Electronic supplementary material
The online version of this article (doi:10.1186/s12889-015-2251-y) contains supplementary material, which is available to authorized users.
An erratum to this article can be found at http://dx.doi.org/10.1186/s12889-015-2419-5.
An erratum to this article is available at http://dx.doi.org/10.1186/s12889-015-2419-5.
The authors declare that they have no competing interests.
BG developed the protocol for the study, conducted the literature searches, selected studies for inclusion in the review, conducted the quality assessment, interpreted the data and wrote the manuscript. JSB and YKL assisted in designing the search strategy, selecting studies for inclusion in the review, conducting the quality assessment, and interpreting the data. CJMJ and CS critically reviewed the manuscript for content. SAR was involved in drafting the manuscript and had an advisory role throughout the study. AFW was involved in the development of the protocol, designing the search strategy, interpretation of the data, and had an advisory role. All authors contributed substantially to the writing of the manuscript and have read and approved the final manuscript.
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Low health literacy is a common problem among older adults. It is often suggested to be associated with poor adherence. This suggested association implies a need for effective adherence interventions in low health literate people. However, previous reviews show mixed results on the association between low health literacy and poor adherence. A systematic meta-review of systematic reviews was conducted to study the association between health literacy and adherence in adults above the age of 50. Evidence for the effectiveness of adherence interventions among adults in this age group with low health literacy was also explored.
Eight electronic databases (MEDLINE, ERIC, EMBASE, PsycINFO, CINAHL, DARE, the Cochrane Library, and Web of Knowledge) were searched using a variety of keywords regarding health literacy and adherence. Additionally, references of identified articles were checked. Systematic reviews were included if they assessed the association between health literacy and adherence or evaluated the effectiveness of interventions to improve adherence in older adults with low health literacy. The AMSTAR tool was used to assess the quality of the included reviews. The selection procedure, data-extraction, and quality assessment were performed by two independent reviewers. Seventeen reviews were selected for inclusion.
Reviews varied widely in quality. Both reviews of high and low quality found only weak or mixed associations between health literacy and adherence among older adults. Reviews report on seven studies that assess the effectiveness of adherence interventions among low health literate older adults. The results suggest that some adherence interventions are effective for this group. The interventions described in the reviews focused mainly on education and on lowering the health literacy demands of adherence instructions. No conclusions could be drawn about which type of intervention could be most beneficial for this population.
Evidence on the association between health literacy and adherence in older adults is relatively weak. Adherence interventions are potentially effective for the vulnerable population of older adults with low levels of health literacy, but the evidence on this topic is limited. Further research is needed on the association between health literacy and general health behavior, and on the effectiveness of interventions.