Final Project Milestone Two: Literature Review

Socioeconomic Status, Food Security, and Dental Caries in US Children: Mediation Analyses of Data From the National Health and Nutrition Examination Survey, 2007–2008 Donald L. Chi, DDS, PhD, Erin E. Masterson, MPH, Adam C. Carle, PhD, Lloyd A. Mancl, PhD, and Susan E. Coldwell, PhD Tooth decay (dental caries) is the most preva- lent disease worldwide and the most common pediatric disease in the United States. 1, 2 From 1999 to 2004, the prevalence of untreated tooth decay was 24.5% for children aged 6 to 11 years and 19.6% for adolescents aged 12 to 19 years. 3Untreated tooth decay can lead to difﬁculties eating and sleeping, pain, the need for invasive restorative treatment, emergency department visits and inpatient hospitaliza- tions, poor quality of life, systemic health problems, and, in rare cases, death. 4---7 To date, most public health efforts aimed at addressing the pediatric caries epidemic have focused on tooth-level interventions (e.g., topicalﬂuorides, dental sealants). Although disparities in oral health are considered a measure of social injustice, 8comparatively less research has been conducted on the social determinants of pedi- atric oral health. 9 Low socioeconomic status (SES), one of the strongest determinants of caries in children, 10 ---12 is associated with food insecurity, 10 ---17 deﬁned as inadequate access to food resulting in food shortages, disrupted eating patterns, and hunger. 18Food insecurity, in turn, is associ- ated with oral health---related behaviors, in- cluding increased fermentable carbohydrate intake, 19,20 a risk factor for dental caries. 21,22 The American Dietetic Association recognizes the link between nutrition and oral health, 23 and numerous studies have drawn associations between dietary factors and disparities in den- tal caries. 24 Collectively, these studies suggest that food insecurity is related to caries and is a potential mechanism linking SES and caries, but these relationships have not yet been evaluated empirically. We used nationally representative data from the United States to test 3 hypotheses: (1) food insecurity is positively associated with untreated dental caries, (2) food insecurity mediates theSES---caries relationship, and (3) food insecurity mediates the SES---caries relationship differen- tially for children from higher- versus lower- SES households. METHODS We conducted a cross-sectional analysis of US National Health and Nutrition Examination Survey (NHANES) data from 2007 and 2008.

NHANES collects interview and physical ex- amination data from about 5000 nationally representative children and adults each year. 25 The 2007 to 2008 NHANES data set includes clinical caries data collected from participants aged 5 years and older. Trained and calibrated oral health examiners screened each child. No dental history or radiographs were taken. The survey collected aggregate data on whether the child had any untreated caries (no or yes). As part of the NHANES oral health protocol, stains, white spots, pitted enamel, and erosion were not classiﬁed as untreated caries. The child’s primary caregiver or legal guardiancompleted a questionnaire that produced demographic, food insecurity, and other self- reported data. Our analyses focused on chil- dren aged 5 to 17 years (n = 2206). Conceptual Model and Variables A preliminary conceptual model is pre- sented in Figure 1. 10 --- 2 3 The outcome mea- sure was any untreateddentalcaries(noor yes). Untreated dental caries is a binary vari- able in the 2007 to 2008 NHANES data set, which precluded an analysis of caries as a continuous variable. We chose untreated caries because it measures disease prevalence atthesametimeasourpredictorvariableand mediator were measured. Adopting alterna- tive prevalence measures (e.g., untreated caries +ﬁllings or restorations) would in- troduce temporality problems. The predictor variable was SES, operationalized as the ratio of household income to poverty, a measure used in previous analyses involving SES. 26 Larger income-to-poverty ratios indicated higher SES. Objectives.We examined associations of household socioeconomic status (SES) and food security with children’s oral health outcomes.

Methods.We analyzed 2007 and 2008 US National Health and Nutrition Examination Survey data for children aged 5 to 17 years (n = 2206) to examine the relationship between food security and untreated dental caries and to assess whether food security mediates the SES–caries relationship.

Results.About 20.1% of children had untreated caries. Most households had full food security (62%); 13% had marginal, 17% had low, and 8% had very low food security. Higher SES was associated with signi cantly lower caries prevalence (prevalence ratio [PR] = 0.77; 95% con dence interval = 0.63, 0.94; P= .01). Children from households with low or very low food security had signi cantly higher caries prevalence (PR = 2.00 and PR = 1.70, respectively) than did children living in fully food-secure households. Caries prevalence did not differ among children from fully and marginally food-secure households (P= .17). Food insecurity did not appear to mediate the SES–caries relationship.

