International application of health literacy measures: adaptation and validation of the newest vital sign in The Netherlands

The newest vital sign assesses individual reading and numeracy skills. The aim of this study was to create a Dutch version (NVS-D) and to assess its feasibility, reliability, and validity in The Netherlands. We performed a qualitative study among experts (n=27) and patients (n=30) to develop the NVS-D and to assess its feasibility. For validation, we conducted a quantitative survey (n=329). Reliability was assessed by Cronbach's alpha. Construct validity was examined by analyzing association patterns. Receiver operating characteristic (ROC) curves determined optimal cut-off scores. Cronbach's alpha was 0.76. In accordance with a priori hypotheses we found strong associations between NVS-D, general vocabulary, prose literacy and objective health literacy, and weaker associations between NVS-D and subjective health literacy. A score of ≥4 out of 6 best distinguished individuals with adequate versus inadequate health literacy. The results suggest that the NVS-D is a reliable and valid tool that allows international comparable health literacy research in The Netherlands. The NVS-D can be applied in research on the role of health literacy in health and health care, and the development of interventions. The methods can be applied in cross-cultural adaptation of health literacy measures in other countries