Detecting limited health literacy in Brazil: development of a multidimensional screening tool

Screening questions have been proposed as practical tools for detecting limited functional health literacy, but have achieved only moderate accuracy in previous studies. We hypothesized that a combination of screening questions and demographic characteristics could better predict a patient's functional health literacy. Three hundred and twenty-two hospital users from São Paulo, Brazil, were interviewed for demographic information and answered questions about literacy habits and perceived difficulties. The Short Test of Functional Health Literacy in Adults was used to classify individuals as having adequate or limited functional health literacy. Of the 322 participants, 102 (31.7%) presented limited functional health literacy. The final logistic model included six predictors. The three demographic variables were educational attainment, mother's educational attainment and major lifetime occupation (manual or non-manual). The three questions concerned 'frequency of use of computers', 'difficulty with writing that have precluded the individual from getting a better job' and 'difficulty reading the subtitles while watching a foreign movie'. A simple score was derived to constitute a practical tool we named the Multidimensional Screener of Functional Health Literacy (MSFHL). The sensitivity of the MSFHL in detecting limited functional health literacy was 81.4% and the specificity was 87.7%, with an area under receiver operating characteristic (ROC) curve of 0.93 (95% CI 0.89-0.95). The MSFHL was better than educational attainment in accurately classifying functional health literacy status (p = 0.0018). We have developed a screening tool based on three demographic characteristics and three simple questions which provides an accurate prediction of a patient's functional health literacy level.