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Randomized Controlled Trial
. 2022 Dec 16;14(24):5346.
doi: 10.3390/nu14245346.

Drops of Capillary Blood Are Not Appropriate for Hemoglobin Measurement with Point-of-Care Devices: A Comparative Study Using Drop Capillary, Pooled Capillary, and Venous Blood Samples

Vanessa De la Cruz-Góngora  1 , Ignacio Méndez-Gómez-Humarán  2 , Elsa Berenice Gaona-Pineda  1 , Teresa Shamah-Levy  1 , Omar Dary  3
Affiliations
Randomized Controlled Trial

Drops of Capillary Blood Are Not Appropriate for Hemoglobin Measurement with Point-of-Care Devices: A Comparative Study Using Drop Capillary, Pooled Capillary, and Venous Blood Samples

Vanessa De la Cruz-Góngora et al. Nutrients. .

Abstract

Population-based surveys matched by time but using different methodologies for determining hemoglobin (Hb) concentration have shown inconsistencies in estimating anemia prevalence. This study aimed to estimate measurement errors in Hb quantification in HemoCue 201+ using venous blood (VB) and capillary blood both drops (DCB) and pools (PCB), and compare the results against those of a reference method (VB analyzed in hematology analyzers based on the cyanmethemoglobin method). Children (n = 49), adult females (n = 50), and older adults (n = 50) were randomly allocated to donate VB (4 mL) and either DCB (three drops) or PCB (350 µL). Results in HemoCue were analyzed through Bland Altman and Lyn's concordance against Hb concentration by the reference method. A positive average bias (systematic error) was found for the HemoCue (0.31 g/dL) using the same VB samples. This value was then subtracted from all readings carried out in the device. After this adjustment, DCB still produced a positive bias (0.42 ± 0.81 g/dL), and the variation of single results was ±1.6 g/dL (95% CI). PCB and VB performed similarly; the average bias was negligible (-0.02 ± 0.36 and 0.00 ± 0.33 g/dL, respectively) and the variation of the results (95% CI) was ±0.7 g/dL or lower. Lyn's concordance values were 0.86, 0.96, and 0.98 for DCB, PCB, and VB, respectively. Random variation using DCB is too large to approximate the true Hb values, and therefore DCB should be discontinued for diagnosing anemia both in individuals and in populations.

Keywords: HemoCue; anemia; capillary blood; cyanmethemoglobin; hemoglobin; venous blood.

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Conflict of interest statement

The authors declare no conflict of interest. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript; or in the decision to publish the results. OD works for USAID but acted on his personal capacity; the content of this article do not necessarily reflect the views of USAID or the United States government.

Figures

Figure 1
Figure 1
Procedures and measurements.
Figure 2
Figure 2
Correlation (a), Bland–Altman (b) and Concordance (c) plot for Hb concentrations by venous blood samples using the cyanmethemoglobin method and the HemoCounter ABX Micros 60.
Figure 3
Figure 3
Box plots of Hb difference * (g/dL) between measurement duplicate analyzed using the HemoCue 201+. * Bland–Altman Mean ± SD; (95% CI).
Figure 4
Figure 4
Bland–Altman plots of Hb concentration determined using the HemoCue in different blood sample sources versus using the cyanmethemoglobin method with venous blood. (a) Data before adjustment using the systematic bias *, (b) data after adjustment *. * The values of the HemoCue were adjusted by subtracting the average systematic bias of 0.314 g/dL estimated in the Bland–Altman plots that compared paired results of venous blood in the HemoCue and with the cyanmethemoglobin method. Abbreviations: V201 = Hb venous analyzed in Hemocue 201. VREF = Hb venous analyzed with the cyanmethemoglobin method. PC-201 = Pooled Capillary analyzed in Hemocue 201+. DC-201 = Drop Capillary analyzed in Hemocue 201+.
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