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The relationship between caregiver functional oral health literacy and child oral health status
Patient Education and Counseling 94 (2014) 411–416
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Patient Education and Counseling journal homepage: www.elsevier.com/locate/pateducou
Health Literacy
The relationship between caregiver functional oral health literacy and child oral health status Susan M. Bridges a, Divya S. Parthasarathy a, Hai Ming Wong b, Cynthia K.Y. Yiu b, Terry K. Au d, Colman P.J. McGrath c,* a Centre for the Enhancement of Teaching and Learning/Faculty of Education, The University of Hong Kong, Pokfulam, Hong Kong Special Administrative Region b Paediatric Dentistry & Orthodontics, Faculty of Dentistry, The University of Hong Kong, Hong Kong Special Administrative Region c Periodontology & Dental Public Health, Faculty of Dentistry, The University of Hong Kong, Hong Kong Special Administrative Region d Department of Psychology, The University of Hong Kong, Hong Kong Special Administrative Region
A R T I C L E I N F O
A B S T R A C T
Article history: Received 29 April 2013 Received in revised form 30 September 2013 Accepted 26 October 2013
Objective: To describe the relationship between caregivers’ oral health literacy (OHL) and the oral health status of their children in an Asian population. Methods: A random sample of 301 child/caregiver dyads was recruited from kindergartens in Hong Kong. Two locally-developed and validated OHL assessment tasks were administered to caregivers with Hong Kong Rapid Estimate of Adult Literacy in Dentistry-30 (HKREALD-30) assessing word recognition and Hong Kong Oral Health Literacy Assessment Task for Paediatric Dentistry (HKOHLAT-P) assessing comprehension. Their children’s oral health status was assessed [dental caries experience – decayed, missing, filled teeth index – (dmft) and oral hygiene status – Visible Plaque Index (VPI)]. Results: Caregivers’ literacy was associated with children’s oral health status. The HKOHLAT-P had a stronger association with children’s oral health than HKREALD-30. HKOHLAT-P and HKREALD-30 remained associated with dmft in the adjusted negative binomial regression models (accounting for socio-demographics), Incidence Rate Ratio (IRR) 0.97, p = 0.02, and 0.96, p = 0.03, respectively. In the adjusted model, HKOHLAT-P was associated with VPI (IRR 0.90, p < 0.05), but no association between HKREALD-30 and VPI was evident. Conclusion: The main conclusion of this study was that caregiver oral health literacy was associated with their child’s oral health status. A comprehension instrument had a more robust association with children’s oral status than a word recognition instrument. Practice implications: This study has implications for general public health education for designing community-level interventions. ß 2013 Elsevier Ireland Ltd. All rights reserved.
Keywords: Caregiver Oral health literacy Oral health status Child
1. Introduction Debates regarding the conceptualization and definition of health literacy (HL) [1–3] and, more recently, oral health literacy (OHL) [4,5] indicate that the fields continue to be of considerable interest. Nutbeam’s [6,7] notions of health literacy as an outcome of health promotion and as a ‘clinical risk’ or ‘personal asset’ provide a useful conceptual framing. His earlier work [3],
* Corresponding author at: Dental Public Health, Faculty of Dentistry, 3/F Prince Philip Dental Hospital, 34 Hospital Road, Hong Kong Special Administrative Region. Tel.: +852 2859 0513. E-mail addresses: [email protected] (S.M. Bridges), [email protected] (D.S. Parthasarathy), [email protected] (H.M. Wong), [email protected] (Cynthia K.Y. Yiu), [email protected] (T.K. Au), [email protected], [email protected] (Colman P.J. McGrath). 0738-3991/$ – see front matter ß 2013 Elsevier Ireland Ltd. All rights reserved. http://dx.doi.org/10.1016/j.pec.2013.10.018
making the important 3-way distinction between: (i) basic functional literacy; (ii) communicative/interactive literacy; and (iii) critical health literacy articulated some of the aspects of health literacy that are distinguishing the field from mainstream literacy research [8]. The initial and, to date, dominant focus on functional levels of (oral) health literacy is reflected in the definitions in Table 1a. OHL studies adopting a functional focus have yielded fruitful results regarding the readability of health materials [9] and the assessment of patient reading skills, including word recognition [10,11] and comprehension [12]. As a more recent evolution from the HL agenda, particularly in the USA [13–16], OHL is proving to be developing as a distinct field. These distinctions are driven by differences in healthcare contexts which are not only disciplinary in nature (see Table 1a) but also encompass unique, topic-specific communicative events and epidemiological concerns.
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Table 1a Definitions of HL and OHL. Health literacy (1998) [3]
Oral health literacy (2000) [5]
‘‘the cognitive and social skills which determine the motivation and ability of individuals to gain access to, understand and use information in ways which promote and maintain good health’’
‘‘the degree to which individuals have the capacity to obtain, process, and understand basic oral and craniofacial health information and services needed to make appropriate health decisions’’
In the paediatric context, there is substantial evidence in the medical literature indicating significant associations between caregiver’s generic health literacy levels across a range of child health status conditions [17]. However, there is limited information on the relationship between caregiver’s OHL and children’s oral health status [18,19], such as dental caries – one of the most common health problems of childhood [20]. While it is acknowledged that caregivers play a critical role in the prevention and management of children’s oral health status [21], there has been little consideration of the effect of caregiver OHL on children’s oral health. For the most part, oral health studies have focused on associations between caregivers’ OHL and subjective assessments of oral health [22–24]. As a relatively new field arising in western medicine, these studies have been conducted mostly in English dominant countries such as North America [10,11,18,19,22–27], Australia [28,29], Canada [30]. Whilst multilingualism is arising as an area of communication research in oral health [31], studies of OHL in other languages and countries remains in its infancy. There is, however, some pioneer work in SE Asia in establishing validated literacy assessment instruments both using English language India [32] and Asian languages, e.g. Cantonese [33,34]. It is yet to be fully established how OHL can inform our understandings of child oral health status and management in non-English speaking contexts, specifically amongst Chinese linguistic groups. Of these, those who speak the Cantonese dialect and read traditional Chinese script constitute a significant global population in terms of numbers and distribution [35] and, therefore, warrants separate investigation. This study, therefore, aimed to describe the relationship between the functional OHL levels of primary caregivers in a Cantonese population and the clinical oral health status of their preschool children. In addition, the study sought to determine if a complex comprehension literacy instrument had a more robust association with children’s oral health than a simple word recognition test. 2. Methods
