Developing methodology for exposure assessment of air pollutants in schools

This thesis was submitted for the degree of Master of Philosophy and awarded by Brunel University.Increasing evidence suggests that exposures to air pollutants present in indoor environments are contributing factors to the recently observed increase in respiratory symptoms among young children. The SchoolAir pilot study aimed to assess the hypothesis that poor indoor and outdoor air quality in schools is associated with increased prevalence of asthma, respiratory and allergic symptoms among primary school children, and assess the feasibility of a bigger full-scale research project in the future. The main aim of this MPhil project was to develop and test a methodology for exposure assessment of indoor and outdoor pollutants in primary schools. A secondary aim was to assess the prevalence rate or respiratory symptoms and their relationship to air pollutant exposure in different schools. The following pollutants were measured indoors and outdoors: carbon monoxide (CO), carbon dioxide (CO2), nitrogen dioxide (NO2), total volatile organic compounds (TVOC) formaldehyde (HCHO), and particulate matter of 0.5–5.0 micrometers in diameter (PM0.5-5.0). A questionnaire was used to assess respiratory health effects in children. Air quality monitoring was conducted in three rounds in four primary schools in England. Real time measurements were performed simultaneously in three indoor locations and one outdoor location within each school, for one week during usual school hours. Personal exposure (PE) to each pollutant was estimated combining time-activity patterns of children and measured concentrations. Findings showed important temporal and spatial variations in concentrations of certain air components. The most prominent variability was observed for PM0.5-5.0 and CO2. Weekly means for PE to PM0.5-5.0, NO2 and TVOC were higher than concentrations measured in classrooms (ME) in the majority of cases, whereas for CO, HCHO and CO2 the opposite effect was observed. The calculated coefficients of variations for ME and PE revealed that variability of modelled PE was higher than that of relevant ME. Thus modelled PE seems to reflect more of the actual variability of exposures that children had during their days at school than exposures measured by fixed monitors in a classroom. The results of linear regression of PE to ME showed that for the three of the six investigated indoor air components – PM0.5-5.0, NO2, and CO2 – less than 50% of the variation of PE could be explained by the variation of relevant ME. For the other three pollutants – CO, HCHO and TVOC the results of linear regression were inconclusive, as half of the calculated coefficients of determinations (R2) were above 0.5 and the other half were below 0.5. Preliminary analysis of the health survey results revealed variations of respiratory and allergic symptoms prevalence between the investigated schools. It was shown that the children in one of the suburban schools, where the modelled yearly mean PEs were in the upper end of the inter-school yearly means range had the highest proportion of respiratory and allergic symptoms, whereas in the rural school the modelled yearly mean PEs were overall in the lower end of the inter-school yearly means range, and the children of the rural school had the lowest prevalence of symptoms. The methodology used in this study for the assessment of children’s personal exposure to air pollutants during a school day employed a combination of measurements by stationary monitors in school microenvironments and children’s time-activity-location patterns. This study revealed important differences between concentrations measured with fixed monitors and estimated personal exposures for all measured pollutants. This methodology is efficient and potentially less expensive than individual personal monitoring

