We used the Preferred Reporting Items for Systematic Review and Meta-Analysis Protocols (PRISMA-P) statement to develop this protocol (43). (Additional file 1: PRISMA-P checklist). We will use the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) for reporting of the systematic review (44). A research protocol (registration ID-180545) has been registered in the International Prospective Register of Systematic Reviews (PROSPERO) and the study protocol registration number is: CRD42020180545.
We will conduct a systematic mixed study review because it entails the synthesis of data from studies with diverse designs, including qualitative, quantitative, and mixed methods studies (45, 46). By systematically assessing evidence from diverse designs, this review provides an up-to-date summary of the state of research knowledge on a healthcare topic.
Study eligibility criteria
Following the PICO (population/problem, intervention, comparison, and outcome) for this review, the population “older adults with DSI” is defined as an individual aged 65 years and over with a condition that combines varying degrees of both hearing and visual impairment (47). The review will include studies on older adults with DSI from the following three distinct groups: Group 1 (older adults with pre-lingual deafblindness), Group 2 (older adults with post-lingual deafblindness–those who acquire both types of impairment during their lives or those with single sensory impairment [vision or hearing] by birth and then subsequently acquire another [vision or hearing] impairment), and Group 3 (older adults with dual sensory loss of vision and hearing due to age-related changes). The intervention is any strategy used by care providers that improves the experiences of access and utilization of healthcare by older adults with DSI in relation to meeting their healthcare or rehabilitation needs, including screening, assessment, and interventions. There are no comparisons/controls, while the outcomes are strategies and tools used by care providers that promote continuity of care for older adults with DSI. The focus is on equitable access to quality care that is seamless along the continuum of care from the screening of the DSI condition to receiving individual specialized health and rehabilitation interventions.
Consistent with the systematic review process, post hoc inclusion criteria are developed by the research team to assess the relevance of articles identified in the search process. Studies will be included if (1) they are original research studies of any study design, including randomized controlled trials, observational, descriptive, or cohort studies, case-control studies, cross-sectional studies, qualitative studies, and mixed methods studies, (2) all or some participants are older adults (age 65 years and above), and (3) participants had a concurrent hearing and vision impairment/DSI (defined subjectively through self-report or objectively using standardized screening or assessment tests for hearing and vision impairment). Studies were excluded if (1) they were prevalence or incidence studies, (2) they included only children (0-18 years) or working-age adults (18-64 years) with DSI, or (3) they are on sensory impairment in other senses, e.g., such as smell, gustatory, etc., or single sensory impairments (such as hearing or vision impairment only). Editorials, conference publications, thesis/dissertations, books or letters will not be included.
Information sources and search strategy
Database search strategies were developed by the research team in ongoing consultation with a senior health science librarian (PD) from the Université de Montréal. Dupont is one of the research team members and has over 25 years of experience in performing bibliographic and patent information searches, including systematic reviews over the last 10 years. A comprehensive literature search of eight databases (Cochrane Database of Systematic Reviews (from inception), CINAHL (1937-) via EBSCOhost, MEDLINE (1946-), EMBASE (1974-) via Ovid, Global Health (1973-), PsycINFO (1967-) via APA PsychNet, and Web of Science (1945-) will be performed in accordance with the Preferred Reporting Items for Systematic Reviews (44). To supplement our electronic search, we will search clinical trials registries such as www.ClinicalTrials.gov, BioMed Central ISRCTN registry (https://www.isrctn.com/), and International Clinical Trials Registry Platform (ICTRP) (http://www.who.int/trialsearch/). In addition, we will hand-search reference lists from selected studies to identify any additional studies not captured by our literature search. There will be no language and date restrictions. See Table 1 for an example of a search strategy used in Medline (as of June 26, 2020). The final search strategies adopted for all searched databases will be made available in the systematic review article.
