Effects of health literacy interventions on health-related outcomes in socioeconomically disadvantaged adults living in the community: a systematic review.

OBJECTIVES The objectives of this review were: i) to identify and synthesize the best available evidence on the effectiveness on health-related outcomes of health literacy interventions for enabling socioeconomically disadvantaged people living in the community to access, understand, appraise and apply health information; and ii) to identify components of health literacy interventions associated with improved health-related outcomes. INTRODUCTION Health literacy is defined as a person's competence in accessing, understanding, appraising and applying health information in order to make sound health decisions. A high level of health literacy is positively related to better health outcomes. However, nearly half of the American and European populations have low health literacy levels. Socioeconomically disadvantaged groups in particular present with the weakest health literacy levels, suggesting that differences in health literacy levels contribute to health disparities. Therefore, there is a need to understand the conditions under which health literacy interventions aiming at improving health-related outcomes among socioeconomically disadvantaged people can be implemented. INCLUSION CRITERIA This review considered studies on socioeconomically disadvantaged adults living in the community identified using the socially stratifying PROGRESS factors (Place of residence, Race/ethnicity, Occupation, Gender, Religion, Education, Socioeconomic status, Social capital). This review considered studies evaluating the following interventions: i) targeting health literacy based on either a clinical and/or a public health approach, ii) delivered at the individual, interpersonal, community or societal level, iii) delivered by any healthcare/social work professional, and iv) using a single or multicomponent strategy. The comparator was no treatment, standard care or a variation of the intervention. All randomized and non-randomized controlled trials as well as quasi-experimental designs were included. Outcomes considered were: i) health-related quality of life and health-related outcomes, ii) health behavior outcomes, and iii) outcomes related to the access and use of healthcare services. METHODS A three-step strategy was conducted for primary research published up to May 2018 across seven databases without any language restriction. A search for gray literature was also conducted. Titles and abstracts were screened for assessment against the inclusion criteria. Studies that met the inclusion criteria were retrieved in full and then assessed in detail against the inclusion criteria. Critical appraisal was undertaken using the standardized critical appraisal instruments from JBI. Data were extracted from included studies using standardized data extraction tools from JBI. A meta-analysis was not possible; findings have been presented in a narrative form. RESULTS Twenty-one studies were included in the review. Three studies addressed the health literacy competency of understanding health information, and 18 addressed the competency of applying health information. Thirteen studies were found as effective based on a variety of health-related outcomes (mainly clinical outcomes), preventive health practices and behaviors, and health-promoting behaviors. Results enabled identification of some effective intervention operational components, including cultural appropriateness, tailoring, skills building, goal setting and active discussions. Multi-faceted interventions, combining both an information transfer medium and contact with an interventionist, appear to be more effective than single modality interventions. The use of an appropriate theoretical foundation is also an important factor for successful interventions. CONCLUSION To improve health-related outcomes among socioeconomically disadvantaged people, health literacy interventions are more likely to be successful if they are theory-based, are multi-faceted and use person-centered operational components such as cultural appropriateness, tailoring, skills building, goal setting and active discussions.