Conclusions.Interventions and policies to ensure food security may help address the US pediatric caries epidemic. (Am J Public Health.2014;104:860–864.

doi:10.2105/AJPH.2013.301699) RESEARCH AND PRACTICE 860|Research and Practice|Peer Reviewed|Chi et al.American Journal of Public Health|May 2014, Vol 104, No. 5 The potential mediator was household-level food security (full, marginal, low, or very low food security), measured with the US Depart- ment of Agriculture 18-item Household Food Security Survey. 27 We classiﬁed respondents with no afﬁrmative responses to any survey items as living in households with full food security. We classiﬁed those with 1 to 2 afﬁrmative responses as having marginal, 3 to 7afﬁrmative responses as having low, and 8 or more afﬁrmative responses as having very low food security. 28 Statistical Analyses We used log-linear regression models to examine the SES---caries (model 1) and food insecurity---caries (model 2) relationships and to estimate prevalence ratios (PRs). 29,30 In model 3, we used standard mediation methods to examine the relationship between SES and caries after including food insecurity in model 1. 31We ran similar mediation models stratiﬁed on SES (split at the median SES) to identify a potential interaction between SES and food insecurity and age-adjusted models to adjust for age as a potential model confounder.

Becauseﬁndings from the SES-stratiﬁed and age-adjusted models were consistent with results from the initial regression models, we only reported the latterﬁndings. We used jackknife methods to estimate standard er- rors 29 and accounted for the complex survey design with Stata version 12.1 (StataCorp LP, College Station, TX). RESULTS The mean household size was 4.7 (SD = 1.4; Table 1). Thirty-eight percent of children were Hispanic, 31% were White, and 26% wereBlack. Forty-three percent were privately in- sured, 26% were enrolled in Medicaid, 17% had other health insurance, and 14% were uninsured. Forty-three percent of children were in excellent health, 50% in very good or good health, 6% in fair health, and 1% in poor health. About 20.1% of children had untreated caries. The mean household income---to---poverty ratio was 2.1 (SD = 1.5).

Most children lived in households with full food security (62%); 13% lived in households with marginal, 17% with low, and 8% with very low food security.

We detected a signiﬁcant SES---caries rela- tionship (Table 2). Higher SES was associated with lower untreated caries prevalence (PR = 0.77; 95% conﬁdence interval CI = 0.63, 0.94;P= .01). Children from low or very low food security households had signiﬁcantly higher untreated caries prevalence (PR = 2.00 and PR = 1.70, respectively) than children with full food security. We observed no difference in untreated caries between children from fully and marginally food-secure households (P= .17). Results from models 1 and 3 in- dicated that food insecurity did not partially or fully mediate SES and untreated caries. These ﬁndings were similar in the SES-stratiﬁed and age-adjusted models (data not shown). DISCUSSION Ours was theﬁrst published study, to our knowledge, that examined the relationship between food insecurity and untreated dental caries in children. Our analyses of nationally representative data from the United States for children aged 5 to 17 years revealed a signiﬁcant relationship between food insecu- rity and untreated dental caries. Children livingin households with low and very low food security had a greater prevalence of untreated caries than children from fully food-secure households. In addition, food insecurity did not appear to mediate the SES---caries relationship, aﬁnding that was consistent for children from higher- and lower-SES households.

Our mainﬁnding was that food insecurity was signiﬁcantly associated with dental caries.

Thisﬁnding is consistent with published studies demonstrating negative health outcomes associ- ated with food insecurity. 32---37 We believe there are 4 potential explanations. First, food insecurity may force caregivers and children to make food-purchasing decisions that optimize for Socioeconomic Status Food Insecurity Diet Dental Caries Topical Fluoride Dental Care Use Note.Gray boxes and arrows indicate portions of model not tested.

