Newest Vital Sign as a proxy for medication adherence in older adults

Objective: To assess the utility of the Newest Vital Sign (NVS) as a proxy for medication adherence in community-dwelling older adults. Design: Descriptive cross-sectional study. Setting: 12 adult day care centers in the Lisbon metropolitan area, Portugal, between March and May 2009. Participants: 100 white community-dwelling older adults. Intervention: Participants were administered the NVS, Single Item Literacy Screener (SILS), and self-reported Measure of Adherence to Therapy (MAT). Main outcome measures: Health literacy and medication adherence. Results: The mean (+/- SD) age of the respondents was 73.3 +/- 7.8 years and 71% were women. The NVS score was 0.81 +/- 0.10 (of 6 possible points), and 95% of the respondents scored in the three lowest possible scores, indicating a notable floor effect. Age was found to be inversely correlated with NVS score (P = 0.003). The MAT score was 36.2 +/- 4.7 (range 17-42). No statistically significant association between the NVS and level of education (P = 0.059 [Kruskal-Wallis]), gender (P = 0.700 [Mann-Whitney]), SILS (P = 0.167), or MAT (P = 0.379) was identified. Conclusion: The utility of the NVS as a proxy for medication adherence in community-dwelling older adults is limited because of a floor effect that hinders its predictive power for medication adherence.