Assessing accuracy and precision of hemoglobin determination in venous, capillary pool, and single-drop capillary blood specimens using three different HemoCue® Hb models: the multi-country HEmoglobin MEasurement (HEME) study

Background Anemia prevalence estimates reported in population surveys can vary based on the blood-specimen source (capillary or venous) and analytical device (haematology auto-analyzers or portable hemoglobinometers) used for hemoglobin (Hb) determination. Methods This multi-site (Cambodia, Ethiopia, Guatemala, Lebanon, Nigeria, Tanzania) study assessed Hb measurements in paired venous and capillary blood-specimen from apparently healthy women (15–49 years) and children (12–59 months) using three HemoCue® Hb models (201+, 301, 801). Measurements were compared against reference values: venous blood in hematology automated analyzers (AA) and adjusted via regression calibration or mean-difference in HemoCue® Hb. Venous, capillary pool, and single-drop capillary blood-specimens were assessed for accuracy and precision. Findings Venous blood measured via HemoCue® Hb 301 exhibited positive mean error, while responses in HemoCue® Hb 201+ and 801 were non-directional compared with the reference. Adjustment with the reference harmonized mean errors for all devices across study-sites to <1·0 g/L using venous blood. Precision was highest for venous blood (±5 to 16 g/L) in all sites, lowest for single-drop capillary (± 9 to 37 g/L), and intermediate (± 9 to 28 g/L) for capillary pool blood-specimen. Imprecision differed across sites, especially with both capillary blood-specimens, suggesting different levels of personnel skills. Interpretation Findings suggest that venous blood is needed for accurate and precise Hb determination. Single-drop capillary blood use should be discouraged due to high measurement variability. Further research should evaluate the viability and reliability of capillary pool blood for this purpose. Accuracy of HemoCue® Hb devices can be improved via standardization against results from venous blood assessed via AA.