were randomly selected to participate. Children were chosen randomly using simple random tables. Their parents were contacted through the kindergartens with an explanation of the objectives of the project and written consent was obtained. Participation was voluntary and no additional efforts were made to enrol the subjects. Eligibility criteria included healthy children who were 5 years of age and were accompanied by the primary caregiver. Children with specific learning disabilities, students requiring learning support, and caregivers who could not read and write Cantonese were excluded from the study. The flow diagram summarizing study recruitment procedures and final participation is shown in Fig. 1. 2.2. Data collection On arrival dyads were assigned identifiers and caregivers underwent literacy assessment while their children underwent clinical examinations; assessments were conducted simultaneously (and blind), so the assessors did not know about the outcomes of the assessment running in parallel. Initial administration of a word-recognition instrument, Hong Kong Rapid Estimate of Adult Literacy in Dentistry-30 (HKREALD-30) [33] to caregivers was conducted as an interview process (administration time: 2 min) by trained calibrated examiners, immediately followed by a comprehension literacy assessment, Hong Kong Oral Health Literacy Assessment Task for Paediatric Dentistry (HKOHLAT-P) [34] which was a ‘‘paper-and-pencil’’ task (administration time: 40 min). It also asked the participants to provide additional background questions on family socio-demographics and caregivers’ self-reported reading habits (administration time: 5 min). Children’s oral health status was assessed by trained and calibrated examiners, using two assessment methods. Dental caries experience was assessed using the methods and criteria as prescribed by the WHO basic oral health survey protocol whereby the number of decayed, missing and filled teeth (dmft) are counted [36]. For the age group in this study, the possible range was 0–20. Additionally, the oral hygiene status of the children was assessed
2.1. Sample This study was approved by the by the Institutional Review Board of the University of Hong Kong/Hospital Authority Hong Kong West Cluster (HKU/HA HKW IRB) (Ref: UW 09-184). A random sample of child/parent dyads were recruited from kindergartens in Hong Kong. The children were 5 years of age (birth dates ranging from December 2004 to December 2005). The sampling frame was comprised of kindergartens on Hong Kong Island with an enrollment of 70 children or more. Using SAS software version 9.3 (SAS institute Inc., Cary, NC, USA) sample power calculation based on Fisher’s Z Test for Pearson Correlation, to have a 90% chance with two-sided test at a 5% significant level for detecting at least a 0.2 correlation identified that 258 subjects would be required. To account for potential non-response of 15%, the aim was to recruit 316 child/parent dyads. One in four kindergartens was selected from Hong Kong Island (40 kindergartens in the sample frame) and a total of ten kindergartens participated. Within each kindergarten, children
Total no of dyads completed the study=301 dyads
Total no of schools selected to participate =10
Total no of participants=316 dyads
Total no of dyads failed to complete the study=15 dyads Fig. 1. Flow diagram of participants enrolled in the study.
S.M. Bridges et al. / Patient Education and Counseling 94 (2014) 411–416 Table 1b Profile of the study population (caregivers and children) (n = 301 dyads).
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2.3. Data analyses
Caregiver and child characteristics
n
%
Caregiver characteristics Gender Mother Father/other caregiver
223 78
74.1 25.9
Educational level Secondary school or lower Above secondary school
155 146
51.5 48.5
Age <40 years 40 years
192 109
63.8 36.2
Income level*
102 199
33.9 66.1
Child characteristics Gender Male Female
134 167
44.5 55.5
*20,000 HKD = 2580 USD.
using the Visible Plaque Index (VPI) [37] which provides a summary score of oral hygiene by recording plaque depositions for various sites around the tooth. VPI is the number of sites with dental plaque divided by number of sites examined and multiplied by 100.
The data analyses was carried out using SPSS statistical software. Descriptive statistics were produced to examine the profile of the study group. Bivariate analyses examined variations in oral health status (dmft and VPI). Correlation analysis (Spearman’s correlation) between the two literacy instruments was conducted. Negative binomial regression models were constructed separately for two key outcome variables – dmft and VPI. As the OHL measures showed evidence of multicollinearity, separate models for with HKREALD-30 and HKOHLAT-P as independent variables were developed. Both unadjusted and adjusted (accounting for socio-demographics and oral health literacy) models were produced.
3. Results Among the 316 dyads recruited, 301 completed all assessments; the completion rate was 95.6%. The socio-demographic profile of the study participants is presented in Table 1b. Three quarters of the children (75.4%, 227) had a dental caries experience (dmft > 0) and the mean dmft was 4.2 (SD 4.5), Table 2. Most of the dental caries experience was related to untreated dental decay: the prevalence of decayed teeth (dt) was 68.8% (207) and the mean dt was 3.3 (SD 3.9). Almost all children had evidence of plaque deposition at one or more sites (99.3%, 299) and the mean VPI was 63.5 (SD 20.4).
Table 2 Clinical oral health status of children: dental caries experience (dmft) and oral hygiene status (VPI) (n = 301 dyads). Clinical oral health status
%
n
Dental caries experience dmft Decayed teeth (dt) Missing teeth (mt) Filled teeth (ft)
75.4 68.8 30.2 7.6
227a 207a 91a 23a
4.2 3.3 0.7 0.2
4.5 3.9 1.3 0.9
0.0 0.0 0.0 0.0
Oral hygiene status VPI
99.3
299b
63.5
20.4
0.0
a b
Mean
SD
Minimum
Maximum 20.0 18.0 6.0 9.0
100
dmft > 0. VPI > 0.
Table 3 Bivariate variations in child’s clinical oral health status with respect to caregiver’s socio-demographic factors. Caregiver and child characteristics
dmft
VPI
Mean (SD)
p-Value
Caregiver characteristics Gender Mother Father/other caregiver
Mean (SD)
p-Value
4.30 (4.46) 4.14 (4.82)
0.80
63.54 (20.71) 63.47 (19.94)
0.98
## Education level Secondary school or lower Above secondary school
5.76 (5.09) 2.66 (3.21)
<0.001
66.38 (19.12) 64.66 (19.77)
0.01
# Age <40 years 40 years
4.67 (4.72) 3.53 (4.14)
0.03
63.13 (20.07) 62.25 (20.68)
0.66
Income level
5.99 (5.18) 3.37 (3.91)
<0.001
66.00 (19.96) 62.25 (20.68)
0.13
# Child characteristics Gender Male Female
4.90 (4.65) 3.75 (4.41)
0.03
65.09 (18.50) 62.26 (21.92)
0.23
##
# ##
p < 0.05. p < 0.001
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Table 4 Findings of negative binomial regression analysis. Variables
Unadjusted model IRR (95% CI, lower–upper)
Variables p-Value
Caries model Model 1.1 ### HKREALD-30
0.92 (0.90–0.96)
<0.001
Model 1.2 HKOHLAT-P
0.95 (0.93–0.97)
<0.001
###
VPI model Model 1.1 HKREALD-30
##
Model 1.2 # HKOHLAT-P
0.98 (0.97–0.99)
0.88 (0.81–0.97)
Adjusted model IRR (95% CI, lower–upper)
p-Value
Caries model Model 2.1 ## Education ## HKREALD-30
1.73 (1.26–2.38) 0.96 (0.92–0.99)
0.001 0.030
Model 2.2 ## Education # HKOHLAT-P
1.73 (1.26–2.38) 0.97 (0.94–0.99)
0.001 0.022
0.007
VPI model Model 2.1 ### Constant
15.33 (11.70–20.10)
0.010
Model 2.2 # HKOHLAT-P
0.90 (0.82–0.99)
<0.001
0.034
Caries model: Model 1.1: Unadjusted model: Dependent variable – (dmft), Independent variables – HKREALD-30. Model 1.2: Unadjusted model: Dependent variable – (dmft), Independent variables – HKOHLAT-P. Model 2.1: Adjusted model: Dependent variable – (dmft), Independent variables – gender, age, income level and education level of caregiver, gender of child, HKREALD-30. Model 2.2: Adjusted model: Dependent variable – (dmft), Independent variables – gender, age, income level and education level of caregiver, gender of child, HKOHLAT-P. VPI model: Model Model Model Model # ##
1.1: Unadjusted model: Dependent variable – (VPI), Independent variables – HKREALD-30. 1.2: Unadjusted model: Dependent variable – (VPI), Independent variables – HKOHLAT-P. 2.1: Adjusted model: Dependent variable – (VPI), Independent variables – gender, age, income level and education level of caregiver, gender of child, HKREALD-30. 2.2: Adjusted model: Dependent variable – (VPI), Independent variables – gender, age, income level and education level of caregiver, gender of child, HKOHLAT-P.
