We will conduct a systematic review, identifying population-based quantitative and qualitative studies that will help to investigate determinants of substance use among adolescents in Africa. A comprehensive search of relevant electronic databases (The Cochrane Library, PubMed/Medline, EMBASE, African Journals Online, Google Scholar, Scopus, Global Health, PsychINFO, Science Direct, and the World Health Organization (WHO) African Index Medicus (AIM) regional database) for studies published between 1 January 2000 and 31 December 2019 will be conducted. This period was selected to cover the millennium years (2000–2019) in the hope to capture the indicated rise in substance use among this target population. Online journals will also be searched, and reference lists of identified reports will be manually reviewed. Broadly search terms that will be used alone or in combination to find relevant studies or reports are outlined in Table 1.
Inclusion & exclusion criteria
The main outcome of this review will be to characterise key determinants that have been found to significantly influence any substance use among adolescents in Africa. All original studies conducted in Africa that report on determinants of substance use (alcohol consumption, cigarette smoking or tobacco consumption, or other illicit drugs) or factors will be included. Papers reporting study participants aged between 10 and 19 years will be included. No papers will be excluded based on language, but we envisage most studies in this region to have been published in English or French. Studies will not be excluded on based on study design.
Non-human studies, studies without clearly defined study designs, studies available only as abstract with unclear outcomes, methodologies for substance use, and review articles will be excluded. Studies rated as weak or low based on the evaluation criteria of quality assessment tools used will be excluded.
The methodological quality of each study will be evaluated independently by two reviewers (SJ & TM). The tool developed by the Effective Public Health Practice Project will be used to assess quality for quantitative studies . This tool has been chosen because of its ability to extensively assess methodological quality and its usability across different quantitative research designs. The tool will consider aspects like the presence of selection bias and confounders, study design, blinding, data collection methods, withdrawals and drop-outs and the appropriateness of the study’s analysis to the research question [16, 17]. Quality of qualitative studies will be assessed using the Critical Appraisal Skills Programme (CASP) developed by the Public Health Resource Unit, National Health Service, England . The CASP includes 10 questions to assess rigorousness, credibility and, relevance of the qualitative study by answering yes/no for each question. The first two questions are general screening questions that consider clarity of the study goal, and whether the study methodology is appropriate. When both questions are positively answered, reviewers proceed to the remaining questions to consider methodological quality .
The two reviewers will independently assess articles prior to inclusion in the final review using these checklists. Studies will be graded using these tools to assess quality of study design and reporting including information about how substance use determinants are measured and operationalised. Discrepancies in the reviewers’ evaluations will be discussed until consensus is reached. Any disagreement that arises between the reviewers’ ratings will be solved by involving a third reviewer.
Data abstraction and synthesis
Two reviewers (UK and IM) will independently go through resultant studies from the database searches, remove studies that do not meet the inclusion criteria, then merged and de-duplicate the lists of eligible studies. After undergoing the quality assessment process, data from each eligible article will be extracted by the reviewers (ND, UK and IM) onto a data extraction sheet. This sheet will include the following information; author(s) and publication date, study setting, research focus, study design, sample size, participants’ age mean/range, substance type (e.g. alcohol, tobacco), determinants (reported factors associated with substance use) and key findings.
Research findings will be pooled using the data extraction sheet. This will involve aggregation or synthesis of findings to generate a set of statements that represent that aggregation, through assembling the findings rated according to their quality, and categorizing these findings on the basis of similarity in meaning. These categories will then be subjected to a meta-synthesis in order to produce a single comprehensive set of synthesized findings that can be used as a basis for evidence-based practice. Where textual pooling is not possible the findings will be presented in narrative form.
The review team will meet frequently (every two weeks) to discuss any inconsistencies in data extraction process. The PRISMA guideline will be used for reporting during the systematic review. Table 2 outlines the review timescales.