Background

Globally, the burden and threat of non-communicable diseases (NCDs) remain one of the major challenges of public health in the twenty-first century [1,2,3,4]. NCDs are chronic diseases or conditions that tend to have a long duration due to a combination of genetic, physiological, environmental and behavioural factors [5]. NCDs including heart disease, stroke, cancer, diabetes and chronic lung disease is ranked first among the causes of deaths and collectively responsible for over 71% of all deaths globally [5, 6]. Approximately two thirds of all NCD deaths and 82% of the 16 million people who died prematurely, or before reaching the age of 70 years, occur in low- and middle-income countries (LMICs) [5]. There is also a greater risk of premature death from NCDs in the WHO African region (22%) compared to the regions of the Americas (15%), European (17%) and the Western Pacific (16%) regions [4].

Worldwide, mortality due to NCDs is projected to reach 52 million by 2030 with 27% in the Africa region with the highest mortality occurring in sub-Saharan Africa (SSA) [7]. Moreover, deaths due to NCDs among populations between the ages of 10 and 60 years are predominant in SSA [8, 9], and also, there has been a substantial increase (67.0%) in disability-adjusted life years (DALYs) due to NCDs in SSA from 90.6 million in 1990 to 151.3 million in 2017 [10, 11].

The rising burden of NCDs in SSA is partially due to weak healthcare systems, resource constraints, low investment, limited infrastructure and capacity, combined with the already overwhelming burden of communicable, maternal, neonatal and nutritional (CMNN) diseases as well as low political commitment [6, 12, 13], Given this, there has been increased global advocacy to prioritise and address the growing burden of NCDs in SSA [14]. These culminated into the United Nations General Assembly declarations in 2011 (resolution A/RES/66/2), 2014 (A/RES/68/300) and 2018 (A/RES/73/2) to strengthen global and national responses to prevent and control NCDs [1, 15, 16]. Then, the WHO in 2017 recommended a set of interventions referred to as ‘Best buys’ which are considered cost-effective, affordable, feasible and evidence-based for implementation particularly in LMICs [17].

The ‘best buys’ are measures to reduce the four common risk factors of NCDs including tobacco use, unhealthy diet, physical inactivity and harmful use of alcohol in four disease areas of cardiovascular, diabetes, cancer and chronic respiratory diseases [2, 17]. Knowledge on the extent of adoption and implementation of the WHO ‘best buys’ is unknown, particularly in SSA, yet no previous scoping review has been previously conducted to examine the range of evidence and identify research gaps.

A scoping review is considered useful in mapping key concepts underpinning a research area, examining and clarifying broad areas to identify gaps in the evidence and reporting on the types of evidence that address and inform policy and practice in an area of study [18]. A scoping methodology is also considered a useful approach for preliminary mapping of evidence that will form the basis for determining the value of undertaking a full systematic review [18]. Therefore, we will conduct a scoping review to systematically map and describe research evidence on implementation of the WHO ‘best buys’ and other interventions for prevention and control of NCDs focusing on ‘unhealthy diet’ (Table 1) in SSA. We hope the results of this study will facilitate a better understanding of the practical application of the ‘best buys’ and other interventions to reduce the risk of NCDs and reveal knowledge gaps for future research in SSA. Moreover, this review may influence further research to inform policy as well as implementation research which may collectively contribute towards the attainment of the WHO 25 by 25 target and the Sustainable Development Goal target 3.4 which aims at reducing by 25% and one-third, the risk of premature mortality from non-communicable diseases by 2025 and 2030 respectively [2, 19, 20].

Table 1 WHO best buys and other recommended interventions for unhealthy diet
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Methods

This protocol was developing following the preferred reporting items for systematic reviews and meta-analysis extension for protocols (PRISMA-P) (Supplementary file 1). This scoping review will be conducted in keeping with Arksey and O’Malley’s methodological framework (identifying the research question; identifying relevant studies; study selection; charting the data; and collating, summarising and reporting results) [18], bearing in mind Levac et. al. recommendations [21] and the Joanna Briggs Institute checklist for scoping reviews [22].

Identifying the research question

The main research question is as follows: for NCDs due to unhealthy diet such as type-2 diabetes, cardiovascular diseases, high cholesterol and some cancers, what research evidence exists on the adoption and implementation of the WHO’s ‘best buys’ and other interventions for their prevention and control in SSA since 2017 to date? Table 2 illustrates this review population, concept and context as part of the eligibility criteria. This scoping review sub-questions will be:

  • What evidence exists on the implementation of the ‘best buys’ and other interventions to reduce the risk of NCDs due to unhealthy diets in SSA?

  • What evidence exists on the barriers/challenges of implementing the ‘best buys’ and other interventions to reduce the risk of NCDs due to an unhealthy diet in SSA?

