Abstract: We included 55 studies in the review. Thirty-three studies in 14,174 children provided information for the QCA, and 33 RCTs in 12,623 children measured the effects of interventions. Eleven studies contributed to both the QCA and the analysis of effectiveness. Most studies were conducted in North America in socially disadvantaged populations. High school students were better represented among studies contributing to the QCA than in studies contributing to effectiveness evaluations, which more commonly included younger elementary and junior high school students. The interventions all attempted to improve knowledge of asthma, its triggers, and stressed the importance of regular practitioner review, although there was variation in how they were delivered. QCA results highlighted the importance of an intervention being theory driven, along with the importance of factors such as parent involvement, child satisfaction, and running the intervention outside the child's own time as drivers of successful implementation. Compared with no intervention, school-based self-management interventions probably reduce mean hospitalisations by an average of about 0.16 admissions per child over 12 months (SMD –0.19, 95% CI -0.35 to -0.04; 1873 participants; 6 studies, moderate certainty evidence). They may reduce the number of children who visit EDs from 7.5% to 5.4% over 12 months (OR 0.70, 95% CI 0.53 to 0.92; 3883 participants; 13 studies, low certainty evidence), and probably reduce unplanned visits to hospitals or primary care from 26% to 21% at 6 to 9 months (OR 0.74, 95% CI 0.60 to 0.90; 3490 participants; 5 studies, moderate certainty evidence). Self-management interventions probably reduce the number of days of restricted activity by just under half a day over a two-week period (MD 0.38 days 95% CI -0.41 to -0.18; 1852 participants; 3 studies, moderate certainty evidence). Effects of interventions on school absence are uncertain due to the variation between the results of the studies (MD 0.4 fewer school days missed per year with self-management (-1.25 to 0.45; 4609 participants; 10 studies, low certainty evidence). Evidence is insufficient to show whether the requirement for reliever medications is affected by these interventions (OR 0.52, 95% CI 0.15 to 1.81; 437 participants; 2 studies; very low-certainty evidence). Self-management interventions probably improve children's asthma-related quality of life by a small amount (MD 0.36 units higher on the Paediatric AQLQ(95% CI 0.06 to 0.64; 2587 participants; 7 studies, moderate certainty evidence). School-based asthma self-management interventions probably reduce hospital admission and may slightly reduce ED attendance, although their impact on school attendance could not be measured reliably. They may also reduce the number of days where children experience asthma symptoms, and probably lead to small improvements in asthma-related quality of life. Many of the studies tested the intervention in younger children from socially disadvantaged populations. Interventions that had a theoretical framework, engaged parents and were run outside of children's free time were associated with successful implementation.

Plain-language summary: We included 55 studies. Thirty three of these studies helped us to gain a better understanding of the best way to deliver an asthma self-management intervention. Thirty three studies helped us to determine whether these interventions are successful in improving children's health and well-being. Eleven studies contributed to both. We included 23 studies in quantitative models measuring children's asthma outcomes (an outcome is something you can measure to find out if an intervention worked). Results show that school-based self-management interventions could improve outcomes such as hospitalisations, emergency department visits, and health-related quality of life. Fewer studies reported improved unplanned medical visits or reduced numbers of days on which children could not do their normal activities. Interventions did not reduce school absences, symptoms, or reliever medication use. The more effective interventions were based on theories about how the intervention might work. Researchers found that including parents in the intervention, making sure children were happy with the intervention, and running the intervention during school hours helped increase fidelity. Studies that measured whether an intervention worked were usually well designed; however sometimes they were difficult to carry out, and some may not have measured outcomes accurately. Reviewers found that some of the studies conducted to understand how an intervention should be delivered were at risk of bias, and certainty of the evidence was generally lower for these studies. Evidence suggests that school-based self-management interventions can help children with asthma and can reduce hospital admissions and trips to the emergency department. Study findings suggest that interventions that were based on a theory about how an intervention can be planned and delivered could prove useful in improving children's outcomes, reaching large numbers of children, and keeping dropout rates low, and indicate that those designing interventions should consider factors such as including parents. This review is current to August 2017.