Health literacy, health status, and healthcare utilization of Taiwanese adults: results from a national survey

Low health literacy, defined as an individual's limited ability to obtain, process, and understand basic health information and services needed to make appropriate health decisions [1], has been suggested as a worldwide problem and a global challenge for the 21st century [2]. In its recent report, the WHO Commission on the Social Determinants of Health (CSDH) declares health literacy as a major determinant for health and advises countries to create a multi-stakeholder Council on Health Literacy to monitor and coordinate strategic activities to enhance health literacy [3].

The declaration of health literacy as a global challenge and the CSDH's recommendation of health literacy initiatives as important elements in the strategies to reduce health inequity are largely based on studies in the United States and a few other English-speaking countries. Those studies indicated a high prevalence of low health literacy in adults and found that low health literacy was linked to limited understanding of health information and medical instructions [4‐7], inadequate self-management of diseases [6], underuse of preventive services and routine physician visits [8‐13], increased hospitalizations and medical costs [14, 15], and high mortality rates [16]. So far, little research on health literacy has been conducted in non-English-speaking countries. It is unclear if low health literacy is a worldwide problem and whether low health literacy also has adverse health effects in countries that have more equitable access to health care.

In this paper, we report the results of a national assessment of health literacy in Taiwanese adults. The purpose is twofold: (1) to assess the prevalence and distribution of low health literacy in Taiwanese adults, and (2) to examine the associations of low health literacy with self-rated physical and mental health status and health care utilization (outpatient clinic visits, hospitalization, and emergency room visits). The results would help to confirm if low health literacy is indeed a worldwide health threat, even in a country where the literacy rate is 97.8% and where 22.48% of the adult population has a university degree [17]. Furthermore, we could learn how health literacy contributes to health status and health care utilization in an equitable health care system. Implemented in 1995, Taiwan's national health insurance system has increased the coverage from 57% to 98% of the population. The system has also expanded access by waiving copayments for the very poor, veterans, and aboriginal populations [18].

In a population-based, nationally representative sample of Taiwanese adults, approximately 30% had either inadequate or marginal health literacy. By comparison, 36% of American adults surveyed in the 2003 National Assessment of Adult Literacy (NAAL) had below basic (can perform simple everyday literacy activities) and basic health literacy (can perform no more than the most simple and concrete literacy activities) [23]; and 11.4% and 15.5% of adults in the U.K. and Japan, respectively, were considered to have low health literacy in national surveys [13, 24]. However, this comparison is imprecise, because no similar tests have been developed to allow for international comparison. For example, instead of using a scale, the Japanese survey measured health literacy based on a single-item screening question, "How confident are you filling out forms by yourself?," possibly under-estimating the percentage of adults with low health literacy.

Similar to findings in the NAAL [21] and previous health literacy studies [4, 13, 23, 25‐28], older age, poorer educational attainment, and lower income were found to be associated with lower levels of health literacy in Taiwan. Furthermore, Taiwanese adults living in less populated and more rural areas tended to have a lower level of health literacy than adults living in more populated and more urban areas. Taken together, these findings suggest low health literacy is not only a personal limitation but also an indication of disadvantaged social status.

Contrary to our expectation, health literacy was not associated with self-rated physical health after controlling for age, gender, educational attainment, household income, and residential location. Although inadequate health literacy was significantly correlated with poor self-rated mental health, the association between health literacy and self-rated mental health was limited in the multinomial logit model. These findings are surprising because most studies have shown a significant relationship between health literacy and self-rated health status [25, 26, 29‐31]. One possible explanation for the difference is that previous studies were conducted primarily on patients recruited from clinics or older adults enrolled in a managed care plan; these patients may in general have poorer health than the general adult population. Alternatively, the limited contribution of health literacy to health status, over and beyond that of educational attainment, may be due to a high correspondence between health literacy and educational attainment in Taiwanese adults. If this is true, educational attainment would be a sufficient indicator of health literacy skills among Taiwanese adults and health literacy assessment would have limited value. Furthermore, a focus on reducing educational disparities in health may help to decrease the health burden of poor health literacy as well.

Also interesting was our findings that health literacy was not independently associated with health care utilization among Taiwanese adults. Current evidence on health literacy as a predictor for health care utilization is decidedly mixed. Baker and colleagues found that patients in outpatient clinics who had inadequate health literacy were more likely to have physician visits and be hospitalized [14, 29], while other studies did not find health literacy to be associated with physician visits, use of ER, or hospitalization [4, 32]. Based on our step-wise analysis results that age, educational attainment and household income jointly explained the associations between health literacy and health care utilization, we suspect that the inconsistencies observed in existing literature may result from inadequate consideration of socio-demographic factors. Alternatively, the finding of no association between health literacy and health care utilization may be due to the fact that needed health care is affordable and accessible to around 98% of the population in Taiwan.

Several study limitations are worth noting. The limitations also point to opportunities for future research. First, only self-rated measures of health status and health care utilization were examined in the study. The reliability of self-rated health care utilization, in particular, may be subject to recall bias or memory failure. Linking health literacy test results to medical claims data would provide a more reliable assessment of the consequences of low health literacy. Second, results reported in the study were obtained from a cross-sectional survey and no causality is established between health literacy and health status and health care utilization. A longitudinal study that follows the study sample and reassesses their health outcomes at a later time would help to discern the causal effects of health literacy. Third, the MHLS, similar to other health literacy assessments, is primarily a reading and comprehension test. It offers no indication about the respondent's communication skills, which may be equally important in determining an individual's ability to effectively navigate today's complex health care system. Fourth, a significant proportion of the sample was missing household income information. This may introduce systematic bias in the multinomial logit models. Although a separate analysis was conducted to assess the bias using imputed household income, the results should be interpreted with caution. Finally, we did not examine the associations of health literacy with disease knowledge, self-care skills, and health behaviors. To the extent that disease knowledge, self-care skills and health behaviors are important determinants for health, examining their associations with health literacy may help to devise interventions to improve the health of disadvantaged subgroups of the population.

From our study it is evident that low health literacy is widespread even in countries such as Taiwan that have a high rate of literacy. This finding lends support to the claim that low health literacy may be prevalent around the world. However, the prevalence itself is not necessarily indicative of the need for interventions. As our results suggest, the health effects of low health literacy may vary as a result of the socio-demographic composition of the population and the structure of the health care delivery and financing systems. To the extent this is true, interventions that focus solely on enhancing health literacy may have a limited impact on health and health care utilization in certain countries. Further research that examines the impact of low health literacy on health outcomes across countries would help to verify our contention and inform health policy in other countries.