Study Selection
Using PRISMA guidelines, a two-stage screening process will be used to assess the relevance of studies – first, at the level of title and abstract screening, second, at the level of full-text review. EndNote Versions X9 (Clarivate Analytics, PA, USA) will be used to manage references and remove duplicates, while screening of articles will be accomplished using Covidence (Veritas Health Innovation, Melbourne, Australia). Based on the following post-hoc inclusion criteria, the two reviewers (AJ & SG) will independently screen identified studies by titles/abstracts and classify them into three categories – ‘Yes,’ ‘Maybe’ and ‘No’ in Covidence. To ensure inter-rater reliability amongst reviewers, a pilot test of screening of 100 citations will be conducted prior to the screening of retrieved sources, and inter-rater reliability will be assessed. For articles in languages other than English, articles will be first translated using DeepL (a language translation software) and screened by (AJ & SG).
Following title and abstract screening, a full-text review of selected studies will be conducted independently by two reviewers (AJ & SG). The fourth reviewer (WW) (faculty member with expertise in DSI research and reviews) will be consulted to resolve conflicts in the selection of articles at the title/abstract level screening as well as at the level of full-text review. Articles will be selected for full-text review if they focused on older adults with DSI and discussed strategies/tools that improves their healthcare access and utilization in some way. Studies that do not meet the criteria will be excluded, and reasons for their exclusion will be documented in Covidence using study tags. The reference lists from included studies will be hand-searched for additional articles for inclusion. Finally, search results will be summarized using a PRISMA flow diagram (http://www.prisma-statement.org/PRISMAStatement/FlowDiagram).
Risk of bias, assessment of methodological quality, and data extraction
Two reviewers (AJ & SG) will independently conduct the critical appraisal of the methodological quality of the included articles using the Mixed Methods Appraisal Tool (MMAT). The MMAT is designed for the appraisal stage of systematic mixed studies reviews, i.e., reviews that include qualitative research, randomized controlled trials, non-randomized studies, quantitative descriptive studies, and mixed methods studies (48). This tool is chosen for this review as it is freely available, used in public health science and can accommodate studies of diverse designs. Each study will be assigned a quality score using MMAT.
Data extracted from each included study will comprise the following: author(s), year of study, location of study, stage of research, study design, study population, sample size, older adult definition/age range, sensory impairment definition, aim/focus of article, methods, interventions, key outcome/strategies, bias assessment and any other data significant to the systematic review research question. Any differences that arise in judgement will be resolved through discussion, or the consensus will be reached by discussion with the fourth reviewer (WW). Authors of some highly relevant studies may be contacted for additional information pertinent to the systematic review research and will be given two weeks to respond.
Data synthesis
Based on the study design (quantitative, qualitative, mixed methods), we will group and analyze the data separately, using statistical analysis for quantitative data and thematic analysis for qualitative data (49). We will use narrative (descriptive) synthesis as a primary strategy for data synthesis. Summary measures are reported, including odds ratios, linear regression coefficients, and correlation coefficients, and meta-analysis will be conducted, if the data allow. We will apply the PRISMA equity framework for critical reflection and interpretation of the cumulative evidence. We will report data in the form of tables of study characteristics, participants' details, outcomes, results, and authors' conclusions. While all team members will be involved in the process of interpretation and synthesis, the main reviewer (AJ) will produce the written review. We will provide recommendations taking account of all the qualitative and quantitative findings.
Knowledge translation
An integrated knowledge translation approach is used in collaboration with our partner organizations in Quebec and Ontario, Canada, to prioritize the research focus in this systematic review. We will engage in a consultation exercise with clinical and research experts in hearing, vision, and dual sensory impairment in Quebec and Ontario to discuss the findings of the review on emergent and existing strategies. To ensure dissemination of our review findings with partners and stakeholders, we will publish the review in a reputed health science journal. We will also design and share an infographic or research brief for older adults with DSI and their care providers. We will finally employ the communication materials of our community partners to share the findings.