Background: Health literacy research seems to lack a consensus on what aspects to include into literacy in the context of health and on how to operationalize these concepts for measurement purposes. In addition to health literacy, several other concepts, such as electronic health (eHealth) literacy and mental health literacy, have been developed across disciplines. This study examines how these different concepts are used when studying health-related competencies in Web contexts.

Objective: This study systematically reviews health literacy concepts and definitions and their operationalization in studies focused on Web-based health information environments.

Methods: A systematic literature search was conducted in April 2016 in 6 electronic databases with a limitation to articles in English published between January 2011 and April 2016. Altogether, 1289 unique records were identified and screened according to the predefined inclusion criteria: (1) original, peer-reviewed research articles written in English; (2) the topic of the article concerned literacy in the context of health; (3) informants of the study were lay people, not health professionals or students of the field; and (4) the focus of the study was placed on an Web-based information environment. In total, 180 full texts were screened, of which 68 were included in the review. The studies were analyzed with an emphasis on the used health literacy concepts and measures.

Results: On the basis of the included studies, several concepts are in use when studying health-related literacy in Web environments, eHealth literacy and health literacy being the most common ones. The reviewed studies represent a variety of disciplines, but mostly medical sciences. Typically, quantitative research methods are used. On the basis of the definitions for health literacy, 3 thematic categories were identified: general and skill-based, multidimensional, and domain-specific health literacy. Most studies adopted a domain-specific concept, followed by the ones that used a general and skill-based concept. Multidimensional concepts occurred least frequently. The general health literacy concepts were usually operationalized with reading comprehension measures, the domain-specific concepts with self-efficacy measures, and multidimensional concepts with several types of measures. However, inconsistencies in operationalization were identified.

Conclusions: The results show that in studies conducted in Web-based information environments, several different health literacy concepts are in use, and there is no clear consensus on the definitions for these concepts. Future studies should place emphasis on the conceptual development of health literacy in Web contexts to gain better results on operationalization for measurement. Researchers are encouraged to provide clear operational definitions for the concepts they use to ensure transparency in reporting.