Factor structure of the Newest Vital Sign in English-speaking adults with and without HIV disease.

Abstract

Low health literacy is prevalent in both healthy and clinical populations, and plays a critical role in health behaviors and outcomes. The Newest Vital Sign (NVS) is a performance-based screening measure of health literacy that assesses numeracy, prose literacy, and document literacy. However, the underlying factor structure of the NVS is not well established and questions persist regarding optimal scoring methods, which limits our understanding of this widely-used measure. The current study therefore aimed to confirm the factor structure of the NVS in separate samples of healthy, English-speaking adults and people with HIV (PWH). The study samples consisted of English-speaking adults without HIV (n = 270) and PWH (n = 310) who completed the 6-item NVS. Confirmatory factor analysis was used to test one-, two-, and three-factor models for the items on the NVS. A five-item, single factor solution for the NVS provided the best fit to the data and showed configural invariance between the samples of healthy adults and PWH. Findings provide evidence for the construct validity of a revised, five-item scoring of the NVS in a clinical and non-clinical sample of English-speaking adults. Future research is needed to examine the psychometrics and construct validity of this revised NVS in other clinical populations. Results of this factor analytic study suggest that researchers and clinicians are well supported in using a single, five-item score from the NVS to assess health literacy in people with chronic medical conditions.