Economics of primary caries prevention in preschool children

Background: Childhood caries continues to be a pandemic disease and a significant but preventable public health problem worldwide. Caries can have a major impact on children's health and quality of life as well as represent cost to individuals, the health sector and society. Research indicates that children who develop caries in early childhood are likely to have a high risk of the disease in adolescence and adulthood. Dental caries is a preventable disease and currently a range of nationwide programmes, community-based programmes and clinical strategies exist to reduce caries prevalence in children. Notwithstanding the fact that childhood caries is very widespread and that it poses a substantial economic burden, there is a paucity of economic evaluations of caries prevention interventions in preschoolers. The lack of high-quality economic evaluations makes it difficult for decision-makers to determine which interventions to provide within the remit of health services and local authorities. Aim: To explore the role of economic evaluation in primary caries prevention in preschool children aged 2-5 years. This aim was met through answering the following three research questions. (1) What is the existing evidence in the field of economic evaluation of primary caries prevention in children aged 2-5 years? (2) Which general health and oral health-related quality of life measures have been used in 3-5-year-old populations? And which of these measures are best suited to be used in a caries prevention randomised controlled trial for this age group? (3) Is the application of fluoride varnish delivered in nursery settings in addition to the other usual components of the Scottish child oral health improvement programme, Childsmile, (treatment as usual) cost-effective in comparison with treatment as usual only? Methods: Three interlinked empirical work segments were undertaken to address these research questions. (1) A systematic review of economic evaluations of primary caries prevention in 2-5-year-old preschool children. (2) A non-systematic review of instruments for measuring general and oral health-related quality of life in 3-5-year-old children. (3) An economic evaluation of the Protecting Teeth @ 3 randomised controlled trial (trial registration: EUDRACT: 2012-002287-26; ClinicalTrials.gov: NCT01674933). Results: (1) The systematic review of economic evaluations of primary caries prevention in 2-5-year-olds found that cost analysis and cost-effectiveness analysis were the most frequently used types of economic evaluations. Only one study employed cost-utility analysis. The systematic review highlighted wide variation in: (a) types of caries prevention interventions investigated; (b) effectiveness measures used; (c) how costs and outcomes are reported; and d) study perspective (when indicated). The parameters not reported well included study perspective, baseline year, sensitivity analysis, and discount rate. The results of the quality assessment of the full economic evaluations using the Consolidated Health Economic Evaluation Reporting Standards (CHEERS) checklist showed substantial variation in reporting quality. The CHEERS items that were most often unmet were characterizing uncertainty, study perspective, study parameters, and estimating resources and costs. (2) The review of general health and oral health-related quality of life measures identified a range of existing questionnaires for use in preschool populations (age 3-5 years) and their strengths and limitations were considered. Only two preference-based general health-related quality of life instruments that had been used in 3-5-year-olds were identified. No preference-based oral health-related quality of life measures for preschoolers were identified. Four instruments were selected to be used in the Protecting Teeth @ 3 trial: the Child Health Utility 9 Dimensions, PedsQL (Paediatric Quality of Life Inventory) Core, PedsQL Oral Health (an oral health specific add-on to PedsQL Core) and the Scale of Oral Health Outcomes for 5-year-old children. (3) The findings of the Protecting Teeth @ 3 trial economic evaluation demonstrated that there were no statistically significant differences in total costs, quality adjusted life years (QALYs) accumulated, the change in the clinical effectiveness outcome (d3mft), and in general health and oral health-related quality of life measures at 24 months between the intervention and control groups. The mean difference in total costs between the fluoride varnish (intervention) and treatment as usual (control) group was £68 (p=0.382; 95% confidence interval £18, £144). The mean difference in QALYs was -0.004 (p= 0.636; 95% confidence interval -0.016, 0.007). The probability that the fluoride varnish intervention was cost-effective at the £20,000 threshold was 11%. Conclusions: The systematic review of economic evaluations of primary caries prevention in 2-5-year-olds found that within the past two decades, there has been an increase in the number of economic evaluations of caries prevention interventions in preschool children. However, there was inconsistency in how these economic evaluations of primary caries prevention were conducted and reported. Lack of use of preference-based health-related quality-of-life measures was identified. The use of appropriate study methodologies and greater attention to recommended economic evaluations design are required to further improve quality. Due to small numbers of studies investigating each intervention type (for example, fluoride varnish, oral health education, dental sealants, toothbrushing, water fluoridation) and the questionable methodological quality of many of the reviewed economic evaluations, it was not possible to arrive at reliable conclusions with regards to the economic value of primary caries prevention. With dental caries being one of the most common diseases affecting humans worldwide, the identification of cost-effective prevention strategies in children should be a global public health priority. In order for this to be achieved, studies should be designed to include economic evaluations using best practice methods guidance and adhering to standards for reporting and presenting. The review of general health and oral health-related quality of life measures used in 3-5-year-olds identified a range of existing questionnaires for use in preschool populations – both for parental proxy reporting and child self-reporting. Four instruments were selected to be used in the Protecting Teeth @ 3 trial. Further research and development of new preference-based measures suitable for preschoolers (or their parents/guardians as a proxy) are required. The results of the economic evaluation of the Protecting Teeth @ 3 trial show that applying fluoride varnish in nursery settings in addition to the existing treatment a usual (all other components of the Childsmile programme, apart from nursery fluoride varnish) is not likely to be cost-effective. In view of previously proven clinical effectiveness and economic worthiness of the universal nursery toothbrushing component of Childsmile, which was shown to be highly cost saving, as well as being effective and cost saving in the most deprived populations, continuation of the programme of targeted nursery fluoride varnish in its most recent (pre-COVID-19) form and shape in addition to nursery toothbrushing and other routine Childsmile components needs to be reviewed in consultation with policy makers. The findings also have wider implications for other countries looking to develop their own childhood caries prevention programmes

