BackgroundHealth literacy, or the ability to access, understand, appraise and apply health information, is central to individuals’ health and well-being. A comprehensive, concept-based measure of most dimensions of health literacy has been developed for the general population in Europe, which enables comparisons within and between countries. This study seeks to validate this tool for use in Japan, and to use a Japanese translation to compare health literacy levels in Japan and Europe.MethodsA total of 1054 Japanese adults recruited through an Internet research service company, completed a Japanese-language version of the 47-item European Health Literacy Survey Questionnaire (HLS-EU-Q47). The survey was administered via an online questionnaire, and participant demographics were closely matched to those of the most recent Japanese national census. Survey results were compared with those previously reported in an eight-country European study of health literacy.ResultsInternal consistency for the translated questionnaire was valid across multiple metrics. Construct validity was checked using confirmatory factor analyses. The questionnaire correlated well with existing scales measuring health literacy and mental health status. In general, health literacy in the Japanese population was lower than in Europe, with Japanese respondents rating all test items as more difficult than European respondents. The largest difference (51.5 %) was in the number of respondents finding it difficult to know where to get professional help when they are ill.ConclusionsThis study translated a comprehensive health literacy questionnaire into Japanese and confirmed its reliability and validity. Comparative results suggest that Japanese health literacy is lower than that of Europeans. This discrepancy may be partly caused by inefficiency in the Japanese primary health care system. It is also difficult to access reliable and understandable health information in Japan, as there is no comprehensive national online platform. Japanese respondents found it more difficult to judge and apply health information, which suggests that there are difficulties in health decision-making in Japan.Numerous issues may be linked to lower levels health literacy in Japan, and further studies are needed to improve this by developing individual competencies and building supportive environments.Electronic supplementary materialThe online version of this article (doi:10.1186/s12889-015-1835-x) contains supplementary material, which is available to authorized users.

BackgroundHealth inequities are increasing worldwide, with mounting evidence showing that the greatest cause of which are social determinants of health. To reduce inequities, a lot of citizens need to be able to access, understand, appraise, and apply information on the social determinants; that is, they need to improve health literacy on social determinants of health. However, only a limited number of scales focus on these considerations; hence, we developed the Health Literacy on Social Determinants of Health Questionnaire (HL-SDHQ) and examined its psychometric properties.MethodsWe extracted domains of the social determinants of health from “the solid facts” and related articles, operationalizing the following ten domains: “the social gradient,” “early life,” “social exclusion,” “work,” “unemployment,” “social support,” “social capital,” “addiction,” “food,” and “transport,” Next, we developed the scale items in the ten extracted domains based on the literature and included four aspects of health literacy (ability to access, understand, appraise, and apply social determinants of health-related information) in the items. We also evaluated the ease of response and content validity. The self-administered questionnaire consisted of 33 items. The reliability and construct validity were verified among 831 Japanese adults in an internet survey.ResultsThe scale items had high reliability with a Cronbach’s alpha of 0.92, and also adequate results were obtained for the internal consistency of the information-processing dimensions (Cronbach’s alpha values were 0.82, 0.91, 0.84, and 0.92 for accessing, understanding, appraising, and applying, respectively). The goodness of fit by confirmatory factor analysis based on the four dimensions was an acceptable value (comparative fit index = 0.901; root mean square error of approximation = 0.058). Furthermore, the bivariate relationship between HL-SDHQ and the frequency of participation in citizen’s activities was similar to the theoretical results.ConclusionsHL-SDHQ clarifies the relationship between the ten domains of the social determinants of health and health in each domain and is able to measure whether it is possible to access, understand, appraise, and apply related information. The reliability and validity of the scale were adequate.Electronic supplementary materialThe online version of this article (doi:10.1186/s12889-016-3971-3) contains supplementary material, which is available to authorized users.

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