p < 0.05. p < 0.01. p < 0.001.
###
There were considerable variations in oral health status (Table 3): caregiver’s educational attainment was associated with children’s dmft (p < 0.001) and VPI scores (p = 0.01). Family income level was associated with dental caries experience (p < 0.001). Caregiver’s age was significantly associated with child’s dmft (p = 0.03), the younger the age of the parent the more the caries experience. The mean HKREALD-30 score was 23.0 (SD: 3.97, minimum = 9.00, maximum = 30.00) and the mean HKOHLATP score was 43.6 (SD: 5.59, minimum = 21.00, maximum = 52.00). HKREALD-30 scores were significantly correlated with dmft (r = 0.28, p < 0.001) and VPI (r = 0.16, p = 0.006). HKOHLAT-P was also significantly correlated with dmft (r = 0.27, p < 0.001) and VPI (r = 0.12, p = 0.04). HKREALD30 scores were moderately correlated with HKOHLAT-P scores (r = 0.52, p < 0.001) with the lower the word recognition score (HKREALD-30) the lower the score in comprehension (HKOHLAT-P). Due to evidence of multicollinearity between OHL instruments (HKREALD-30 and HKOHLAT-P) they were considered in separate regression models. Both the unadjusted dental caries status (dmft) and VPI models identified that HKREALD-30 score was associated with a reduced likelihood of having a dental caries experience: unadjusted model (IRR 0.92, p < 0.001) and adjusted model (IRR 0.96, p = 0.03). HKOHLAT-P score was also associated with a reduced likelihood of having a dental caries experience: unadjusted model (IRR 0.95, p < 0.001) and adjusted model (IRR 0.97, p = 0.02). In the adjusted caries models, educational attainment of caregivers was also found to be associated with child dental caries experience (p < 0.001), Table 4. For the adjusted VPI model that accounted for sociodemographic factors, only HKOHLAT-P (but not HKREALD-30) remained significantly associated with a reduced VPI score (IRR 0.90, p = 0.03).
4. Discussion and conclusion 4.1. Discussion Dental caries experience was common among the child participants, and this is consistent with most recent reports in the community; however, the mean dental caries experience was somewhat higher than previously estimated locally [38]. This may indicate a reversal of the lowering trend of caries among preschool children as reported in economically developed countries elsewhere [39,40]. Caries, however, remains a major health issue with the 2011 IOM report indicating that tooth decay was 5 times more common than asthma among children aged 5–7 years [13]. The generally poor oral hygiene status also concurs with previous local population reports with almost all participating children exhibiting evidence of plaque accumulation [38]. Socio-demographic variations in clinical oral health status were substantial. Parental educational attainment was associated with dental caries status and VPI. Family income level was associated with dental caries status. These findings concur with local and international studies of socio-demographic disparities [41–44]. The OHL scores were high relative to the possible range of scores on both HKREALD-30 and HKOHLAT-P. Both literacy measures were moderately correlated with each other, indicating that while both measures were assessing a similar concept (OHL); they were also assessing distinctly different attributes (‘word recognition’ versus ‘OHL comprehension’). Mainstream research has established ‘literacy’ as a multidimensional concept with definitions of what constitutes reading and reading comprehension evolving beyond mere explicit recall, word recognition and mastery of phonemic decoding to examining the relationship between text types and the social world [8,45]. To date, health literacy and OHL studies have worked from less complex perspectives relying on more limited definitions of functional literacy and relying on rapid estimates
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using word recognition. Whilst faster to administer, the results of this study have highlighted that, in order to provide more in-depth understandings of health literacy as a complex concept, a more robust, tailor-made health literacy assessment instrument specific to the literacy demands of the particular healthcare context such as HKOHLAT-P is required. Both caregiver’s HKREALD-30 and HKOHLAT-P were significantly associated with children’s dental caries status and VPI. The direction of the correlation was as expected – ‘negative’; however the strength of the correlation could best be described as ‘modest’ (r < 0.30) [46]. In negative binomial regression analyses accounting for socio-demographic factors, both HKREALD-30 and HKOHLAT-P were associated with dental caries status. Only HKOHLAT-P was also associated with VPI, thus showing that HKOHLAT-P was a more robust measure in predicting children’s oral health. This may be related to the greater complexity of HKOHLAT-P [8,34] in assessing factual knowledge and conceptual understanding literacy rather than merely word recognition as in HKREALD-30 [33]. Whilst education remained an important caregiver variable for child oral health status, additional literacy assessments, particularly those examining comprehension, may assist in further exploring the multifactorial issues at play in the association between caregiver variables and child health. Evidence supports the role of functional literacy indicated in Nutbeam’s conceptual model [6]. More work is needed to further explore interactive, communicative and critical literacy in oral health, and to further consider how these may be conceptualized in Asian contexts. The present results should be considered in light of the study’s limitations. First, the study documented only concurrent correlations and the direction of causality remains unclear. Second, the data was collected from kindergartens on Hong Kong Island only – an area comprised of people from higher socio-economic levels than for