This study established and validated a health literacy model at the individual level. This model included socio-demographic characteristics, prior knowledge, health literacy, health behavior and health status. It is a simple empirical model rather than a complicated conceptual model.
Socio-demographic characteristics as basic determinants
In the model, socio-demographic characteristics are the basic factors. In this research, a number of socio-demographic factors were tested, such as gender, ethnicity, marital status, and occupation. There was no significant difference between genders and ethnic groups when it came to measurements of health literacy. The main reason is that the awareness of the public on the prevention of infectious respiratory disease has been greatly increased with various intervention activities being conducted after the outbreak of Severe Acute Respiratory Syndromes (SARS) in 2003 and the outbreak of Highly Pathogenic Avian Influenza in 2006 in China. There was, however, a significant difference between the unmarried and married group, but the difference is explainable by age differences. In addition, there was a significant difference in health literacy across three categories of occupation. Highest health literacy scores were seen among students, scientific and technical workers, teachers and doctors. Office workers, service providers, general workers and other workers scored lower, while farmers and retired people scored lower still. Due to the strong relationship between education level and subsequent occupation, the effect of occupation on health literacy reflected the effect of education on health literacy in a similar fashion. Therefore, the model incorporated only three important factors: age, education and income.
Undoubtedly, educational background is the most important factor. In a structural equation, the coefficient of education background on health literacy was 2.35, which indicates that with each level of education (classified as primary school, junior high school, senior high school, college and graduate students), participants score almost 2.35 points more in the health literacy test, which is roughly equivalent to understanding eight percent more health information in daily life. This indicates how important education is for the promotion of health literacy. Education has the same strong effect on prior knowledge, and a further indirect effect on health literacy though prior knowledge. As an important social source of information, the effect of higher education levels on health literacy has been demonstrated in many studies [6, 16]. In this study, we confirmed the quantitative relationship between education and health literacy, and the standardized coefficient (β)was 0.35 almost same with Cho’s study (β = 0.33) [16].
Age is the second important factor. Through careful measurement, we find that prior knowledge and health literacy tend to increase slightly among younger age groups, but then decrease significantly with age among the older age groups. Therefore, targeting the under-30 age group for the popularization and publicity of health literacy program – when perception and behavior form and develop stably – can promote their health skills and knowledge, bringing them lifetime benefits. For those aged over 30, health communication and health education must be consolidated due to the downward trend of knowledge and health literacy with aging. Conversely, the study found older age groups’ health status was better than that of the younger groups, with the 30–39 age group as the dividing point. This finding is contrary to what other studies have measured. The main reason for this is that the health status category was only concerned with the frequency an individual got a cold and the severity of such sicknesses because it is relatively easier and more feasible to measure the frequency of catching a cold and its severity than other kinds of infectious respiratory diseases. As we know, older people have often developed stronger resistance to these illnesses than younger people. For example, Kumar’s review of H1N1 flu shows that the virus is causing critical illnesses mostly in young adults. The researchers concluded that H1N1 (swine flu) primarily affects young adults who are in relatively good health and free of underlying illnesses [27].
Income is the weakest of the three influencing factors in this study. It has only a slight effect on prior knowledge. Usually, those of higher individual incomes own more sources of knowledge. Therefore, the measured negative effect of income on health behavior is an unexpected phenomenon, though the standardized coefficient is very little and the t value of -2.1416 is only just significant. Therefore, the relationship between income and prior health knowledge needs further research to confirm.
Effects of prior knowledge
In this study, prior knowledge is defined as an individual’s knowledge at the time before reading, watching or listening to the health-related materials. Baker’s article cited the report of the Institute of Medicine’s expert panel, and gave a more expansive definition of health literacy which included conceptual knowledge as part of health literacy [20]. However, more researchers view conceptual knowledge or prior knowledge as a resource or a moderator that a person has, which facilitates health literacy, but does not in itself constitute health literacy [21–23, 28]. This study finds that prior knowledge has a strong direct effect on health literacy. That is to say that a person with more health knowledge is better able to obtain, comprehend and use health information.
Determinants of health behavior and health status
In the model, we confirmed that health literacy and prior knowledge are the top two determinants of health behavior. Prior knowledge’s effect on health behavior stands to reason, for example in the KAP model [29]. Health behavior and health status are interactional. In Baker’s model, health literacy is one of many factors that lead to the acquisition of new knowledge, more positive attitudes, greater self-efficacy, positive health behaviors, and better health outcomes [20]. In von Wagner’s model, health outcomes depend on a range of mediating processes, most obviously actions to promote health, prevent disease, or comply with diagnosis and treatment, which the author calls health actions [22]. In Paasche-Orlow and Wolf’s 2007 model, they proposed causal pathways between limited health literacy and health outcomes [21]. Their models distinguish three different types of health actions that mediate the impact of health literacy on health: access to and utilization of health care, patient–provider interaction, and self-care. In this study, health behavior mainly focused on self-care and utilization of health care, while health status reflected health outcome. However, health behavior and health status did not show a good relationship. The measurement of health status in this study was conditioned to respiratory infection due to the restriction of the project scope. It is obvious that respiratory infections are influenced by many things, not only individual behavior, but also a variety of biological and social factors. Therefore, the relationship between health behavior and health outcomes, and the effect of health literacy on health outcomes though health behavior need further study to validate.