Determinants of health literacy in Iran: a systematic review and meta-analysis of quantitative studies (2001-2024)

Health literacy is a critical social determinant of health and a key lever for reducing health inequities. Understanding its determinants is essential for designing effective public health interventions.

This study aimed to synthesize quantitative evidence on the individual- and contextual-level determinants of health literacy among the Iranian population.

Following PRISMA 2020 guidelines, we systematically searched PubMed, Scopus, Web of Science, Cochrane Library, and Iranian databases (SID, Magiran) for observational and interventional studies published between January 2001 and December 2024. Eligible studies used quantitative designs, assessed health literacy using validated instruments (e.g., HLS-Iran, TOFHLA), were conducted among Iranian populations, and reported sufficient statistical data to calculate effect sizes. Two independent reviewers conducted screening and data extraction; disagreements were resolved by a third reviewer. Study quality was appraised using STROBE and CONSORT checklists. Effect sizes were harmonized as standardized mean differences (Hedges' g) with 95% confidence intervals (CIs) and pooled using random-effects models (REML) in Stata version 16.0. Heterogeneity was assessed using I² and Cochran's Q. Subgroup analyses, meta-regression, and sensitivity analyses were performed where applicable.

Ninety-seven primary studies were included. Among demographic determinants, educational attainment showed the largest association (k=18; g=0.65, 95% CI: 0.55-0.75), followed by urban residence (k=10; g=0.35, 95% CI: 0.22-0.48); age, gender, and marital status showed small and imprecise associations. Psychological determinants showed strong positive associations, particularly self-efficacy (k=12; g=0.58, 95% CI: 0.46-0.70) and self-esteem (k=9; g=0.51, 95% CI: 0.39-0.63), whereas social-geographic isolation was negatively associated (k=7; g=-0.38, 95% CI: -0.52 to -0.24). Among cultural determinants, digital literacy (k=8; g=0.52, 95% CI: 0.40-0.64) and cultural capital (k=7; g=0.47, 95% CI: 0.36-0.58) were positively associated, while traditional lifestyle adherence showed a negative association (k=6; g=-0.31, 95% CI: -0.44 to -0.18). Economic determinants revealed that household income was positively associated (k=13; g=0.48, 95% CI: 0.36-0.60), whereas the Gini coefficient (k=8; g=-0.42, 95% CI: -0.55 to -0.29) and inflation (k=5; g=-0.28, 95% CI: -0.40 to -0.16) were negatively associated. Among social determinants, quality of life showed the strongest positive association (k=14; g=0.60, 95% CI: 0.50-0.70), followed by social support in healthcare (k=11; g=0.45, 95% CI: 0.35-0.55). Moderate-to-substantial heterogeneity was observed across most estimates (I²: 46%-63%). Sensitivity analyses and Egger tests did not reveal significant changes in estimates or consistent publication bias.

Health literacy in Iran is shaped by a complex interplay of psychological, socio-economic, cultural, and geographic factors, with education, quality of life, self-efficacy, and digital literacy emerging as the strongest determinants. Multilevel interventions-spanning educational development, digital inclusion, poverty reduction, psychosocial support, and community engagement-are needed to address these determinants and advance health equity.