Aims of the Review
We aim to address the following points through the review of school-based interventions focusing on the DBM, and educational outcomes of adolescents in LMICs.
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Characterize the interventions that have been carried out
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Ascertain the effectiveness of these interventions in addressing specific outcomes of interest
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Identify factors that contribute to the success or failure of the interventions, including the potential barriers to their successful implementation in the context of LMICs
Eligibility criteria
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We will include randomized controlled trials, with the intervention randomized to individuals or in clusters (including classes, schools, and groups/clubs). We will also include controlled before-after studies as they are non-randomized studies with a relatively rigorous design and occupy a non-negligible proportion of the relevant literature. Non-randomized controlled trials will also be eligible for inclusion as long as the baseline differences between study arms are accounted for in the analysis.
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Studies involving adolescents (boys and girls) aged 10 to 19 years.
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Studies conducted in LMICs—as defined by the World Bank in the year 2020 [31].
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Studies involving interventions for one or more of the following: interventions to promote healthy diets, interventions promoting physical activity, nutrition education, school feeding, micronutrient supplementation, managing acute nutrition problems, prevention, and management of overweight, obesity, or anemia, school gardens, and access to safe environment and hygiene including WASH interventions.
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Studies addressing the following outcomes:
For DBM: Change in nutritional status measured by anthropometry (e.g., physical activity, height-for-age z scores, weight-for-age z scores, weight-for-height z scores, skin-fold thickness measures, stunting, underweight, wasting, body mass index, overweight, obesity, waist-to-height ratio, and central obesity), and knowledge of and practices related to diet.
For educational difficulties: school enrolment, school completion, school attendance, prevention of school absenteeism and/or drop-out, and cognitive, maths, and/or language skills
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The control (comparison) in each included study can be participants who did not receive any intervention or received general health education intervention.
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We will include published articles and ongoing studies for which preliminary findings are available.
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We will not place any restrictions in terms of the year of publication, language, sample size of the study, or duration of the intervention provided.
Exclusion criteria
We will not consider the following studies:
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Non-randomized controlled trials that did not account for the baseline differences between the study arms;
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Studies without a proper control (comparison) group/arm; e.g., uncontrolled before-after studies,
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Observational studies including cohort, case-control, and cross-sectional designs,
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Editorial commentaries, opinions, and review articles,
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Clinical treatments/interventions targeted towards individuals with specific medical conditions such as programs intended for underweight, overweight, or obese adolescents,
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Studies describing nutrition and/or educational interventions without linkage to specific outcome/s, and
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Studies of educational interventions focusing only on educational outcomes (e.g., school or classroom participation, classroom environment, teacher performance, and so on).
Information sources
The following principal sources of electronic reference libraries will be searched: Medline (through PubMed), Embase, CENTRAL (through the Cochrane Library), CINAHL (Cumulative Index to Nursing and Allied Health Literature), and Google Scholar. All databases will be searched for eligible studies from the inception of each database through September 2020. Detailed examination of cross-references and bibliographies of available publications to identify additional sources of information will also be performed. This search of studies will be supplemented by reviewing organizational websites such as the World Food Programme, World Bank, Food and Agriculture Organization, United Nations Children’s Fund, and United Nations Population Fund. Articles written in languages other than English will be translated by colleagues who are native speakers, whenever possible. Studies that cannot be adequately translated will be excluded.
Search strategy
Guided by the conceptual framework, a broad search strategy (e.g. type of study [randomized controlled trial OR controlled before-after studies OR quasi-experimental studies] AND intervention domain [nutrition] AND population [adolescents] AND setting [low- and middle-income countries]) will be performed in PubMed without time restrictions. We consulted with a health science librarian to develop the PubMed search strategy, which is provided in Additional File 1. The sensitivity of the search strategy will be examined by confirming that several sentinel articles are identified. The PubMed strategy will be adapted to the syntax appropriate for other databases. The following details will be documented for each search: databases searched, date of search conducted on, search strategy (i.e., subject headings and keywords used, including whether terms are exploded, truncated and how terms are combined), years searched, filters used, number of results retrieved for each search, the total number of records, duplicates identified, and numbers pre- and post-screening. Also, all publications identified through hand searching will be noted with a source (i.e., name of journal/website, conference proceedings, etc.) and the years.
Data Management
EndNote X9 (Clarivate Analytics, PA, USA) will be used to store the records retrieved from searches of electronic databases. The records will also be imported into Covidence (Veritas Health Innovation, Melbourne, Australia), an internet-based program that facilitates the streamlined management of the systematic review. Duplicate records will be detected and removed first by EndNote and then by Covidence.