the Hong Kong Special Administrative Region (HKSAR) in general. As almost 70% of the sample had a monthly income of HKD 20,000 (Table 1b), this might not be representative of the entire population of pre-school child/parent dyads living in the HKSAR. Finally, the developed instruments focus only on the functional domain of OHL, which is one of the possibly three dimensions identified in the literature to date [3]; however, this domain was assessed comprehensively using two validated instruments. Although HKREALD-30 has a major advantage of easy administration, like other word recognition tests, it is recognized as less adequate in assessing comprehension [47]. A more complex instrument such as HKOHLAT-P, which assesses conceptual knowledge within this functional domain of OHL, offers more robust assessment. It should be noted that the readability of the stimulus texts was not evaluated as the study’s focus examined patients’ ability to understand the currently available OHL materials developed locally by clinicians and health promotion providers. Since written and spoken Cantonese are different from Mandarin and other Chinese dialects, further research is needed to extrapolate HKOHLAT-P to other Chinese dialects. Hence, recommendations are made for future studies to test these instruments in more diverse populations. Additionally, more work on readability of health materials in Chinese contexts is warranted. A wider limitation across the field of OHL is that baseline literacy levels as to what constitutes ‘low’, ‘average’ or ‘high’ levels of literacy have not as yet been determined [18]. This study has indicated associations but has not identified cut-offs. A larger and more diverse sample size will help establish valid cut-off points. 4.2. Conclusion The main conclusion of this study was that caregiver OHL was associated with their child’s oral health status. The
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comprehension task (HKOHLAT-P) was more robust in determining such associations when compared to a simple word recognition test (HKREALD-30). 4.3. Practice implications These results have the potential to inform the paediatric oral health agenda in Hong Kong and beyond. It can also serve as a guide for future OHL research designs in non-English contexts. Furthermore, these results have implications for general public health education as they provide necessary baseline information for designing wider community-level interventions. Conflict of interest None. Acknowledgements The authors acknowledge the financial support provided by the Research Grants Council of Hong Kong (Ref: 760009). We also appreciate the research assistance provided by Ms. Lee Tsui Man Jenny, Ms. Li Kar Yan, undergraduate and postgraduate student research assistants at the Faculty of Dentistry, The University of Hong Kong. We also sincerely thank the participating schools and families for their support for this project. References [1] Kickbusch IS, Maag D. Health literacy: towards active health citizenship. In: Springer M, editor. Public health in Osterreich and Europa. Graz: Festschrift Horst Noack; 2006. p. 151–8. [2] Scottish Government. Health literacy – a scoping study. Final Report, Edinburgh, Scotland; 2009, Available from: www.scotland.gov.uk/Publications/ 2009/12/16090906/1 [accessed 15.09.13]. [3] Nutbeam D. Health promotion glossary. Health Promot Int 1998;13:349–64. [4] Rudd RE, Horowitz AM. Health and literacy: supporting the oral health research agenda. J Public Health Dent 2005;65:131–2. http://dx.doi.org/ 10.1111/j.1752-7325.2005.tb02801.x. [5] US Department of Health and Human Services. Health Communication. Healthy people 2010. 2nd ed. Washington, DC: US Government Printing Office; 2000, Available from: http://www.healthypeople.gov/2010/Document/HTML/ Volume2/21Oral.htm [accessed 06.12]. [6] Nutbeam D. Health literacy as a public health goal: a challenge for contemporary health education and communication strategies into the 21st century. Health Promot Int 2000;15:259–67. [7] Nutbeam D. The evolving concept of health literacy. Soc Sci Med 2008;67:2072–8. http://dx.doi.org/10.1016/j.socscimed.2008.09.050. ISSN: 0277-9536. [8] Bridges SM, Parthasarathy DS, Au TKF, Wong HM, Yiu CKY, McGrath CP. Development of functional oral health literacy assessment instruments: application of literacy and cognitive theories. J Public Health Dent 2013. http:// dx.doi.org/10.1111/jphd.12033. [9] Alexander RE. Readability of published dental educational materials. J Am Dent Assoc 2000;131:937–42. [10] Lee JY, Rozier RG, Lee S-YD, Bender D, Ruiz RE. Development of a word recognition instrument to test health literacy in dentistry: the REALD-30 – a brief communication. J Public Health Dent 2007;67:94–8. [11] Richman JA, Lee JY, Rozier RG, Gong DA, Pahel BT, Vann WF. Evaluation of a word recognition instrument to test health literacy in dentistry REALD-99. J Public Health Dent 2007;67:99–104. [12] Gong DA, Lee JY, Rozier RG, Pahel BT, Richman JA, Vann Jr WF. Development and testing of the test of functional health literacy in dentistry (TOFHLiD). J Public Health Dent 2007;67:105–12. [13] IOM. Advancing oral health in America. Washington, DC: The National Academies Press; 2011 , Available from: www.nap.edu/openbook.php?record_id=13086 [cited/accessed 17.09.12]. [14] IOM (Institute of Medicine). Oral health literacy: workshop summary. Washington, DC: The National Academies Press; 2013 , Available from: www.nap.edu/catalog.php?record_id=13484 [cited/accessed 17.09.13]. [15] HHS. Healthy people 2020. Office of Disease Prevention and Health Promotion; 2010, Available from: http://www.cdc.gov/nchs/healthy_people/hp2020.htm [cited/accessed 17.09.12]. [16] HHS. National action plan to improve health literacy. Washington, DC: Office of Disease Prevention and Health Promotion; 2010 , Available from: www.health.gov/communication/hlactionplan [cited/accessed 17.09.12].