FIGURE 1—Preliminary conceptual model of relationship between socioeconomic status, food insecurity, and dental caries: National Health and Nutrition Examination Survey, United States, 2007–2008. TABLE 1—Household and Child Characteristics of Children Aged 5–17 Years: National Health and Nutrition Examination Survey, United States, 2007–2008 Characteristic No. (%) or Mean6SD Head of household education level < grade 9 242 (11) Grade 9–11 416 (19) High school or GED 523 (24) Some college 589 (27) ‡college 361 (16) Missing 75 (3) Persons in household 4.761.4 Child race/ethnicity Mexican American 563 (25) Other Hispanic 278 (13) Non-Hispanic White 689 (31) Non-Hispanic Black 575 (26) Other/multiracial 101 (5) Child health insurance Private 952 (43) Medicaid only 575 (26) Other 374 (17) None 297 (14) Missing 8 (< 1) Child health condition Excellent 959 (43) Very good 574 (26) Good 528 (24) Fair 125 (6) Poor 20 (1) Note. GED = general equivalency diploma. Sample size was n = 2206. RESEARCH AND PRACTICE May 2014, Vol 104, No. 5|American Journal of Public HealthChi et al.|Peer Reviewed|Research and Practice|861 quantity rather than quality. 38---41 For example, sugar-sweetened beverages (e.g., Tang, Hawaiian Punch, Kool-Aid) are inexpensive and easily accessible. But these unhealthy drinks contain high-fructose corn syrup or some combination of sugar, sucrose, and fructose, which are risk factors for dental caries. 22Second, food-insecure households may live in food deserts, or neigh- borhoods where purchasing options are limited to convenience stores, corner markets, and fast-food restaurants. 42These places limit purchasing op- tions to processed foods, snacks, and sugar- sweetened beverages and can deprive children of fresh vegetables and fruits, complex carbohy- drates, nonprocessed proteins, and dairy prod- ucts. Third, children living in food-insecure households may take responsibility for managing food resources, 43for example, by eating smaller amounts more frequently to make food last longer. Constant exposure to carbohydrates can lead to increased caries risk. Fourth, food in- security may be a proxy for other markers of social inequality and deprivation, including low social capital and biological stress, 44,45 both of which are associated with caries in children. 46,47 Future work should examine possible mechanisms linking food insecurity and dental caries. The knowledge generated from such studies could be used to develop mechanism-speciﬁc interventions aimed atimproving the oral health of children living in food-insecure households.

Our secondaryﬁndings were that food in- security did not mediate the SES---caries re- lationship and that this relationship did not differ among children from lower- and higher-SES households. Although several pub- lications suggest links between SES, food in- security, and child health outcomes, 48---50 our ﬁndings suggest that other social factors asso- ciated with SES (e.g., food environment) 51and behaviors (e.g., exposure toﬂuoride, visits to the dentist, speciﬁc types of nutrients and food intake) 52 may be more plausible mediators.

That food insecurity failed to mediate SES--- caries differentially for lower- and higher-SES households was surprising but points to the complexity of these relationships. Our prelimi- nary conceptual model suggested that behavioral factors might mediate the food insecurity---caries relationship while simultaneously moderating other relevant behavioral factors (Figure 1). It was not possible to test all the pathways from our model. Future studies could use this model as a guide to shed additional light on how house- hold SES, food insecurity, and other social de- terminants of health inﬂuence behaviors relevant in children’soralhealth.

The main study strength was the use of nationally representative data to test hypotheseswith clinical and policy signiﬁcance. Our study was aﬁrst step in developing nutrition-focused interventions aimed at improving oral health outcomes for children living in socioeconomi- cally vulnerable households. The policy signiﬁ- cance was that US food programs such as the Supplemental Nutrition Assistance Program and the Special Supplemental Nutrition Pro- gram for Women, Infants, and Children could strengthen implementation of evidence-based education and outreach that help households make better food choices. 53---57 These pro- grams could subsidize the purchase of fresh vegetables, fruits, meats, and dairy 58 and im- plement wireless terminals at farmers’mar- kets, 59,60 which would improve households’ access to healthier foods. Another policy solu- tion is limiting purchases funded by these programs of unhealthy items (e.g., sugar- sweetened beverages) linked to adverse health outcomes and chronic conditions (e.g., dental caries, obesity, diabetes). 58,61,62 How- ever, ethical considerations associated with restrictive approaches need to be weighed in relation to the health beneﬁts. 63 The rele- vance of these issues to children’soral health is open to further scientiﬁc inquiry through observational and experimental study designs. Limitations The analyses were cross-sectional, and all ﬁndings were associations, which do not imply causation. Food security was measured once, making it difﬁcult to assess whether it was transient or persistent. 64 Our outcome mea- sure, untreated dental caries, was a measure of disease prevalence at a single time. Some children who recently received dental restora- tions could have been misclassiﬁed as not having caries, but this likely would not have affected many children because of the rela- tively low proportion of children who get their teeth restored. 65 These limitations could be addressed through longitudinal study designs.

