[Developing a Japanese version of the Digital Health Literacy Instrument].

Objectives　The Internet has made it possible to search for, obtain, transmit, and share information. Accordingly, the ability to use health information and skills related to interactivity taken from the Internet have become important in the medical and health fields. However, there is no scale to evaluate these abilities. Therefore, this study was conducted to assess the validity and reliability of the Digital Health Literacy Instrument (DHLI) and examine the association of digital health literacy (DHL) with the characteristics of the study participants.Methods　The Japanese version of the DHLI was developed using the basic guidelines for scale translation. The participants included 2,000 Japanese adults (men: 50.0%, mean age: 40.7±12.0 years) who responded to an Internet-based cross-sectional survey. The Japanese version of the DHLI, attributes, sources of health information, contents of health information taken from the Internet, and eHealth Literacy Scale (eHEALS) scores were obtained using a questionnaire. Confirmatory factor analysis and correlation with eHEALS scores were used to assess construct and criterion validities. Cronbach's alpha and correlation coefficients were computed for internal consistency and test-retest reliability. Differences in DHLI scores for each attribute and variables related to health information were examined using the analysis of variance and t-test.Results　Confirmatory factor analysis revealed a goodness-of-fit index of .946, a comparative fit index of .969, and a root mean square error of approximation of .054, confirming that the Japanese version has the same seven-factor structure as the original version does. A significant positive correlation was found between DHLI and eHEALS scores (r=.40, P<.001). Cronbach's alpha was .92, and test-retest reliability was r=.88 (P<.001). DHLI scores were mainly associated with household income, health status, frequency of information searches on the Internet, and devices used. The subscale scores found difficulties in evaluating reliability, determining relevance, and adding self-generated content. Differences in DHL were observed among some sources and contents of health information on the Internet.Conclusion　The Japanese version of the DHLI was a sufficiently reliable and valid instrument for assessing DHL among Japanese adults. Our results suggest that low DHL may lead to health information disparities. Therefore, it is necessary to consider support strategies for individuals who need to improve their DHL and for skills that need to be strengthened.