How Do Subjective Health Literacy Measures Work in Young Adults? Specifying "Online'' or "Paper-Based'' Forms Impacts Results

Purpose. There is no gold-standard health literacy measure. The Single Item Literacy Screener (SILS) and Subjective Literacy Screener (SLS) ask people to self-report ability to understand health information. They were developed in older adults, before common use of electronic health information. This study explored whether the SILS and SLS related to objective literacy, numeracy, and comprehension among young adults, and whether specifying ``online'' or ``paper-based'' wording affected these relationships. Methods. Eligible individuals (18-35 years of age, Englishspeaking, US residents) from an online survey company were randomized to 1) original measures; 2) measures adding ``paper-based'' to describe health information/forms; or 3) measures adding ``online'' to describe health information/forms. We examined how each measure related to e-Health Literacy (eHEALS), subjective numeracy (SNS), objective numeracy (ONS), and comprehension of a short passage. Results. A total of 848/1342 respondents correctly answered attention-checks and were analyzed. The validated SILS related to comprehension (P = 0.003), eHEALS (P = 0.04), and ONS (P \ 0.001) but not SNS (P = 0.44). When adding ``paper-based,'' SILS related to eHEALS (P \ 0.001) and ONS (P = 0.003) but did not relate to comprehension (P = 0.25) or SNS (P = 0.35). When adding ``online,'' SILS related to comprehension (P \ 0.001), eHEALS (P \ 0.001), ONS (P = 0.005), and SNS (P = 0.03). The validated SLS related to comprehension (P \ 0.001), eHEALS (P \ 0.001), ONS (P \ 0.001), and SNS (P \ 0.001). When adding ``paper-based,'' the SLS only related to eHEALS (P = \0.001) and comprehension (P = 0.03) but did not relate to ONS (P = 0.13) or SNS (P = 0.33). When adding ``online,'' the SLS related to comprehension (P \ 0.001), eHEALS (P \ 0.001), and SNS (P = 0.03) but not ONS (P = 0.06). Conclusions. Young adults might interpret subjective health literacy measures differently when prompted to think about electronic or paper-based information. Researchers should consider clearer instructions or modified wording when using these measures in this population.