Short Assessment of Health Literacy (SAHL) in Portugal: development and validation of a self-administered tool

The goal of this study was to adapt, improve and validate a short, self-administered health literacy assessment tool for European Portuguese-speaking adults. Health literacy tools are of great importance to health authorities and professionals, as low or inadequate health literacy, that is, a limited capacity to handle health-related information, is associated with higher morbidity and mortality. The 18-item Short Assessment of Health Literacy for Brazilian Portuguese-speaking adults (SAHLPA-18) was adapted into European Portuguese. The European Portuguese tool (SAHLPA-23) includes five additional items. The SAHLPA-23 was tested in a convenience sample of 503 participants from two Portuguese regions. Socio-demographic data, literacy and cognitive indicators were collected. Participants also completed a questionnaire on comprehension of written health materials. Construct validity was assessed through correlations between SAHLPA-23 scores and education, literacy, and cognitive variables and score on the comprehension questionnaire. The psychometric properties of the new tool were compared with those of the SAHLPA-18. The mean SAHLPA-18 and SAHLPA-23 scores were 13.9 (77.2%; SD=2.9) and 18.3 (79.6%; SD=3.8), respectively. Both tools showed adequate reliability (Cronbach's α>0.7). SAHLPA-23 was more highly correlated with all study variables than SAHLPA-18. Although both instruments displayed acceptable discriminative power, SAHLPA-23 had better accuracy than SAHLPA-18 (DeLong's method: ΔAUC=0.09, Z=3.36; P<0.001). The SAHLPA-23 is an independent, feasible and innovative tool for estimation of health literacy in the Portuguese adult population.