The Brazilian validation of a health literacy instrument: the newest vital sign

Objective: This study aimed to perform the cross-cultural adaptation and validation of the NVS for Brazilian Portuguese.

Material and methods: Two hundred and fifty adults responded to the adapted version of the NVS, the Brazilian version of the Rapid Estimate of Adult Literacy in Dentistry (BREALD-30), ten questions of the National Functional Literacy Index (NFLI), and a questionnaire about demographic and oral health-related aspects. Statistical analysis determined the internal consistency, stability, difficulty of items, and convergent/discriminant/predictive validities of the NVS. p < .05 was considered significant.

Results: The NVS displayed a good internal consistency (Cronbach's alpha = 0.79) and a fair stability (ICC = 0.57; 0.39-0.70 95% CI). Seventy-two percent of participants answered the easier question (#5) correctly, whereas only 28.4% were successful in responding the most difficult question (#1). The convergent validity of the NVS was demonstrated by its significant correlation with the BREALD-30 (Rs = 0.601, p < .001) and NFLI (Rs = 0.544, p < .001). The observation of higher NVS scores among health professionals, white and more educated people confirmed the discriminant validity of the instrument. Moreover, health literacy was a significant predictor of self-reported oral health and reason for dental utilization.

Conclusion: The NVS demonstrated adequate psychometric properties to be applied in Brazilian oral health epidemiological surveys.