Systematic review of economic evaluations of primary caries prevention in 2- to 5-year-old preschool children

Objectives: To describe and summarize evidence on economic evaluations (EEs) of primary caries prevention in preschool children aged 2 to 5 years and to evaluate the reporting quality of full EE studies using a quality assessment tool. Methods: A systematic literature search was conducted in several databases. Full and partial EEs were included. The reporting quality of full EE studies was assessed using the Consolidated Health Economic Evaluation Reporting Standards (CHEERS) checklist. Results: A total of 808 studies were identified, and 39 were included in the review. Most papers were published between 2000 and 2017 and originated in the United States and the United Kingdom. The most common type of intervention investigated was a complex multicomponent intervention, followed by water fluoridation. Cost analysis and cost-effectiveness analysis were the most frequently used types of EE. One study employed cost-utility analysis. The proportion of full EEs increased over time. The parameters not reported well included study perspective, baseline year, sensitivity analysis, and discount rate. The CHEERS items that were most often unmet were characterizing uncertainty, study perspective, study parameters, and estimating resources and costs. Conclusions: Within the past 2 decades, there has been an increase in the number of EEs of caries prevention interventions in preschool children. There was inconsistency in how EEs were conducted and reported. Lack of preference-based health-related quality-of-life measure utilization in the field was identified. The use of appropriate study methodologies and greater attention to recommended EE design are required to further improve quality

Fluoride varnish in nursery schools: a randomised controlled trial – Protecting Teeth @3

Studies suggest that fluoride varnish (FV) application can reduce dental caries in child populations. The multiple-component national child oral health improvement programme in Scotland (Childsmile) includes nursery-based universal supervised toothbrushing and deprivation-targeted FV applications, together with community and dental practice prevention interventions. This trial, a double-blind, two-arm randomised control trial, aimed to assess the effectiveness and cost-effectiveness of the nursery-based FV applications plus treatment-as-usual (TAU) Childsmile programme interventions, compared to TAU Childsmile interventions alone, in children not targeted to receive nursery FV as part of the programme. Participating children in the first year of nursery (aged three), with or without existing caries, were randomised to either FV or TAU and followed up for 24 months until the first year of primary school. Treatments were administered at six-monthly intervals. The primary endpoint was “worsening of d3mft” from baseline to 24 months. Secondary endpoints were worsening of d3mfs, d3t, mt, and ft. Individual record-linkage captured wider programme activities and tertiary endpoints. A total of 1,284 children were randomised, leading to 1,150 evaluable children (n = 577 FV, n = 573 TAU, 10% dropouts). Mean age was 3.5 years, 50% were female (n = 576), 17% had caries at baseline (n = 195), all balanced between the groups. Most children received three/four treatments. Overall, 26.9% (n = 155) had worsened d3mft in the FV group, and 31.6% (n = 181) in the TAU group, with an odds ratio (OR) of 0.80 (0.62–1.03), p = 0.078. The results for worsening of the secondary endpoints were: d3mfs 0.79 (0.61–1.01) p = 0.063, d3t 0.75 (0.57–0.99) p = 0.043, mt 1.34 (0.75–2.39) p = 0.319, and ft 0.77 (0.53–1.14) p = 0.191. We calculated a number needed to treat of 21 and a cost of GBP 686 to prevent a single worsening of d3mft. There was a modest non-significant reduction in the worsening of d3mft in the nursery FV group compared to TAU, suggesting that this intervention is unlikely to represent an effective or cost-effective addition to the population oral health improvement programme

Comparison of the caries-protective effect of fluoride varnish with treatment as usual in nursery school attendees receiving preventive oral health support through the Childsmile oral health improvement programme - the Protecting Teeth@3 Study:a randomised controlled trial

