Diagnostic accuracy of reticulocyte haemoglobin content in detecting iron deficiency without anaemia in blood donors: A systematic review and meta‐analysis

Background and Objectives Iron deficiency without anaemia (IDWA) is a significant concern among blood donors. Reticulocyte haemoglobin content (RHC) has been increasingly investigated as an alternative biomarker to evaluate iron status, but its diagnostic performance remains unclear. We aim to assess the diagnostic accuracy of RHC for detecting iron deficiency in non‐anaemic blood donors. Materials and Methods PubMed, Embase, Scopus, Web of Science, Cochrane Library, ProQuest Dissertations & Theses, trial registries and reference lists were searched. Study quality was assessed using the Revised Tool for Quality Assessment of Diagnostic Accuracy Studies (QUADAS‐2), and the certainty of evidence was assessed using the Grading of Recommendations, Assessment, Development and Evaluation (GRADE) approach. The pooled sensitivity, specificity, likelihood ratios (LRs) and summary receiver operating characteristic area under the curve (SROC AUC ) were estimated. Results Thirteen studies involving 5853 donors were included. The pooled sensitivity, specificity, positive LR (LR+) and negative LR (LR−) of RHC to evaluate iron deficiency compared to tests using ferritin, soluble transferrin receptor or a combination of parameters were 0.70 (95% confidence interval [CI]: 0.60–0.79), 0.85 (95% CI: 0.74–0.92), 4.84 (95% CI: 2.59–9.04) and 0.35 (95% CI: 0.25–0.48), respectively; the SROC AUC was 0.79 (95% CI: 0.71–0.85). The certainty of evidence was rated as very low to low. Conclusion Evidence from this review is insufficient to support the widespread use of RHC as a standalone screening test for IDWA in blood donors. Further studies are needed to improve RHC‐based screening strategies.