Types of participants
This review will consider all studies that include adults (18 years or over) receiving care or adults who are proxies of incompetent health care users or of children (parents or guardians) who have been actively involved in an informed consent process regarding health care procedures.
Participants may be healthy or may have any kind of physical disability, be recruited in any type of health care environment, including acute (hospital), primary care, psychiatric and aged care, in any health specialty, including medicine, dentistry and pharmacy. Studies whose participants have cognitive impairment will be excluded. Studies on informed consent processes for research participants will be also excluded.
Types of intervention(s)
The interventions, methods, and strategies will be included if:
- they aim to improve the informed consent process related to health issues among health care users or their proxies,
- they are designed taking into consideration health literacy as a main concept, and
- the intervention is provided by any health care provider.
Such interventions my focus on either the material provided (e.g. readability, processability), or the supportive procedure of informed consent (e.g. video) in order to decrease the health literacy level required for making an informed choice.
Types of comparators
The comparator will be any traditional or usual or standardized informed consent information procedure.
Types of outcomes
This review will consider studies that include the following outcome measures:
Assessment of decision related to informed consent (was the choice informed?), comprehension or understanding, knowledge, decisional conflict, satisfaction, recall of the information, anxiety or attitude regarding the involvement in the decision.
This review will consider studies that use any instrument, whether validated or not, to assess one or more of the above mentioned outcomes. Studies using unvalidated instruments will be not excluded because this criterion is not clearly relevant for some of the outcomes (e.g. comprehension, knowledge).
Types of studies
This review will consider any randomized controlled trials (RCT) that examine the effectiveness of interventions considering health literacy on the informed consent process for health care users. In the absence of RCTs any other quantitative designs, such as non-randomized experimental and quasi experimental, before and after studies, prospective and retrospective cohort studies, case control studies, case series/case reports and observational studies, will be considered for inclusion in a narrative summary. This review will exclude papers which describe qualitative studies, expert opinion texts, editorials and conference papers.
The search strategy aims to find both published and unpublished studies. A three-step search strategy will be utilized in this review. An initial limited search will be undertaken followed by an analysis of the text words contained in the title and abstract, and of the index terms used to describe the article. A second search using all identified keywords and index terms will then be undertaken across all included databases. Thirdly, the reference list of all identified reports and articles will be searched for additional studies. Studies published in English, French and Greek will be considered for inclusion in this review. No limits by publication date will be imposed on the systematic review. Search strategies for individual databases will be developed in conjunction with a research librarian.
The databases to be searched include:
Medline Ovid, CINAHL, EMBASE, PsycINFO, Cochrane Central Register of controlled Trials
The search for unpublished studies will include:
New York Academy of Medicine Grey Literature Report, Google Scholar, National Library of Medicine and National Institute of Health literature information resources
Initial keywords to be used will be:
Informed consent, informed choice, decision making (all combined with OR) AND
Health literacy, information literacy, numeracy, readability, comprehension, understanding (all combined with OR)
Assessment of methodological quality
Papers selected for retrieval will be assessed by two independent reviewers for methodological validity prior to inclusion in the review using standardized critical appraisal instruments from the Joanna Briggs Institute Meta-Analysis of Statistics Assessment and Review Instrument (JBI-MAStARI) (Appendix I). Any disagreements that arise between the reviewers will be resolved through discussion, or with a third reviewer.
Data will be extracted from papers included in the review using the standardized data extraction tool from JBI-MAStARI (Appendix II). The data extracted will include specific details about the interventions, populations, study methods and outcomes of significance to the review question and specific objectives. Where reported data are unclear or aggregated, the authors of primary studies will be contacted with requests to provide disaggregated data.
Quantitative data will, where possible, be pooled in statistical meta-analysis using JBI-MAStARI. All results will be subject to double data entry. Effect sizes expressed as odds ratio (for categorical data) and weighted mean differences (for continuous data) and their 95% confidence intervals will be calculated for analysis. A random effects model will be used and heterogeneity will be assessed statistically using the standard Chi-square. If possible, subgroup analysis will also be undertaken to compare population groups with different levels of health literacy. Where statistical pooling is not possible the findings will be presented in narrative form including tables and figures to aid in data presentation where appropriate.
Conflicts of interest
The authors declare that there are no conflicts of interest.
We would like to acknowledge Professor Diane Morin for her contribution to the initial conception of this systematic review.
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Appendix I: Appraisal instruments
MAStARI appraisal instrument
Appendix II: Data extraction instruments
MAStARI data extraction instrument