While defined in various ways, health literacy (HL) generally describes the observable skills required to access, comprehend, evaluate, and apply information to make informed health-related decisions. These capabilities vary among individuals, making limited HL a widespread challenge for health policy and clinical practice. It often prevents patients from understanding health information, such as medication and discharge instructions, informed consent documents, insurance applications, and health education materials.1
Global reports highlight the prevalence of this issue. The 2003 National Assessment of Adult Literacy (NAAL) found that 36% of United States adults possessed basic or below-basic HL. In comparison, the European Health Literacy Project (HLS-EU) – surveying 8 EU states – reported a 12.4% rate of inadequate HL. The HLS-EU project further identified socioeconomic disadvantage, social status, education, age, and gender as predictors of limited HL.1
Oral health literacy (OHL) is increasingly recognized as an important factor influencing patient outcomes. Research indicates that OHL is essential for reducing oral health disparities and promoting oral health and overall wellness. Patients with limited OHL face an increased risk of oral diseases and often struggle to navigate preventive services, adhere to treatment instructions, and maintain self-care routines. As a result, low OHL has been associated with higher healthcare costs and increased mortality risks. Evidence from multiple reports, including the Carolina Oral Health Literacy (COHL) study, suggests that OHL strongly influences both health behaviors and related outcomes.1
However, a systematic review assessing the association between OHL and oral conditions concluded that this association remains unsubstantiated, primarily due to the low quality of the existing research. Nevertheless, other studies support the broader assertion that HL plays a role in health-related decisions and overall health status. Because shared health determinants – such as income, education, and individual characteristics – influence both health behaviors and oral health outcomes, it is hypothesized that an association exists between levels of HL and OHL.1
To address this gap, a cross-sectional study was designed to assess levels of HL and OHL across sociodemographic factors and to explore a possible association between them.1
The Study
This was an online, cross-sectional observational study conducted in Portugal between May 24 and June 21, 2022. It used a convenience sample of individuals aged 16 years or older, recruited via email and WhatsApp. Participants provided informed consent before completing a 12-minute questionnaire hosted on Google Forms.1
The survey assessed HL through 16 questions across 3 domains: healthcare, health promotion, and disease prevention. Participants rated the difficulty of health-related tasks on a 4-point scale. Total scores ranged from 0 to 50 and were categorized into 4 levels: inadequate, problematic, sufficient, and excellent.1
OHL was measured separately via 17 items evaluating reading comprehension, numeracy, active listening, and decision-making, with total scores ranging from 0 to 17 and categorized as inadequate, marginal, or adequate. Additionally, sociodemographic data were collected, including sex, age, education level (participant and their parents), and whether participants were health professionals or students of a health-related field.1
Data were analyzed using descriptive statistics to summarize the sample’s characteristics and literacy distributions. To compare OHL and HL levels across sociodemographic groups (e.g., by age or education), non-parametric tests were used because the data were not normally distributed. Additionally, a correlation test assessed the association between HL and OHL scores. Findings were considered statistically significant at p-values less than 5% (p < 0.05).1
The Results
Out of 205 responses, 204 valid questionnaires were analyzed, and the mean participant age was 30.6 years. The convenience sample was predominantly female, and the health-related group was primarily composed of students (70%). The study found that 14.7% and 25% of the surveyed population had inadequate levels of HL and OHL, respectively.1
Participants’ general HL results:
- Inadequate: 7%
- Problematic: 1%
- Sufficient: 9%
- Excellent: 3%
Participants’ OHL results:
- Inadequate: 25%
- Adequate: 75%1
No statistically significant differences in HL levels were found based on sex, age, or participant/parent education level. However, health professionals and health-related students demonstrated significantly higher rates of excellent HL and lower rates of inadequate HL compared to those not in the health field.1
Conversely, the comparison of OHL with sociodemographic variables showed several statistically significant differences. Females demonstrated higher frequencies of adequate levels and lower frequencies of inadequate levels. Younger participants, those with higher education, and those whose parents had higher education levels also had significantly higher adequate levels. Participants who were health professionals or health-related students also scored significantly higher OHL levels.1
A significant positive, though weak, correlation was observed between HL and OHL levels (p < 0.001). The authors note that these findings are consistent with other Portuguese studies. When compared with a larger European study, the percentage of people with inadequate HL was higher than in countries like Ireland and Spain but lower than in Austria and Bulgaria, suggesting that low HL remains a widespread public health concern influenced by national systems, policies, and economic conditions.1
Limitations
This study has limitations that should be considered. Both HL and OHL were assessed using self-reported tools that lack objective measures of functional literacy. The sample was small (n = 204) and non-random (convenience sampling), with health-related participants primarily consisting of students, limiting the generalizability of the results to broader populations. The cross-sectional design also prevents conclusions about cause and effect.1
Conclusion
This study found that 25% of participants had inadequate levels of OHL, and approximately 60% demonstrated inadequate or problematic general HL. Sociodemographic variables showed a differential impact: being a health professional or health-related student improved HL, while sex, age, education, and connection to the health field influenced OHL.1
These trends may reflect factors such as greater utilization of preventive dental services by women, the positive impact of targeted oral health programs for youth, and the educational benefits of health-related training. A key finding was a weak but statistically significant positive correlation between HL and OHL, suggesting that levels of one could influence those of the other.1
The authors recommend that future research use larger, more representative samples to investigate whether HL is associated with more detailed measures of oral health care utilization. Citing prior research, they also suggest that future OHL investigations incorporate measures of conceptual health knowledge and explore the pathways between HL and oral health, and the importance of assessing HL in dental care.1
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Reference
1. Veladas, F.M.V., De la Torre Canales, G., de Souza Nobre, B.B., et al. Do Sociodemographic Factors Influence the Levels of Health and Oral Literacy? A Cross-Sectional Study. BMC Public Health. 2023; 23(1): 2543. https://pmc.ncbi.nlm.nih.gov/articles/PMC10731678/