Background: The Scottish Government set out its policy on addressing the poor oral health of Scottish children in 2005. This led to the establishment of Childsmile, a national programme designed to improve the oral health of children in Scotland. One element of the programme promotes daily tooth brushing in all nurseries in Scotland (Childsmile Core). A second targeted component (Childsmile Nursery) offers twice-yearly application of fluoride varnish to children attending nurseries in deprived areas. Studies suggest that fluoride varnish application can reduce caries in both adult and child populations. This trial aims to explore the effectiveness and cost-effectiveness of additional preventive value fluoride varnish application compared to Childsmile Core. Methods/Design: The Protecting Teeth@3 Study is an ongoing 2 year parallel group randomised treatment as usual controlled trial. Three-year-old children attending the ante pre-school year are randomised (1:1) to the intervention arm (fluoride varnish & treatment as usual) or the control arm (treatment as usual). Children in the intervention arm will have Duraphat® fluoride varnish painted on the primary tooth surfaces and will continue to receive treatment as usual: the core Childsmile Nursery intervention. Children in the treatment as usual arm will receive the same series of contacts, without the application of varnish and will also continue with the Childsmile Core intervention. Interventions are undertaken by Childsmile trained extended duty dental nurses at six-monthly intervals. Participants receive a baseline dental inspection in nursery and an endpoint inspection in Primary 1 at the age of 5 years old. We will use primary and secondary outcome measures to compare the effectiveness of Duraphat® fluoride varnish plus treatment as usual with treatment as usual only in preventing any further dental decay. We will also undertake a full economic evaluation of the trial

Exploring the cost-effectiveness of child dental caries prevention programmes. Are we comparing apples and oranges?

No abstract available

Improving child oral health: cost analysis of a national nursery toothbrushing programme

Dental caries is one of the most common diseases of childhood. The aim of this study was to compare the cost of providing the Scotland-wide nursery toothbrushing programme with associated National Health Service (NHS) cost savings from improvements in the dental health of five-year-old children: through avoided dental extractions, fillings and potential treatments for decay. Methods: Estimated costs of the nursery toothbrushing programme in 2011/12 were requested from all Scottish Health Boards. Unit costs of a filled, extracted and decayed primary tooth were calculated using verifiable sources of information. Total costs associated with dental treatments were estimated for the period from 1999/00 to 2009/10. These costs were based on the unit costs above and using the data of the National Dental Inspection Programme and then extrapolated to the population level. Expected cost savings were calculated for each of the subsequent years in comparison with the 2001/02 dental treatment costs. Population standardised analysis of hypothetical cohorts of 1000 children per deprivation category was performed. Results: The estimated cost of the nursery toothbrushing programme in Scotland was £1,762,621 per year. The estimated cost of dental treatments in the baseline year 2001/02 was £8,766,297, while in 2009/10 it was £4,035,200. In 2002/03 the costs of dental treatments increased by £213,380 (2.4%). In the following years the costs decreased dramatically with the estimated annual savings ranging from £1,217,255 in 2003/04 (13.9% of costs in 2001/02) to £4,731,097 in 2009/10 (54.0%). Population standardised analysis by deprivation groups showed that the largest decrease in modelled costs was for the most deprived cohort of children. Conclusions: The NHS costs associated with the dental treatments for five-year-old children decreased over time. In the eighth year of the toothbrushing programme the expected savings were more than two and a half times the costs of the programme implementation

Population of 5 year old / 3–4 year old children, costs and expected savings of dental treatments per 5 year old child, and cost of nursery toothbrushing programme per 3–4 year old child, Scotland, 1999/00–2009/10 financial years.

<p>All costs / expected savings are reported in 2009 British pound sterling (GBP, £).</p><p>* Source: General Register Office for Scotland / National Records of Scotland (2000–2010), Mid-year estimated population by sex, single year of age and administrative area– 1999–2009 years. Based on the 2001 Scotland’s Census (<a href="http://www.nrscotland.gov.uk/statistics-and-data/statistics/statistics-by-theme/population/population-estimates/mid-year-population-estimates/archive" target="_blank">http://www.nrscotland.gov.uk/statistics-and-data/statistics/statistics-by-theme/population/population-estimates/mid-year-population-estimates/archive</a>); accessed 29 May 2015)</p><p>** The positive value is an additional cost per 5 year old child in the population, whereas the negative values are expected savings per 5 year old child, in comparison with the dental treatments costs in the baseline year 2001/02.</p><p>*** Our assumption was that the cost of the toothbrushing programme was constant over time. Hence there is little variation in the average cost per 3–4 year old child in the Scottish population over time.</p><p>Population of 5 year old / 3–4 year old children, costs and expected savings of dental treatments per 5 year old child, and cost of nursery toothbrushing programme per 3–4 year old child, Scotland, 1999/00–2009/10 financial years.</p

Costs of actual and anticipated dental treatments in five-year-old children (baseline scenario), cost of nursery toothbrushing programme and d₃mft over time—Scotland, by financial year.

<p>d₃mft index is the number of obviously decayed, missing (due to decay) and filled teeth per child. The “3” in the d₃mft index indicates decay into dentine.</p