linear regression.

RESULTS

When comparing 2020 with the previous four years, there was a rise of 2020 RSVs versus all previous years combined and each year (P < 0.001 for all of them). In the linear model for the year 2020, HDI (B = - 3.29, 95% CI: (- 5.80, - 0.78), P = 0.012) had a strong negative relationship with provincial RSVs. HDI mostly had strong positive relationship with provincial RSVs in prior years. Fluoride concentration (B = - 0.13, 95% CI: (- 0.24, - 0.03), P = 0.017) and dentists' density (B = - 0.04, 95% CI: (- 0.25, 0.17), P = 0.669) were also negatively associated with RSVs in 2020. These associations were mostly negative in the previous years as well. Internet access (B = 0.36, 95% CI: (- 0.38, 1.09), P = 0.325) and prevalence of daily smokers (B = 0.33, 95% CI: (0.13, 0.53), P = 0.002) were positively associated with RSVs.

CONCLUSION

The RSVs for toothache in 2020 have increased due to COVID-19-imposed lockdown compared with the same period in the past four years. This increase was related to socioeconomic factors.