Which blood cutoff value should be used for vitamin A deficiency in children aged 3-10 years? A systematic review

Context: Blood cutoff values for vitamin A deficiency in children aged 3-10 years have not been addressed in the literature. Objective: To identify blood retinol concentrations for determining severe vitamin A deficiency in children aged 3-10 years. Data Sources: The MEDLINE, Web of Science, Embase, and Scopus databases were searched. Data Extraction: Two reviewers independently extracted article data and assessed quality. Data Analysis: The hierarchical summary receiver operating characteristic models were applied for the diagnostic accuracy meta-analysis. This review is registered at PROSPERO (identifier: CRD42020149367). Results: A total of 15 articles met the eligibility criteria, and 9 were included in the diagnostic accuracy meta-analysis. The summary estimates (95%CI) were: Sensitivity, 0.39 (0.20-0.62); specificity, 0.79 (0.65-0.88); positive likelihood ratio, 1.85 (1.33-2.57); and negative likelihood ratio, 0.77 (0.60-0.99). The area under the curve of the overall analysis was 0.68 (95%CI 0.63-0.72). Conclusions: Blood retinol concentrations have low diagnostic accuracy for severe vitamin A deficiency in children aged 3-10 years. Therefore, there is unclear evidence about the preferable cutoff point for determining severe vitamin A deficiency in children in this age group.