Assessing the Discriminatory Ability of Hemoglobin Concentration to Predict Iron Stores in Cambodian Females: A Systematic Review and Individual Participant Data Meta-Analysis.

Hemoglobin concentration is commonly used as a screening tool to guide iron interventions because it can be measured more quickly and easily using point-of-care devices than other, more direct measures of iron status (e.g., ferritin). However, anemia is not always caused by iron deficiency. Therefore, we aimed to assess the discriminatory ability of hemoglobin concentration to predict iron stores in Cambodian females of reproductive age, a population where iron deficiency prevalence is low and genetic hemoglobinopathies are common. We conducted a systematic review and individual participant data (IPD) meta-analysis that included 26 studies reporting on 11 databases (including n = 3497 females with available and eligible IPD that included hemoglobin, ferritin, and ≥1 inflammation biomarker measured in the same individual at the same time point). Receiver operating characteristic curve analyses were conducted to measure the area under the curve (AUC) and the 95% confidence interval (CI), representing the discriminatory ability of hemoglobin concentration to distinguish between individuals with or without iron deficiency (inflammation-adjusted ferritin <15 μg/L for nonpregnant females; unadjusted ferritin <30 μg/L for pregnant females). Random-effects models were used to estimate pooled effect sizes and 95% CIs. The pooled AUC value (95% CI) for nonpregnant females (9 studies; n = 3377) displayed "fair" discriminatory ability [0.77 (0.74, 0.79)] with high certainty evidence, and for pregnant females (2 studies; n = 120) displayed "poor" discriminatory ability [0.57 (0.47, 0.68)] with low certainty evidence. We conclude that hemoglobin is a "fair" predictor of iron status in nonpregnant Cambodian females; thus, it should be used with caution in guiding interventions such as blanket iron supplementation programs. More research is needed to understand if hemoglobin is an acceptable screening biomarker to guide interventions or justify higher doses of supplemental iron during pregnancy. The protocol was registered in PROSPERO (CRD42024578023).