Do Hemoglobin Concentration and Anemia Prevalence Differ Between Capillary and Venous Blood and Between Analysis Methods?

Abstract

Abstract Objectives Our objective was to compare hemoglobin concentration and anemia prevalence between (1) analysis methods, i.e., the portable HemoCue 201 + and the Sysmex XP-100 automated hematology analyzer, and (2) blood matrix, i.e., venous and capillary, in women and young children. Methods We collected capillary and venous blood samples from 349 non-pregnant women (NPW), 45 pregnant women (PW), and 167 children aged 6–36 months in rural Sylhet Division, Bangladesh in late 2019. We measured hemoglobin concentration in capillary and venous blood using HemoCue 201 + at the point of blood collection in the villages. In addition, hemoglobin concentration was measured in venous EDTA blood samples in the lab using the XP-100 Sysmex automated hematology analyzer within 6 hours of collection. Hemoglobin values were compared using paired t-tests, while anemia prevalence estimates were compared using McNemar tests. Results Venous hemoglobin concentrations were similar (mean difference: 0.3 g/L) when measured by HemoCue and the hematology analyzer. However, among NPW, there was strong evidence that anemia prevalence was higher when measured by HemoCue compared to the hematology analyzer, with similar trends in PW and children. Mean hemoglobin concentrations in capillary blood were lower overall (mean difference: 5 g/L; P ≤ 0.001) and in all subgroups (NPW, PW, and children) compared to venous blood. Anemia prevalence was higher in each population group using capillary (NPW: 37%; PW: 51%; children: 21%) compared to venous measures (NPW: 23%; PW: 36%; children: 10%). Conclusions Across all groups, capillary measures resulted in significantly lower hemoglobin concentrations and higher anemia prevalence estimates, thus likely overestimating anemia in the population. Venous blood samples measured by the two analytic methods were similar. This may point to a biological difference between capillary and venous blood. Funding Sources Data collection was primarily supported by the German Ministry of Education and Research (BMBF). The first author received support from the Alexander von Humboldt Foundation and a Thrasher Research Fund Early Career Award.