Two reviewers will independently assess the search results based on the inclusion and exclusion criteria. First, all searched titles and abstracts will be reviewed to exclude irrelevant studies. Disagreements between the two reviewers will be resolved by discussion or by a third reviewer, if necessary.
The interrater agreement will be quantified by calculating the raw percentage of agreement and Cohen's \(\kappa\) coefficient. A study flow diagram will be maintained as recommended by the PRISMA statement (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) [32], with the specific reasons for excluding studies. Neither of the reviewers will be blind to journal titles or the names of the authors.
Data extraction
Two reviewers will independently extract and enter the data of studies included in the review. A data extraction form provided as Additional File 2, will be developed and then pilot-tested on five randomly selected studies. The following information will be extracted for each selected study: title, authors (first author and corresponding author), contact information of corresponding author, journal (or source for reports), year of publication, year of intervention implementation, country and geographical setting, study design, sample size (if a cluster randomised trial, number of clusters and average cluster size), sample characteristics (e.g., age, sex, and socioeconomic status of the participants), intervention (including duration, intervention type, guiding theory/framework, intervention description, delivery mechanisms and agents, and procedures employed for selection, training and supervision of delivery agents, intervention coverage and fidelity information, and challenges and barriers encountered in intervention delivery), measure of adherence, information on control/comparison intervention, outcomes assessed, time-points, main findings with point estimates and measures of variance (standard errors, 95% CI and/or p-values), and reasons provided for success/failure. Multiple reports of a single study will be collated as additional results may be provided in different reports. In case of missing information or inconsistent results across reports of a single study, we will contact the corresponding author via email to obtain more accurate results or additional information. A maximum of two contact attempts will be made.
Quality assessment
For the assessment of the risk of bias of the selected studies, we will use the Cochrane Collaboration’s tool for assessing the risk of bias in randomized trials [33, 34]. Two reviewers will independently evaluate methodological quality. Any uncertainties or disagreements will be resolved by discussion or by a third reviewer, whenever needed. The tool is a domain-based evaluation, in which critical assessments will be made separately for the bias arising from the randomization process, the bias due to deviation from intended interventions, the bias due to missing outcome data, the bias in the measurement of the outcome, and selective outcome reporting. The judgment for each entry will involve assessing the risk of bias as “low risk,” as “high risk,” or as “some concerns,” with the last category indicating either lack of information or uncertainty about the potential for bias.
We will use the Risk of Bias in Non-randomized Studies of Interventions (ROBINS-I) tool [35], to assess the risk of bias for controlled before-after studies and non-randomized controlled trials. This tool considers biases from confounding, the bias in selection of participants into the study, the bias in classification of interventions, bias due to deviations from intended interventions, the bias due to missing data, the bias in the measurement of outcomes, and the bias in selection of the reported results. Each domain will be judged as “low risk of bias,” “moderate risk of bias,” “serious risk of bias,” “critical risk of bias,” or “no information.” Based on the domain-specific judgments, we will consider a non-randomized study (a) at low risk of bias if it is judged to have a low or moderate risk of bias for all domains; or (b) at high risk of bias if it is judged to have a serious or critical risk of bias in one or more domains; or (c) have some concerns if the assessment is unclear for one or more domains but low or moderate for all other domains. We will contact the corresponding authors of the reports to obtain more information, when necessary. We will summarize the results of the assessment of the risk of bias in a table, in which the judgment for each domain will be presented with a justification.
Synthesis of evidence
A systematic and narrative synthesis of all included studies will be presented in the text as well as in a table. Based on our conceptual framework, the interventions will be identified by an iterative process of data collating and key findings will be broken down into specific categories, derived from the articles. We will not conduct the meta-analyses given the considerable heterogeneity of both the interventions and outcomes.
We will follow the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) checklist and guidelines to ensure a robust and replicable process [36]. Effect estimates for continuous outcomes will be expressed as mean differences (with 95% CI) comparing the intervention group with the control group; effect estimates for dichotomous outcomes will be expressed as risk ratios, rate ratios, hazard ratios, or odds ratios (all with 95% CI), comparing the intervention group with the control group.
Registration and reporting
This protocol is submitted for registration with the International Prospective Register of Systematic Reviews (PROSPERO) on September, 24 2020 (ID 211109). In the event of protocol amendments, the date of each amendment will be accompanied by a description of each change and the rationale on PROSPERO.
This protocol is written following the Preferred Reporting Items for Systematic Review and Meta-Analysis Protocols (PRISMA-P) [36]. The PRISMA-P checklist can be obtained from Additional File 3. We will report this systematic review following the Cochrane Handbook for Systematic Reviews of Interventions [37] and the PRISMA guidelines [32, 36].