School bullying: A systematic review of contextual-level risk factors in observational studies

• Contextual-level characteristics are important in comprehension of school bullying.
• At school-, class- and country-level income inequalities were associated with bullying.
• Several aspects of a better school climate were associated negatively with bullying.
• Methodological differences were substantial limiting the comparison across studies.
• Research should be developed, standardized and include low–middle-income countries.

The present review identified observational studies of contextual-level factors associated with school bullying. Studies that evaluated school bullying and at least one contextual-level variable were eligible. MEDLINE, PsychInfo, Web of Knowledge, and SciELO were searched using the terms: “school bullying” or “school bully” and “risk factor,” “associated factor,” “epidemiologic factor,” “contextual factor,” “social environment,” “school climate” and “school context.” Study titles and abstracts were analyzed by two reviewers. Studies of interest were read in their entirety and relevant information was extracted. The bibliographic search identified 1470 articles, of which 31 met the inclusion criteria. Most studies were conducted in high-income countries and differences in study methods were substantial. At the school- and class-level, contexts with more inequalities in income were associated with increased risk of bullying. Results related to class and school size, and location of school were inconclusive; schools without anti-bullying norms, with inferior teacher support, and with poor class management were at increased risk of bullying. At the city and country-levels, inequalities in income and violence were associated positively with bullying. Research addressing contextual-level variables and bullying should be developed, standardized, and include low- and middle-income countries to understand the role of context in these settings.