This protocol was developed in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analysis Protocols (PRISMA-P) 2015 checklist and the Joanna Briggs Institute Reviewers Manual—Chapter 7: Systematic reviews of etiology and risk.24,25 This protocol has been registered in the International Prospective Register of Systematic Reviews (PROSPERO) under study protocol registration CRD 42019124740.
Objectives
The primary objective of this review is to evaluate whether adolescents’ exposure to a higher degree of community violence is associated with a higher risk of internalizing mental health symptoms.
The secondary objective is to investigate whether different degrees of community violence (victimization, witnesses and heard about) is associated with a higher risk of different types of internalizing mental health symptoms (depression, posttraumatic stress disorder, and anxiety).
Search strategy
The search terms were based on the question in the PEO format and were constructed with a librarian. The main concepts were as follows: “adolescents” OR “youth” OR “teenagers” AND “community violence” OR “urban violence” OR “neighborhood violence” AND “mental health” OR “anxiety” OR “depression” OR “posttraumatic” OR “substance abuse” OR “aggression” OR “internalizing” OR “externalizing” OR “psychological symptoms”. The complete path of the search structure is available in appendix one. We added a filter for human research and types of studies only, no filters for year of publication were applied. Studies from all languages will be included. The lists of references in the included studies will be examined to verify whether other studies can fit the spectrum of the systematic review and could not be identified in the structured search. A librarian will work on obtaining the full-text works and seeking in the bibliographic bases, libraries and contact authors.
The first search was conducted on March 9th, 2019. It had the third field encompassing externalyzing and internalyzing symptons besides learning disabilities. The search was updated on January 14th, 2021. At this time, it included only internalyzing symptons and a new filter were applied for year of publication (2019 to 2021). Due to this characteristics, the second search, naturally, yield less results.
Information sources
We started the search in six allied health research databases: Medline accessed through PubMed, PsycINFO, Embase, LILACS, Web of Science and Scopus. Regarding gray literature, only those corresponding to theses and dissertations will be included; these will be identified in the databases above, and the platform ProQuest Dissertation and Theses will be used to search for full texts. Conference abstracts and lectures will be excluded.
Study selection
Data selection will be operation operationalized in Mendeley and carried out in three stages: (i) title, (ii) abstract, and (iii) full texts. For each study, a critical reading of each work will be performed independently by two researchers, according to the pre-established inclusion and exclusion criteria. All steps will be preceded by a pilot when the research team will analyze and discuss 10% of the total number of works of each phase. The concordance between researchers in the pilot study will be acceptable if it is larger than 75%. In the first and second stages of selection (title and abstracts), disagreements do not need to be resolved, and the studies can be included. In the third stage (full-text reading), the discordances will be discussed between two researchers, and when it is not possible to resolve them, a third researcher will be called. Alternating pairs of researchers will be programmed to avoid selection bias. The reasons for the exclusion of the papers will be recorded individually by each researcher.
When necessary, the authors will be contacted for further clarification. Since we will exclude studies that consider school violence and sexual violence in the construct of community violence, it will be necessary to determine whether all included studies did not contain questions related to school and sexual violence, or if they contained these questions, whether they were analyzed separately.
Data extraction
A standardized prepiloted formulary will be used to extract data from the included studies for the assessment of study quality and evidence synthesis. Extracted information will include the following: study setting; study population; participant demographics; details of the exposure of interest and comparable group; study methodology; recruitment and study completion rates; outcomes; and times of measurement. Two review researchers will work on this phase independently, and when discrepancies are identified, they will resolve them through discussion or consultation with a third author. The study authors will be contacted in cases of missing data. Extraction will be operationalized in Epidata 3.1.
Assessment of methodological quality
The quality of the studies will be evaluated independently by two researchers through a predefined quality assessment form for cohort/case-control studies and descriptive studies published in the Joanna Briggs Institute Reviewers’ Manual.28
Data synthesis
We will provide a narrative synthesis of the findings from the included studies, target population characteristics, categories of degree of exposition (victimization, witnesses and heard about) and subtypes of outcomes (depression, anxiety and PTSD). We will also provide summaries of association measures for each study. A flowchart indicating the number of studies identified in each phase and the causes of exclusion will be presented.
If possible, we will pool the results using a random-effects meta-analysis with risk ratios for outcomes, and we will calculate 95% confidence intervals and two-sided P-values for each outcome. Heterogeneity between the studies in effect measures will be assessed using both the Q2 test and the I² statistics. We will consider an I² value greater than 60% to be indicative of substantial heterogeneity. We will conduct sensitivity analyses based on study quality.
We will stratify meta-analyses to explore heterogeneity in effect estimates. If the necessary data are available, subgroup analyses will be performed for degree of exposition (victimization, witnesses and heard about), age, sex and race, as the scientific literature points to a probable modification of effect in these four categories. Age will be divided into the following categories as per the WHO classification: 10-14 years (preadolescence), 15-19 years (adolescence) and 20-24 years (youth). Sex will be divided into male and female. Types of violence will be divided into being victimized, witnessing and hearing about; ethnicity will be categorized into black, white and other.
We will use meta-regression to analyze whether the characteristics above influence the outcome in a statistically significant way. If heterogeneity is not present, publication bias will be assessed using funnel plots. In addition, we will use the approach presented by Begg and Mazumdar.29
Assessing certainty in the findings
The Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA-P) checklist30 and Grading of Recommendations Assessment, Development and Evaluation (GRADE)31 system will be used for grading the certainty of evidence.