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[33] Wong HM, Bridges SM, Yiu CKY, McGrath CPJ, Au TK, Parthasarathy DS. Development and validation of Hong Kong rapid estimate of adult literacy in dentistry. J Invest Clin Dent 2012;3:118–27. [34] Wong HM, Bridges SM, Yiu CKY, McGrath CPJ, Au TK, Parthasarathy DS. Validation of Hong Kong Oral Health Literacy Assessment Task for Paediatric Dentistry (HKOHLAT-P). Int J Paediatr Dent 2013. http://dx.doi.org/10.1111/ipd.12021. [35] Paul LM, editor. Ethnologue: languages of the world. 16th ed., Dallas, TX: SIL International; 2009 . Available from: http://www.ethnologue.com [accessed 11.12]. [36] World Health Organization. Oral health methods and indices. WHO Oral Health Country/Area Profile Programme. Geneva, Switzerland: World Health Organization; 1997. [37] Ainamo J, Bay I. Problems and proposals for recording gingivitis and plaque. Int Dent J 1975;25:229–35. [38] The Government of Hong Kong Special Administrative Region, Department of Health, Oral Health Survey. Common dental disease and oral health related behavior; 2001, Available from: www.dh.gov.hk/english/press/2002/02_12_12 [accessed 07.12]. [39] US Department of Health and Human Services, Centers for Disease Control and Prevention (CDC). Healthy people 2020 initiative. Washington, DC: US Government Printing Office; 2012 , Available from: http://www.healthypeople.gov/ 2020/topicsobjectives2020/overview.aspx?topicid=32#four [accessed 11.12]. [40] US Department of Health and Human Services, Centers for Disease Control and Prevention (CDC). Oral health: preventing cavities, gum disease, tooth loss, and oral cancers: at a glance 2010 [Internet]. Atlanta: CDC; 2010, Available from: http://www.cdc.gov/chronicdisease/resources/publications/AAG/doh.htm#aag [cited 08.03.10, accessed 11.12]. [41] IOM. Improving access to oral health care for vulnerable and underserved populations. Washington, DC: The National Academies Press; 2011 , Available from: www.nap.edu/openbook.php?record_id=13116 [cited/accessed 17.09.12]. [42] Zhou Y, Lin HC, Lo EC, Wong MC. Risk indicators for early childhood caries in 2year-old children in Southern China. Aust Dent J 2011;56:33–9. [43] Oliveira LB, Sheiham A, Bonecker M. Exploring the association of dental caries with social factors and nutritional status in Brazilian preschool children. Eur J Oral Sci 2008;116:37–43. [44] Shamta S, Ayyaz AK, Saima C. Maternal factors and child’s dental health. J Oral Health Commun Dent 2009;3:45–8. [45] Cope B, Kalantzis M, editors. Multiliteracies: literacy learning and the design of social futures. London: Routledge; 2000. [46] Dancey C, Reidy J. Statistics without Maths for Psychology: using SPSS for Windows. London: Prentice Hall; 2004. p. 179–81. [47] Macek MD, Haynes D, Wells W, Bauer-Leffler S, Cotten PA, Parker RM. Measuring conceptual health knowledge in the context of oral health literacy: preliminary results. J Public Health Dent 2010;70:197–204.
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Patient Education and Counseling journal homepage: www.elsevier.com/locate/pateducou
Health Literacy
The relationship between caregiver functional oral health literacy and child oral health status Susan M. Bridges a, Divya S. Parthasarathy a, Hai Ming Wong b, Cynthia K.Y. Yiu b, Terry K. Au d, Colman P.J. McGrath c,* a Centre for the Enhancement of Teaching and Learning/Faculty of Education, The University of Hong Kong, Pokfulam, Hong Kong Special Administrative Region b Paediatric Dentistry & Orthodontics, Faculty of Dentistry, The University of Hong Kong, Hong Kong Special Administrative Region c Periodontology & Dental Public Health, Faculty of Dentistry, The University of Hong Kong, Hong Kong Special Administrative Region d Department of Psychology, The University of Hong Kong, Hong Kong Special Administrative Region
A R T I C L E I N F O
A B S T R A C T
Article history: Received 29 April 2013 Received in revised form 30 September 2013 Accepted 26 October 2013
Objective: To describe the relationship between caregivers’ oral health literacy (OHL) and the oral health status of their children in an Asian population. Methods: A random sample of 301 child/caregiver dyads was recruited from kindergartens in Hong Kong. Two locally-developed and validated OHL assessment tasks were administered to caregivers with Hong Kong Rapid Estimate of Adult Literacy in Dentistry-30 (HKREALD-30) assessing word recognition and Hong Kong Oral Health Literacy Assessment Task for Paediatric Dentistry (HKOHLAT-P) assessing comprehension. Their children’s oral health status was assessed [dental caries experience – decayed, missing, filled teeth index – (dmft) and oral hygiene status – Visible Plaque Index (VPI)]. Results: Caregivers’ literacy was associated with children’s oral health status. The HKOHLAT-P had a stronger association with children’s oral health than HKREALD-30. HKOHLAT-P and HKREALD-30 remained associated with dmft in the adjusted negative binomial regression models (accounting for socio-demographics), Incidence Rate Ratio (IRR) 0.97, p = 0.02, and 0.96, p = 0.03, respectively. In the adjusted model, HKOHLAT-P was associated with VPI (IRR 0.90, p < 0.05), but no association between HKREALD-30 and VPI was evident. Conclusion: The main conclusion of this study was that caregiver oral health literacy was associated with their child’s oral health status. A comprehension instrument had a more robust association with children’s oral status than a word recognition instrument. Practice implications: This study has implications for general public health education for designing community-level interventions. ß 2013 Elsevier Ireland Ltd. All rights reserved.
Keywords: Caregiver Oral health literacy Oral health status Child
1. Introduction Debates regarding the conceptualization and definition of health literacy (HL) [1–3] and, more recently, oral health literacy (OHL) [4,5] indicate that the fields continue to be of considerable interest. Nutbeam’s [6,7] notions of health literacy as an outcome of health promotion and as a ‘clinical risk’ or ‘personal asset’ provide a useful conceptual framing. His earlier work [3],
* Corresponding author at: Dental Public Health, Faculty of Dentistry, 3/F Prince Philip Dental Hospital, 34 Hospital Road, Hong Kong Special Administrative Region. Tel.: +852 2859 0513. E-mail addresses: [email protected] (S.M. Bridges), [email protected] (D.S. Parthasarathy), [email protected] (H.M. Wong), [email protected] (Cynthia K.Y. Yiu), [email protected] (T.K. Au), [email protected], [email protected] (Colman P.J. McGrath). 0738-3991/$ – see front matter ß 2013 Elsevier Ireland Ltd. All rights reserved. http://dx.doi.org/10.1016/j.pec.2013.10.018
making the important 3-way distinction between: (i) basic functional literacy; (ii) communicative/interactive literacy; and (iii) critical health literacy articulated some of the aspects of health literacy that are distinguishing the field from mainstream literacy research [8]. The initial and, to date, dominant focus on functional levels of (oral) health literacy is reflected in the definitions in Table 1a. OHL studies adopting a functional focus have yielded fruitful results regarding the readability of health materials [9] and the assessment of patient reading skills, including word recognition [10,11] and comprehension [12]. As a more recent evolution from the HL agenda, particularly in the USA [13–16], OHL is proving to be developing as a distinct field. These distinctions are driven by differences in healthcare contexts which are not only disciplinary in nature (see Table 1a) but also encompass unique, topic-specific communicative events and epidemiological concerns.
