Ecological influences, observational caries epidemiological trends and associated socioeconomic and geographic dental health inequalities at five-years of age in Scotland, 1993/94-2007/08

• Main Author: Blair, Yvonne Isobel
• Published: University of Glasgow 2012
• Subjects: 610.21; RK Dentistry
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.560084

Abstract: Ecological influences, observational caries epidemiological trends and associated socioeconomic and geographic dental health inequalities at five years of age in Scotland, 1993/94-2007/08 Introduction: In recent years many national Governments have called for health improvements at the population level and at the same time reductions in health inequalities. To date, dental epidemiology has concentrated mainly on tracking trends in dental health. Methodologies relating to dental health inequalities are, however, not well established. Within Scotland, over the past decade, children’s oral health improvement programmes have been established at national level. Preceding and concurrent with these developments, similar initiatives have been implemented within Greater Glasgow NHS Board. This is Scotland's largest NHS Board with the highest proportion of Scotland’s socio-economic status (SES) deprived population. Recent reports from the National Dental Inspection Programme (NDIP) for five-year-olds show improvements in dental health. The above conditions provide the opportunity to explore dental trends in more detail at geographic level within Scotland and to investigate dental health inequality methodologies within the context of health improvement programmes and overall improvements in dental health. Aim: To examine caries epidemiology data and apply and appraise a range of tests of health inequality to data from Primary 1 (P1) five-year-old children in Scotland during the period 1993/94-2007/08, against a background of health improvement programmes. Furthermore, to apply the selected inequalities tests to the caries data for a) Scotland as a whole and b) the geographic subgroups: 1] Glasgow (GGHB) and 2] the remainder of Scotland, outwith Glasgow (Not-Glasgow). Methods: Secondary analyses were performed on eight successive cross-sectional NDIP five-year-olds' caries datasets, 1993/94 to 2007/08. These permitted both SES and geographic trends in mean d3mft and % dmft=0 to be plotted for the areas: Scotland, GGHB and Not-Glasgow. The metrics selected to model dental health inequalities were: the Significant Caries Index (SIC) and modified SIC10, the Receiver Operator Curve (ROC), the Gini coefficient, the Concentration Curve (CC), Koolman and Doorslaer's transformed Concentration Index (CI), the Slope Index of Inequality (SII), the Relative Index of Inequality (RII) and the Population Attributable Risk (PAR). Odds Ratios and Meta-analyses using Generalised Linear Modelling assessed statistical-inference for dental health and inequality trends. Results: Overall, usable data was retrieved for 68,398 five-year-old subjects (n=18,174 from GGHB; n=50,224 from Not-Glasgow). In Scotland as a whole, marked SES gradients in caries prevalence and caries burden were related to the DepCat score of children’s home postcode. Between the start and endpoints of the study, the simple absolute SES inequality in mean d3mft between the most affluent and most deprived groups decreased (p<0.02), whilst mean d3mft reduced across the entire SES spectrum. Relative to the baseline year (1993), by 2007, the Odds Ratios for d3mft>0 in Scotland decreased (p<0.0001) to 0.43 (95%CI, 0.40-0.46). Although Scotland's simple absolute SES related dental health inequality (DHI) decreased for mean d3mft (p<0.02), there were no improvements in simple relative SES DHIs over this time period. Simple absolute and simple relative geographic inequalities in weighted %d3mft=0 and mean d3mft were seen when GGHB was compared with Not-Glasgow data. These geographic inequalities metrics tended to increase from 1993/94 until 1999/00. However, by 2007/08 reductions in simple absolute geographic inequality were observed, with marginal improvements in simple relative geographic inequality compared to baseline. Additionally, simple absolute and relative geographic inequality in SIC scores decreased overall against a background of SIC improvements in both GGHB & Not-Glasgow (Meta-analysis, p<0.01, respectively). By 2007/08, relative to 1993/94, Odds Ratios for d3mft>0 in the geographic subgroups GGHB and Not-Glasgow decreased, respectively (p<0.0001), to 0.31 (95%CI, 0.26-0.38) and 0.46 (95%CI, 0.43-0.50). There was evidence of a 'Glasgow (dental health) Effect', whereby GGHB children’s dental health was poorer than in Not-Glasgow during the period 1993 to 1999, after controlling for confounding factors (p<0.01). This ‘Glasgow Effect’ was no longer evident by 2007. Modelling caries data using the complex inequality metrics has given further insights into different dimensions of geographic and SES-related dental health inequalities. For example, in each area from 1993/94-2007/08, the full SIC10 distributions showed respective decreases in complex absolute DHI in affected individuals in population deciles (irrespective of SES). Simultaneously, Scotland's SII indicated that complex absolute SES inequalities decreased (p<0.02). Furthermore, in Glasgow the %PAR decreased by 24 percentage points, itself impacting on Scotland's decreased PAR. However, the RII and transformed CI indicated that complex relative SES DHI increased in each area over the period of study. The ROC, CC & RII plots were comparatively stable over time for Scotland, compared to trends in the GGHB subgroup. There was evidence of some variation in DHI, and the Gini-coefficient (for individual DHI) was counter-intuitive. Discussion: Analysis and interpretation of simple and complex absolute and relative DHI outcomes are not straightforward against a background of population dental health improvements across the SES spectrum. If equivalent absolute dental health improvements are achieved in the best and poorest d3mft groups, as %d3mft>0 and mean d3mft diminish in the denominator group it is increasingly difficult to achieve improvement in relative inequalities. Nonetheless, tests suggest that simple absolute geographic DHI in Scotland's P1's weighted %d3mft=0 and mean d3mft have improved, while simple relative geographic inequality has not deteriorated over the interval 1993-2007. Further insights were obtained from examination of the cross-sectional distributions of SIC10. These showed improvements in complex absolute individual inequality across all population deciles with d3mft>0, over time, at each geographic level. Moreover, comparison of the geographic SIC10 scores for the worst affected deciles demonstrated reductions in simple absolute and relative geographic DHI in five-year-olds' d3mft morbidity for those with the poorest dental health outcomes in 2007 vs. 1993. Furthermore, Scotland's complex absolute SES-related DHI has decreased over time when assessed by SII. Improvements in complex absolute SES-related DHI have occurred more readily than improvements in complex relative SES-related DHI. Conclusions: For the first time, these multiple tests of inequality have been applied to Scotland’s and Glasgow’s child caries datasets. Generally, caries epidemiology trends occurred slowly and smoothly, however, DHI trends from this same data tended to fluctuate (especially in the geographic subgroups). The apparent lack of consonance of the various inequalities metrics demonstrates that measurement, understanding and interpretation of population DHI trends are complicated and require knowledge of the underlying epidemiology trends. Nonetheless, with the exception of the Gini, all results provided useful information which aid understanding of DHI. The complex measures such as the SII and RII had the advantage of using all the available d3mft information within the DepCat domains and weighting results for SES within the denominator populations. Furthermore, in Scotland as a whole, the SIC10 distribution, SII and RII appear to exhibit stable DHI trends, against the background populations' dental health improvements.