Our outcome was dichotomous and mea- sured at the tooth level, which did not provide data on caries severity. In addition, the data did not specify whether caries affected primary or permanent teeth. These are limitations of 2007 and 2008 NHANES data and could be addressed with prospective studies that adopt detailed dental caries measurement protocols TABLE 2—Log-Linear Regression Model of the Relationship Between Food Security and Untreated Dental Caries in Children and Food Security as a Mediator of Socioeconomic Status and Untreated Dental Caries: National Health and Nutrition Examination Survey, United States, 2007–2008 Variable Untreated Dental Caries, PR (95% CI)P Model 1: socioeconomic status a 0.77 (0.63, 0.94) .01 Model 2 Full food security (Ref) 1.00 Marginal food security 1.42 (0.85, 2.38) .17 Low food security 2.00 (1.09, 3.65) .03 Very low food security 1.70 (1.00, 2.90) .049 Model 3 Socioeconomic status a 0.79 (0.64, 0.97) .03 Full food security (Ref) 1.00 Marginal food security 1.07 (0.66, 1.75) .77 Low food security 1.42 (0.85, 2.38) .17 Very low food security 1.12 (0.60, 2.12) .7 Note. CI = con dence interval; PR = prevalence ratio. aOperationalized as the ratio of household income to poverty. RESEARCH AND PRACTICE 862|Research and Practice|Peer Reviewed|Chi et al.American Journal of Public Health|May 2014, Vol 104, No. 5 or secondary data that include tooth surface--- speciﬁc caries measures.

SES and food insecurity were self-reported measures. We measured food security with a validated instrument, but future work could validate household-level income to ensure measure accuracy. Our models did not include other potential mediators and moderators from our conceptual model (e.g., diet,ﬂuoride, dental visits). Additional studies are needed to fully test and reﬁne our preliminary con- ceptual model.

Conclusions Public health efforts to address food insecu- rity alone within vulnerable populations are unlikely to solve children’s oral health dispar- ities. Identifying potential mediators of food insecurity and caries (e.g., fast foods, sugar- sweetened beverages, micronutrients) may al- low us to develop speciﬁc nutrition-focused social and behavioral interventions for vulner- able populations. Future approaches will in- volve improving the food environment, quality, and choice for low-income communities; edu- cating socioeconomically vulnerable house- holds on healthy meal and snack preparation; and helping individuals to reduce their fre- quency of carbohydrate intake. Such inter- ventions can be strengthened by reinforcing preventive oral health behaviors (e.g.,ﬂuoride use, dental visits) and are likely to reduce the prevalence of other nutrition-mediated sys- temic conditions such as obesity, diabetes, and cardiovascular diseases. j About the AuthorsDonald L. Chi, Erin E. Masterson, Lloyd A. Mancl, and Susan E. Coldwell are with the Department of Oral Health Sciences, School of Dentistry, University of Washington, Seattle. Adam C. Carle is with the Department of Pediatrics, School of Medicine, and the Department of Psychology, College of Arts and Sciences, University of Cincinnati, Cincinnati, OH.

Correspondence should be sent to Donald L. Chi, University of Washington, School of Dentistry, Department of Oral Health Sciences, Box 357475, Seattle, WA 98195-7475 (e-mail: [email protected]). Reprints can be ordered at http://www.ajph.org by clicking the“Reprints” button.

This article was accepted September 19, 2013.

ContributorsD. L. Chi conceptualized the study, synthesized the analysis plan, helped interpret theﬁndings, and led the writing of the article. E. E. Masterson managed the data set and helped analyze the data. A. C. Carle helpedanalyze the data and interpret the results. L. A. Mancl helped synthesize the analysis plan. S. E. Coldwell helped conceptualize the study. All authors helped write the article. AcknowledgmentsThis study was supported by the National Institute of Dental and Craniofacial Research (grants K08DE020856, L60MD003921, T90DE021884, and U54DE019346.) and the William T. Grant Foundation Scholars Program.

Human Participant ProtectionThis study was exempted from protocol approval by the University of Washington institutional review board because the data were publicly available.

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