The role of vitamin D in the severity and control of asthma in children and adolescents: A protocol for systematic review and meta-analysis

Vitamin D plays an important role in the immune system and consequently in the inflammatory process of asthma. It acts directly on the regulation of helper T lymphocytes 1 (Th1) and helper T lymphocytes 2 (Th2) cells, and regulatory T lymphocytes. Evidence shows that vitamin D acts on dendritic cells, raising inflammatory mediators and increasing the imbalance between Th1, Th2, and helper T lymphocytes 17 (Th17). Evidence shows a strong association between vitamin D levels and asthma incidence, especially in patients with severe and uncontrolled asthma. METHODS: A systematic and comprehensive search will be performed using four main databases, PubMed, EMBASE, Cochrane Library, and Web of Science. Articles will be searched from the earliest available time to august 2022. The studied population will be composed of children and or adolescents with asthma. From the data obtained, all articles found will be transferred to the Rayyan platform. Study selection will follow the Preferred Reporting Items for Systematic Reviews and Meta-Analysis Checklist (PRISMA P-2020). In addition, if sufficient data are available, a meta-analysis will be conducted. Two independent reviewers will conduct the studies selection, data extraction, and risk of bias assessment. The outcome measures will be to analyze the serum levels of vitamin D in patients with asthma and to relate this hormone to the control and severity of the disease and its anti- inflammatory effect. RESULTS: A systematic review will provide better knowledge regarding vitamin D and its role in the severity and control of asthma. CONCLUSIONS: The findings of this study will be published in a peer-reviewed journal.