Table 2 PCC framework for defining the eligibility of the studies for the primary research question
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Identifying relevant studies

The ‘best buys’ and other interventions for the prevention and control of NCDs were endorsed by the Seventieth World Health Assembly in May 2017. Given this, a thorough search for relevant published/grey literature will be conducted in PubMed, Google Scholar, SCOPUS, EBSCOhost (CINAHL, Health Resource, and PsycINFO), and Cochrane Library from June 2017 onwards to the search date. The World Health Organization and Governments/Ministries of Health websites will also be searched for relevant evidence sources. Moreover, the reference list of the included studies will be manually searched for relevant studies/grey literature. A comprehensive search strategy will be developed in consultation with an experienced librarian using a combination of the following keywords: ‘implementation’, ‘non-communicable diseases’, ‘chronic diseases’, ‘best buys’, ‘cost-effective, affordable and evidence-based interventions’, ‘salt intake’ food legislation’, ‘food labelling’, ‘fruits and vegetables’, ‘other interventions’, ‘prevention’, ‘control’, ‘unhealthy diet’, ‘sub-Saharan Africa’ and ‘all countries in the WHO Africa Region’. Boolean terms, ‘AND’ and ‘OR’, will be used to separate keywords. Medical Subject Heading (MeSH) terms and subject heading will be included where essential during the electronic database search. Study designs will be limited to primary studies and policy documents, and date (from June 2017 to 2021), but not language. Each search will be documented appropriately (Table 3), and Mendeley Desktop version 1.19.8 was used to compile and manage all references. The principal investigator (AK) will conduct the search, but a second reviewer will double-check for completeness.

Table 3 Pilot search in PubMed electronic database
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Study selection

Following deduplication of titles from the Mendeley desktop library created for this review, a screening tool will be developed using this study’s inclusion criteria in Google forms. The Google form will be shared with two members of the review team for pre-testing with a random sample of 10 titles and abstracts. The Google form will be amended if needed and, subsequently, use electronically for the study selection. The title and abstract screening (stage 1) will be performed by two reviewers (AK and MAM) independently guided by the inclusion and exclusion criteria. Then, the full text articles will be compiled and again screened (stage 2) by AK and MAM independently using the review eligibility criteria as a guide. A third reviewer will be consulted to resolve any discrepancies at both stages. The Catholic University library will be contacted to provide assistance in cases where a full article is inaccessible from the database or request will be made directly to authors of such articles via email for the full article. At least, the reviewers will make two attempts to reach the authors for full text articles if not found using other sources. The Preferred Reporting Items for Systematic Reviews and Meta-analysis (PRISMA) flow diagram [24] will be adopted to present the screening results of the study, as shown in Fig. 1.

Fig. 1
figure 1

PRISMA 2009 flow diagram

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Charting the data

A data charting form will be designed for the extraction of all relevant data from the included studies. The form will contain the following headings: author(s) and year of publication, study title, objective/aim of the study, study design, country (study location), study setting (school, health facility, community, or others), study population, intervention(s), study results and ‘key findings relating to the implementation of the intervention for unhealthy diet’. To ensure the accuracy of the data extraction form, it will be pretested by two independent reviewers (AK and MAM) using a couple of the included studies and amended appropriately. AK will perform the data extraction, but two members of the review team will independently double-check the results extracted for completeness. The authors of the included evidence sources/studies will also be contacted to verify the results extracted.

Collating, summarising, and reporting the results

Content thematic analysis approach [25] will be used to identify relevant themes and sub-themes to answer the review questions. The emerging themes will be structured around the four domains: effective interventions with cost-effectiveness analysis (CEA) less than or equivalent to hundred US dollars per DALYs averted in LMICs, effective interventions with CEA greater than hundred US dollars per DALYs averted in LMICs, other recommended interventions for the prevention and control of NCDs and barriers/challenges of implementing the ‘best buys’ and other interventions. The barriers/challenges will be identified using thematic content analysis. A qualitative approach will be used to report summaries of emerging key findings. Where appropriate, tables and figures will be used to represent this review’s findings, but tables and figures will also be used where possible. The Preferred Reporting Items for Systematic Reviews and Meta-analysis: Extension for Scoping Review (PRISMA-ScR) checklist will be followed to report this study.

Discussion

This scoping review aims to identify and describe research evidence on the adoption and implementation of WHO ‘best buys’ and other interventions for the prevention and control of NCDs that relate to unhealthy diets in SSA. The review will have relevance to a variety of audiences including researchers, policymakers, NCD units and managers of various countries in SSA, donors and other interested bodies in understanding the extent of implementation of these ‘best buys’, as well as the barriers to implementation in SSA. Policymakers will also use this research for reflection and as a form of feedback on the progress of implementation of ‘best buys’ and other interventions for reducing the risk of NCDs due to unhealthy diet in SSA.

Evidence from WHO CEA demonstrates that investing in the implementation of the WHO ‘best buys’ and other interventions for NCDs prevention and control will not only improve health outcomes and save lives but can also improve a country’s economic productivity [13]. It is anticipated that the results of the proposed study will inform future research and reveal evidence-based information to address potential issues that may arise from implementation of the ‘best buys’ and other interventions for unhealthy diet in SSA. The proposed study will thus contribute to addressing implementation gaps, strengthen health systems and improve resource allocation as well as improve research in implementing the ‘best buys’ and other interventions to reduce NCDs in SSA.

Although there are four common risk factors of NCDs [2], due to resource and time constraints, this review will exclude evidence, policies and interventions relating to risk factors of tobacco use, physical inactivity and harmful use of alcohol.

Therefore, the results produced by this review will help identify implementation and policy gaps to inform future implementation research/interventions studies using a variety of evidence-based strategies towards the prevention and control of NCDs due to unhealthy diets in SSA.