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Table 1a Definitions of HL and OHL. Health literacy (1998) [3]
Oral health literacy (2000) [5]
‘‘the cognitive and social skills which determine the motivation and ability of individuals to gain access to, understand and use information in ways which promote and maintain good health’’
‘‘the degree to which individuals have the capacity to obtain, process, and understand basic oral and craniofacial health information and services needed to make appropriate health decisions’’
In the paediatric context, there is substantial evidence in the medical literature indicating significant associations between caregiver’s generic health literacy levels across a range of child health status conditions [17]. However, there is limited information on the relationship between caregiver’s OHL and children’s oral health status [18,19], such as dental caries – one of the most common health problems of childhood [20]. While it is acknowledged that caregivers play a critical role in the prevention and management of children’s oral health status [21], there has been little consideration of the effect of caregiver OHL on children’s oral health. For the most part, oral health studies have focused on associations between caregivers’ OHL and subjective assessments of oral health [22–24]. As a relatively new field arising in western medicine, these studies have been conducted mostly in English dominant countries such as North America [10,11,18,19,22–27], Australia [28,29], Canada [30]. Whilst multilingualism is arising as an area of communication research in oral health [31], studies of OHL in other languages and countries remains in its infancy. There is, however, some pioneer work in SE Asia in establishing validated literacy assessment instruments both using English language India [32] and Asian languages, e.g. Cantonese [33,34]. It is yet to be fully established how OHL can inform our understandings of child oral health status and management in non-English speaking contexts, specifically amongst Chinese linguistic groups. Of these, those who speak the Cantonese dialect and read traditional Chinese script constitute a significant global population in terms of numbers and distribution [35] and, therefore, warrants separate investigation. This study, therefore, aimed to describe the relationship between the functional OHL levels of primary caregivers in a Cantonese population and the clinical oral health status of their preschool children. In addition, the study sought to determine if a complex comprehension literacy instrument had a more robust association with children’s oral health than a simple word recognition test. 2. Methods
were randomly selected to participate. Children were chosen randomly using simple random tables. Their parents were contacted through the kindergartens with an explanation of the objectives of the project and written consent was obtained. Participation was voluntary and no additional efforts were made to enrol the subjects. Eligibility criteria included healthy children who were 5 years of age and were accompanied by the primary caregiver. Children with specific learning disabilities, students requiring learning support, and caregivers who could not read and write Cantonese were excluded from the study. The flow diagram summarizing study recruitment procedures and final participation is shown in Fig. 1. 2.2. Data collection On arrival dyads were assigned identifiers and caregivers underwent literacy assessment while their children underwent clinical examinations; assessments were conducted simultaneously (and blind), so the assessors did not know about the outcomes of the assessment running in parallel. Initial administration of a word-recognition instrument, Hong Kong Rapid Estimate of Adult Literacy in Dentistry-30 (HKREALD-30) [33] to caregivers was conducted as an interview process (administration time: 2 min) by trained calibrated examiners, immediately followed by a comprehension literacy assessment, Hong Kong Oral Health Literacy Assessment Task for Paediatric Dentistry (HKOHLAT-P) [34] which was a ‘‘paper-and-pencil’’ task (administration time: 40 min). It also asked the participants to provide additional background questions on family socio-demographics and caregivers’ self-reported reading habits (administration time: 5 min). Children’s oral health status was assessed by trained and calibrated examiners, using two assessment methods. Dental caries experience was assessed using the methods and criteria as prescribed by the WHO basic oral health survey protocol whereby the number of decayed, missing and filled teeth (dmft) are counted [36]. For the age group in this study, the possible range was 0–20. Additionally, the oral hygiene status of the children was assessed
2.1. Sample This study was approved by the by the Institutional Review Board of the University of Hong Kong/Hospital Authority Hong Kong West Cluster (HKU/HA HKW IRB) (Ref: UW 09-184). A random sample of child/parent dyads were recruited from kindergartens in Hong Kong. The children were 5 years of age (birth dates ranging from December 2004 to December 2005). The sampling frame was comprised of kindergartens on Hong Kong Island with an enrollment of 70 children or more. Using SAS software version 9.3 (SAS institute Inc., Cary, NC, USA) sample power calculation based on Fisher’s Z Test for Pearson Correlation, to have a 90% chance with two-sided test at a 5% significant level for detecting at least a 0.2 correlation identified that 258 subjects would be required. To account for potential non-response of 15%, the aim was to recruit 316 child/parent dyads. One in four kindergartens was selected from Hong Kong Island (40 kindergartens in the sample frame) and a total of ten kindergartens participated. Within each kindergarten, children
Total no of dyads completed the study=301 dyads
Total no of schools selected to participate =10
Total no of participants=316 dyads
Total no of dyads failed to complete the study=15 dyads Fig. 1. Flow diagram of participants enrolled in the study.
S.M. Bridges et al. / Patient Education and Counseling 94 (2014) 411–416 Table 1b Profile of the study population (caregivers and children) (n = 301 dyads).
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2.3. Data analyses
Caregiver and child characteristics
n
%
Caregiver characteristics Gender Mother Father/other caregiver
223 78
74.1 25.9
Educational level Secondary school or lower Above secondary school
155 146
51.5 48.5
Age <40 years 40 years
192 109
63.8 36.2
Income level*
102 199
33.9 66.1
Child characteristics Gender Male Female
134 167
44.5 55.5
*20,000 HKD = 2580 USD.
using the Visible Plaque Index (VPI) [37] which provides a summary score of oral hygiene by recording plaque depositions for various sites around the tooth. VPI is the number of sites with dental plaque divided by number of sites examined and multiplied by 100.
The data analyses was carried out using SPSS statistical software. Descriptive statistics were produced to examine the profile of the study group. Bivariate analyses examined variations in oral health status (dmft and VPI). Correlation analysis (Spearman’s correlation) between the two literacy instruments was conducted. Negative binomial regression models were constructed separately for two key outcome variables – dmft and VPI. As the OHL measures showed evidence of multicollinearity, separate models for with HKREALD-30 and HKOHLAT-P as independent variables were developed. Both unadjusted and adjusted (accounting for socio-demographics and oral health literacy) models were produced.
3. Results Among the 316 dyads recruited, 301 completed all assessments; the completion rate was 95.6%. The socio-demographic profile of the study participants is presented in Table 1b. Three quarters of the children (75.4%, 227) had a dental caries experience (dmft > 0) and the mean dmft was 4.2 (SD 4.5), Table 2. Most of the dental caries experience was related to untreated dental decay: the prevalence of decayed teeth (dt) was 68.8% (207) and the mean dt was 3.3 (SD 3.9). Almost all children had evidence of plaque deposition at one or more sites (99.3%, 299) and the mean VPI was 63.5 (SD 20.4).
Table 2 Clinical oral health status of children: dental caries experience (dmft) and oral hygiene status (VPI) (n = 301 dyads). Clinical oral health status
%
n
Dental caries experience dmft Decayed teeth (dt) Missing teeth (mt) Filled teeth (ft)
75.4 68.8 30.2 7.6
227a 207a 91a 23a
4.2 3.3 0.7 0.2
4.5 3.9 1.3 0.9
0.0 0.0 0.0 0.0
Oral hygiene status VPI
99.3
299b
63.5
20.4
0.0
a b
Mean
SD
Minimum
Maximum 20.0 18.0 6.0 9.0
100
dmft > 0. VPI > 0.
