Association of Population Health Literacy and Social Vulnerability: Implications for Health Communication

Theoretical Background and research questions/hypothesis:  Health literacy is an individual’s ability to understand and act upon health information. Currently, health literacy is only measured at the individual level in clinical settings. A population level assessment would make a significant contribution to the development of public health messages that aim to improve health outcomes of communities. Health literacy may improve knowledge, skills, and behaviors for better health outcomes. Limited health literacy is a barrier for disease management, self-efficacy for healthy behaviors and treatment adherence. An assessment that captures the reciprocal relationship between the individual and the social environment may evolve health literacy assessment from the individual to population level. This project examines a multivariate assessment model, the Demographic Assessment for Health Literacy (DAHL), to estimate population health literacy and the associations with community-level social vulnerability to further knowledge of the relationship between the social environment and health literacy.

Methods and Results (informing the conceptual analysis):  Demographic data from the 2012 Behavioral Risk Factor Surveillance System was used to calculate a DAHL score for residents of four Georgia counties (N=1177). The DAHL begins with a reference score and subtracts points for lower education, race/ethnic minority, older age, and gender. Social Vulnerability Index (SVI) percentiles are from the 2010 Georgia county census data as calculated by ATDSR. DAHL and SVI values were compared by county using separate one-way ANOVAs. Pearson’s correlation coefficients were computed to examine the association of DAHL with overall SVI percentile of the county and the four themes: socioeconomic status, household composition, race/ethnicity/language, and housing/transportation. Two counties had significantly higher DAHL scores than the others ([-2.75,-4.85],p=0.05). Overall SVI and all four themes were different by county (p<0.0001), where DeKalb was most vulnerable and Cobb was least vulnerable. DAHL decreased as SVI percentile increased (r=-0.174,p<0.0001). There was weak inverse association between DAHL and the SVI themes of socioeconomic status (r=-0.170,p<0.001), race/ethnicity/language (r=-0.07,p=0.01), and housing/transportation (r=-0.190,p<0.0001). There was weak positive association between high DAHL and household composition (r=0.108;p=0.0002).

Conclusions:  DAHL scores varied at the county level, and were associated with social vulnerability as measured by the SVI. To confirm its ability to detect differences in population health literacy, the DAHL should be further tested in diverse geographic areas and expanded to include younger adult age groups in the scoring calculation. The DAHL is a practical model for population health literacy assessment as existing, publicly available surveillance data may be used to compute scores. Health communicators may use the DAHL to tailor health promotion messages for their target audiences.

Implications for research and/or practice:  Standardizing population health literacy assessment as part of an audience analysis closes a surveillance gap and identifies areas in greatest need for tailored health messages. Health communicators can produce tailored messages in plain language by following the National Plan to Improve Health Literacy and utilizing the CDC Clear Communication Index. Future studies may consider further examination of the strength of association between social determinants of health and health literacy to define a population indicator of health literacy.