Nutritional supplementation of vitamin A and health-related outcomes in patients with multiple sclerosis: A protocol for a systematic review and meta-analysis of randomized clinical trials

BACKGROUND: Multiple sclerosis (MS) is a chronic immune mediated disease which affects the central nervous system (CNS), having a substantial financial, functional, and quality of life (QOL) impact on these people. The vitamin A supplementation has been studied as a therapeutic possibility for in MS. Therefore, the objective of this protocol is to build an outline for a future systematic review, which will provide up-to-date available evidence about the clinical impact of nutritional supplementation of vitamin A in the outcomes related to the symptoms in patients with this pathology. METHODS: The search will be performed in the following databases: PubMed, Embase, Scopus, cinahl, Scielo, Web of Science, the Cochrane Library and Science Direct, randomized clinical trials published until May 2019 that evaluate the relationship of the supplementation of vitamin A and health-related outcomes in patients with MS will be included. Preferred Reporting Items for Systematic review and Meta-Analysis Protocols (PRISMA-P) will be used to outline the protocol, and PRISMA to the systematic review. Undergraduate handbook of quality of evidence and strength of recommendations for decision making in health (GRADE) will be used to assess the quality of evidence and the strength of the recommendation, and the JADAD scale to assess the internal validity of selected studies. For the extraction of all the data found a database in Microsoft Excel will be created. For the summary of the findings the Cochrane Collaboration Handbook recommendations will be used, and for the meta-analysis standard statistical techniques the RevMan software will be used. RESULTS: In this study, we hope to find a considerable number of articles presenting evidence about the effectiveness of vitamin A supplementation in patients with MS. CONCLUSION: Currently, many lines of evidence have been produced when it comes to the use of food supplements. This systematic review proposal might provide recent, important, and trusted information for better treatment of patients. RECORD OF SYSTEMATIC REVIEW: This review was recorded in the International Register of Prospective Systematic Reviews (PROSPERO) on the January 30, 2019 (registration: CRD42019121757). Available at: http://www.crd.york.ac.uk/PROSPERO/display_record.php?ID=CRD42019121757.