Table 3 Bivariate variations in child’s clinical oral health status with respect to caregiver’s socio-demographic factors. Caregiver and child characteristics
dmft
VPI
Mean (SD)
p-Value
Caregiver characteristics Gender Mother Father/other caregiver
Mean (SD)
p-Value
4.30 (4.46) 4.14 (4.82)
0.80
63.54 (20.71) 63.47 (19.94)
0.98
## Education level Secondary school or lower Above secondary school
5.76 (5.09) 2.66 (3.21)
<0.001
66.38 (19.12) 64.66 (19.77)
0.01
# Age <40 years 40 years
4.67 (4.72) 3.53 (4.14)
0.03
63.13 (20.07) 62.25 (20.68)
0.66
Income level
5.99 (5.18) 3.37 (3.91)
<0.001
66.00 (19.96) 62.25 (20.68)
0.13
# Child characteristics Gender Male Female
4.90 (4.65) 3.75 (4.41)
0.03
65.09 (18.50) 62.26 (21.92)
0.23
##
# ##
p < 0.05. p < 0.001
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Table 4 Findings of negative binomial regression analysis. Variables
Unadjusted model IRR (95% CI, lower–upper)
Variables p-Value
Caries model Model 1.1 ### HKREALD-30
0.92 (0.90–0.96)
<0.001
Model 1.2 HKOHLAT-P
0.95 (0.93–0.97)
<0.001
###
VPI model Model 1.1 HKREALD-30
##
Model 1.2 # HKOHLAT-P
0.98 (0.97–0.99)
0.88 (0.81–0.97)
Adjusted model IRR (95% CI, lower–upper)
p-Value
Caries model Model 2.1 ## Education ## HKREALD-30
1.73 (1.26–2.38) 0.96 (0.92–0.99)
0.001 0.030
Model 2.2 ## Education # HKOHLAT-P
1.73 (1.26–2.38) 0.97 (0.94–0.99)
0.001 0.022
0.007
VPI model Model 2.1 ### Constant
15.33 (11.70–20.10)
0.010
Model 2.2 # HKOHLAT-P
0.90 (0.82–0.99)
<0.001
0.034
Caries model: Model 1.1: Unadjusted model: Dependent variable – (dmft), Independent variables – HKREALD-30. Model 1.2: Unadjusted model: Dependent variable – (dmft), Independent variables – HKOHLAT-P. Model 2.1: Adjusted model: Dependent variable – (dmft), Independent variables – gender, age, income level and education level of caregiver, gender of child, HKREALD-30. Model 2.2: Adjusted model: Dependent variable – (dmft), Independent variables – gender, age, income level and education level of caregiver, gender of child, HKOHLAT-P. VPI model: Model Model Model Model # ##
1.1: Unadjusted model: Dependent variable – (VPI), Independent variables – HKREALD-30. 1.2: Unadjusted model: Dependent variable – (VPI), Independent variables – HKOHLAT-P. 2.1: Adjusted model: Dependent variable – (VPI), Independent variables – gender, age, income level and education level of caregiver, gender of child, HKREALD-30. 2.2: Adjusted model: Dependent variable – (VPI), Independent variables – gender, age, income level and education level of caregiver, gender of child, HKOHLAT-P.
p < 0.05. p < 0.01. p < 0.001.
###
There were considerable variations in oral health status (Table 3): caregiver’s educational attainment was associated with children’s dmft (p < 0.001) and VPI scores (p = 0.01). Family income level was associated with dental caries experience (p < 0.001). Caregiver’s age was significantly associated with child’s dmft (p = 0.03), the younger the age of the parent the more the caries experience. The mean HKREALD-30 score was 23.0 (SD: 3.97, minimum = 9.00, maximum = 30.00) and the mean HKOHLATP score was 43.6 (SD: 5.59, minimum = 21.00, maximum = 52.00). HKREALD-30 scores were significantly correlated with dmft (r = 0.28, p < 0.001) and VPI (r = 0.16, p = 0.006). HKOHLAT-P was also significantly correlated with dmft (r = 0.27, p < 0.001) and VPI (r = 0.12, p = 0.04). HKREALD30 scores were moderately correlated with HKOHLAT-P scores (r = 0.52, p < 0.001) with the lower the word recognition score (HKREALD-30) the lower the score in comprehension (HKOHLAT-P). Due to evidence of multicollinearity between OHL instruments (HKREALD-30 and HKOHLAT-P) they were considered in separate regression models. Both the unadjusted dental caries status (dmft) and VPI models identified that HKREALD-30 score was associated with a reduced likelihood of having a dental caries experience: unadjusted model (IRR 0.92, p < 0.001) and adjusted model (IRR 0.96, p = 0.03). HKOHLAT-P score was also associated with a reduced likelihood of having a dental caries experience: unadjusted model (IRR 0.95, p < 0.001) and adjusted model (IRR 0.97, p = 0.02). In the adjusted caries models, educational attainment of caregivers was also found to be associated with child dental caries experience (p < 0.001), Table 4. For the adjusted VPI model that accounted for sociodemographic factors, only HKOHLAT-P (but not HKREALD-30) remained significantly associated with a reduced VPI score (IRR 0.90, p = 0.03).
