Objective: To evaluate the published literature on the effects of complex (multi-faceted) interventions intended to improve the health-related outcomes of individuals with limited literacy or numeracy.
Methods: We undertook a systematic review of randomized and quasi-randomized controlled trials with a narrative synthesis. The search strategy included searching eight databases from start date to 2007, reference checking and contacting expert informants. After the initial screen, two reviewers independently assessed eligibility, extracted data and evaluated study quality.
Results: The searches yielded 2734 non-duplicate items, which were reduced to 15 trials. Two interventions were directed at health professionals, one intervention was literacy education, and 12 were health education/management interventions. The quality of the trials was mixed, 13/15 trials were conducted in North America, and all focused on literacy rather than numeracy. 13/15 trials reported at least one significant difference in primary outcome, all favoring the intervention group. Only 8/15 trials measured direct clinical outcomes. Knowledge and self-efficacy were the class of outcome most likely to improve.
Conclusion: A wide variety of complex interventions for adults with limited literacy are able to improve some health-related outcomes.
Practice implications: This review supports the wider introduction of interventions for people with limited literacy, particularly within an evaluation context.