Development and Validation of the HL6: a Brief, Technology-Based Remote Measure of Health Literacy

Background Most health literacy measures require in-person administration or rely upon self-report. Objective We sought to develop and test the feasibility of a brief, objective health literacy measure that could be deployed via text messaging or online survey. Design Participants were recruited from ongoing NIH studies to complete a phone interview and online survey to test candidate items. Psychometric analyses included parallel analysis for dimensionality and item response theory. After 9 months, participants were randomized to receive the final instrument via text messaging or online survey. Participants Three hundred six English and Spanish-speaking adults with >= 1 chronic condition Main Measures Thirty-three candidate items for the new measure and patient-reported physical function, anxiety, depression, and medication adherence. All participants previously completed the Newest Vital Sign (NVS) in parent NIH studies. Key Results Participants were older (average 67 years), 69.6% were female, 44.3% were low income, and 22.0% had a high school level of education or less. Candidate items loaded onto a single factor (RMSEA: 0.04, CFI: 0.99, TLI: 0.98, all loadings >.59). Six items were chosen for the final measure, named the HL6. Items demonstrated acceptable internal consistency (alpha=0.73) and did not display differential item functioning by language. Higher HL6 scores were significantly associated with greater educational attainment (r=0.41), higher NVS scores (r=0.55), greater physical functioning (r=0.26), fewer depressive symptoms (r=-0.20), fewer anxiety symptoms (r=-0.15), and fewer barriers to medication adherence (r=-0.30; all p<.01). In feasibility testing, 75.2% of participants in the text messaging arm completed the HL6 versus 66.2% in the online survey arm (p=0.09). Socioeconomic disparities in completion were more common in the online survey arm. Conclusions The HL6 demonstrates adequate reliability and validity in both English and Spanish. This performance-based assessment can be administered remotely using commonly available technologies with fewer logistical challenges than assessments requiring in-person administration.