4. Discussion and conclusion 4.1. Discussion Dental caries experience was common among the child participants, and this is consistent with most recent reports in the community; however, the mean dental caries experience was somewhat higher than previously estimated locally [38]. This may indicate a reversal of the lowering trend of caries among preschool children as reported in economically developed countries elsewhere [39,40]. Caries, however, remains a major health issue with the 2011 IOM report indicating that tooth decay was 5 times more common than asthma among children aged 5–7 years [13]. The generally poor oral hygiene status also concurs with previous local population reports with almost all participating children exhibiting evidence of plaque accumulation [38]. Socio-demographic variations in clinical oral health status were substantial. Parental educational attainment was associated with dental caries status and VPI. Family income level was associated with dental caries status. These findings concur with local and international studies of socio-demographic disparities [41–44]. The OHL scores were high relative to the possible range of scores on both HKREALD-30 and HKOHLAT-P. Both literacy measures were moderately correlated with each other, indicating that while both measures were assessing a similar concept (OHL); they were also assessing distinctly different attributes (‘word recognition’ versus ‘OHL comprehension’). Mainstream research has established ‘literacy’ as a multidimensional concept with definitions of what constitutes reading and reading comprehension evolving beyond mere explicit recall, word recognition and mastery of phonemic decoding to examining the relationship between text types and the social world [8,45]. To date, health literacy and OHL studies have worked from less complex perspectives relying on more limited definitions of functional literacy and relying on rapid estimates
S.M. Bridges et al. / Patient Education and Counseling 94 (2014) 411–416
using word recognition. Whilst faster to administer, the results of this study have highlighted that, in order to provide more in-depth understandings of health literacy as a complex concept, a more robust, tailor-made health literacy assessment instrument specific to the literacy demands of the particular healthcare context such as HKOHLAT-P is required. Both caregiver’s HKREALD-30 and HKOHLAT-P were significantly associated with children’s dental caries status and VPI. The direction of the correlation was as expected – ‘negative’; however the strength of the correlation could best be described as ‘modest’ (r < 0.30) [46]. In negative binomial regression analyses accounting for socio-demographic factors, both HKREALD-30 and HKOHLAT-P were associated with dental caries status. Only HKOHLAT-P was also associated with VPI, thus showing that HKOHLAT-P was a more robust measure in predicting children’s oral health. This may be related to the greater complexity of HKOHLAT-P [8,34] in assessing factual knowledge and conceptual understanding literacy rather than merely word recognition as in HKREALD-30 [33]. Whilst education remained an important caregiver variable for child oral health status, additional literacy assessments, particularly those examining comprehension, may assist in further exploring the multifactorial issues at play in the association between caregiver variables and child health. Evidence supports the role of functional literacy indicated in Nutbeam’s conceptual model [6]. More work is needed to further explore interactive, communicative and critical literacy in oral health, and to further consider how these may be conceptualized in Asian contexts. The present results should be considered in light of the study’s limitations. First, the study documented only concurrent correlations and the direction of causality remains unclear. Second, the data was collected from kindergartens on Hong Kong Island only – an area comprised of people from higher socio-economic levels than for the Hong Kong Special Administrative Region (HKSAR) in general. As almost 70% of the sample had a monthly income of HKD 20,000 (Table 1b), this might not be representative of the entire population of pre-school child/parent dyads living in the HKSAR. Finally, the developed instruments focus only on the functional domain of OHL, which is one of the possibly three dimensions identified in the literature to date [3]; however, this domain was assessed comprehensively using two validated instruments. Although HKREALD-30 has a major advantage of easy administration, like other word recognition tests, it is recognized as less adequate in assessing comprehension [47]. A more complex instrument such as HKOHLAT-P, which assesses conceptual knowledge within this functional domain of OHL, offers more robust assessment. It should be noted that the readability of the stimulus texts was not evaluated as the study’s focus examined patients’ ability to understand the currently available OHL materials developed locally by clinicians and health promotion providers. Since written and spoken Cantonese are different from Mandarin and other Chinese dialects, further research is needed to extrapolate HKOHLAT-P to other Chinese dialects. Hence, recommendations are made for future studies to test these instruments in more diverse populations. Additionally, more work on readability of health materials in Chinese contexts is warranted. A wider limitation across the field of OHL is that baseline literacy levels as to what constitutes ‘low’, ‘average’ or ‘high’ levels of literacy have not as yet been determined [18]. This study has indicated associations but has not identified cut-offs. A larger and more diverse sample size will help establish valid cut-off points. 4.2. Conclusion The main conclusion of this study was that caregiver OHL was associated with their child’s oral health status. The
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comprehension task (HKOHLAT-P) was more robust in determining such associations when compared to a simple word recognition test (HKREALD-30). 4.3. Practice implications These results have the potential to inform the paediatric oral health agenda in Hong Kong and beyond. It can also serve as a guide for future OHL research designs in non-English contexts. Furthermore, these results have implications for general public health education as they provide necessary baseline information for designing wider community-level interventions. Conflict of interest None. Acknowledgements The authors acknowledge the financial support provided by the Research Grants Council of Hong Kong (Ref: 760009). We also appreciate the research assistance provided by Ms. Lee Tsui Man Jenny, Ms. Li Kar Yan, undergraduate and postgraduate student research assistants at the Faculty of Dentistry, The University of Hong Kong. We also sincerely thank the participating schools and families for their support for this project. References [1] Kickbusch IS, Maag D. Health literacy: towards active health citizenship. In: Springer M, editor. Public health in Osterreich and Europa. Graz: Festschrift Horst Noack; 2006. p. 151–8. [2] Scottish Government. Health literacy – a scoping study. Final Report, Edinburgh, Scotland; 2009, Available from: www.scotland.gov.uk/Publications/ 2009/12/16090906/1 [accessed 15.09.13]. [3] Nutbeam D. Health promotion glossary. Health Promot Int 1998;13:349–64. [4] Rudd RE, Horowitz AM. Health and literacy: supporting the oral health research agenda. J Public Health Dent 2005;65:131–2. http://dx.doi.org/ 10.1111/j.1752-7325.2005.tb02801.x. [5] US Department of Health and Human Services. Health Communication. Healthy people 2010. 2nd ed. Washington, DC: US Government Printing Office; 2000, Available from: http://www.healthypeople.gov/2010/Document/HTML/ Volume2/21Oral.htm [accessed 06.12]. [6] Nutbeam D. Health literacy as a public health goal: a challenge for contemporary health education and communication strategies into the 21st century. Health Promot Int 2000;15:259–67. [7] Nutbeam D. The evolving concept of health literacy. Soc Sci Med 2008;67:2072–8. http://dx.doi.org/10.1016/j.socscimed.2008.09.050. ISSN: 0277-9536. [8] Bridges SM, Parthasarathy DS, Au TKF, Wong HM, Yiu CKY, McGrath CP. Development of functional oral health literacy assessment instruments: application of literacy and cognitive theories. J Public Health Dent 2013. http:// dx.doi.org/10.1111/jphd.12033. [9] Alexander RE. Readability of published dental educational materials. J Am Dent Assoc 2000;131:937–42. [10] Lee JY, Rozier RG, Lee S-YD, Bender D, Ruiz RE. Development of a word recognition instrument to test health literacy in dentistry: the REALD-30 – a brief communication. J Public Health Dent 2007;67:94–8. [11] Richman JA, Lee JY, Rozier RG, Gong DA, Pahel BT, Vann WF. Evaluation of a word recognition instrument to test health literacy in dentistry REALD-99. J Public Health Dent 2007;67:99–104. [12] Gong DA, Lee JY, Rozier RG, Pahel BT, Richman JA, Vann Jr WF. Development and testing of the test of functional health literacy in dentistry (TOFHLiD). J Public Health Dent 2007;67:105–12. [13] IOM. Advancing oral health in America. Washington, DC: The National Academies Press; 2011 , Available from: www.nap.edu/openbook.php?record_id=13086 [cited/accessed 17.09.12]. [14] IOM (Institute of Medicine). Oral health literacy: workshop summary. Washington, DC: The National Academies Press; 2013 , Available from: www.nap.edu/catalog.php?record_id=13484 [cited/accessed 17.09.13]. [15] HHS. Healthy people 2020. Office of Disease Prevention and Health Promotion; 2010, Available from: http://www.cdc.gov/nchs/healthy_people/hp2020.htm [cited/accessed 17.09.12]. [16] HHS. National action plan to improve health literacy. Washington, DC: Office of Disease Prevention and Health Promotion; 2010 , Available from: www.health.gov/communication/hlactionplan [cited/accessed 17.09.12].
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