Objective: To determine the prevalence of low health literacy and investigate the relationship between low health literacy and physical and psychological wellbeing in the Japanese general population.
Methods: A web-based cross-sectional survey was conducted in a national sample of Japanese adults. Health literacy was measured by self-report using the validated single-item screening question, "How confident are you filling out forms by yourself?" Wellbeing was measured with the physical and psychological domains of the World Health Organization Quality of Life Assessment-BREF. Effect sizes were computed by dividing the mean difference in scores by the standard deviation of the scores of all participants.
Results: In 1040 adult enrollees (mean age, 57-year-old; women, 52%), there were 161 (15.5%; 95% confidence interval [CI], 13.3-17.7%) with low health literacy. Individuals with low health literacy reported lower physical wellbeing (60.6 vs. 71.7, p<0.001) and psychological wellbeing (59.7 vs. 68.3, p<0.001) compared with those with adequate health literacy. After adjusting for sociodemographic characteristics, health risk behaviors and chronic conditions, these differences were still significant (physical wellbeing, p<0.001; psychological wellbeing, p<0.001). The effect sizes of the difference of scores were moderate for physical wellbeing (-0.55) and also for psychological wellbeing (-0.44).
Conclusion: The prevalence of self-reported low health literacy in Japanese adults is substantial and it is independently associated with poorer physical and mental wellbeing.
Practice implications: Efforts to monitor health literacy and to evaluate causal pathways to poor wellbeing should be encouraged in the Japanese population.