Background: Robust tools to assess self-reported adolescent functional health literacy are lacking. In Portugal, the only available tool is the Newest Vital Sign for Portuguese adolescents (NVS-PTeen), though presenting modest validity and reliability properties. A new instrument-the Functional Literacy Questionnaire (FLiQ)-was developed, inspired by the NVS-PTeen, but following the European Regulation for food labeling and targeting a balanced assessment of numeracy and verbal comprehension skills. This study aimed to evaluate several psychometric properties of the FLiQ when administered to Portuguese adolescents.
Methods: We conducted a longitudinal observational study with three phases: (1) Delphi panel with health literacy experts; (2) self-administration of FLiQ and NVS-PTeen to adolescents in 7th to 9th grades; and (3) re-administration of FLiQ four weeks after baseline, to the same group of participants.
Results: FLiQ's content validity was excellent, with an Average-Content Validity Index of .95. Overall, 372 adolescents (50.3% girls) aged between 12-17 years (median age: 13) participated in the study. Of these, 150 completed the test-retest assessment. Internal consistency was good (Kuder-Richardson Fornula-20 = .70), as well as test-retest reliability (Intraclass Coefficient Correlation = .82). FLiQ total score was weakly correlated with the school year (rho = .174), and moderately with Portuguese (rho = .348) and Mathematics grades (rho = .333). Factor analysis indicated a two-dimension structure, reflecting numeracy and verbal comprehension skills. Item response theory analysis revealed differences in difficulty and discrimination capacity among items, all with adequate fit values.
Conclusion: FLiQ is a valid and reliable tool. It can be used to monitor functional health literacy levels in Portuguese adolescents.
Copyright: © 2024 Martins et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.