Diagnostic accuracy of hemoglobin for iron deficiency in pregnancy: disclosing results of a cited clinical trial

• Main Authors: Cristiane C. Bresani Salvi, Maria Cynthia Braga, Malaquias Batista Filho
• Format: Article in Journal/Newspaper
• Language: English; Spanish; Portuguese
• Published: Pan American Health Organization 2014
• Subjects: Anemia ferropénica; embarazo; índices de eritrocitos; sensibilidad y especificidad; ensayo clínico; Brasil; Medicine; R; Arctic medicine. Tropical medicine; RC955-962; Public aspects of medicine; RA1-1270; Arctic
• Online Access: https://doaj.org/article/ba7df1680c63482b8ea0d4e52a006e1a

OBJECTIVE: To analyze the accuracy of hemoglobin (Hb) concentrations as a diagnostic indicator of iron deficiency in pregnant women and to measure the efficacy of oral iron therapy using Hb z-scores rather than Hb absolute values. METHODS: The sensitivity and specificity of Hb < 11.0 g/dL, and its receiver operating characteristic (ROC) curve, in the diagnosis of iron deficiency (serum ferritin (SF) < 12.0 ng/mL) were determined in 318 women in their second trimester of pregnancy who had been screened for a clinical trial conducted in 2001 in Northeast Brazil. A secondary analysis of iron therapy efficacy was carried out using data from the trial's three different treatments (60 mg of oral iron once per week (n = 46), twice per week (n = 50), and once per day (n = 44)). The mean differences between post- and pre-treatment Hb absolute values (g/dL) and z-scores (standard deviation (SD)) were calculated for the three treatment groups for study participants with and without iron deficiency. RESULTS: Hb sensitivity, specificity, and area under the ROC curve were 60.7%, 44.3%, and 0.54 respectively. Women without iron deficiency showed improvements in Hb absolute values (as in the clinical trial's overall results) but did not have improved Hb z-scores (with scores of - 0.6 SD (95% confidence interval (CI): - 0.99, - 0.28); - 0.2 SD (95% CI: - 0.47, 0.08); and - 0.1 SD (95% CI: - 0.33, 0.18) for weekly, twice-per-week, and daily iron treatment schemes respectively). In contrast, iron-deficient women treated with the intermittent schemes had reductions in both Hb absolute values and Hb z-scores, respectively: weekly = - 0.42 g/dL (95% CI: - 0.72, - 0.12) and - 1.4 SD (95% CI: - 1.74, - 0.99); twice per week = - 0.14 g/dL (95% CI: - 0.46, 0.17) and - 1.1 SD (95% CI: - 1.44, - 0.75). CONCLUSIONS: These analyses revealed that Hb concentrations were not an accurate indicator of either iron needs or iron-therapy response in pregnant women.