Date Published: February 7, 2017
Publisher: Public Library of Science
Author(s): Teresa Shamah Levy, Ignacio Méndez-Gómez-Humarán, María del Carmen Morales Ruán, Brenda Martinez Tapia, Salvador Villalpando Hernández, Mauricio Hernández Ávila, Wilbur Lam.
To evaluate the accuracy and precision of HemoCue 201 (HemoCue) and Masimo Pronto 7 (Masimo) devices for measuring hemoglobin (Hb) in epidemiological studies, having venous blood samples as a gold standard.
We measured Hb concentrations in a field sample of 148 children from one to five years of age. Masimo and HemoCue were used for capillary blood samples and an automatic analyzer for venous blood samples. Regression models with no intercept were constructed to measure precision and predictability, concordance correlations to measure accuracy and precision, and Bland-Altman limits of agreement as well as hierarchical linear models to estimate variance.
Both HemoCue and Masimo underestimated Hb concentrations compared to the gold standard. They respectively yielded the following results: regression coefficients of 0.887 and 0.876 with 98.7% and 98.6% predictability; concordance correlation coefficients of 0.183 (p<0.001) and 0.166 (p<0.001); and Bland-Altman variances of -1.51 and -1.62. With regard to Masimo specifically, the three-level Hierarchical Linear Model showed that 57.9% of total variance stemmed from random errors in repeated measures from the same subject. HemoCue and Masimo measure lower Hb concentrations than the gold standard. Their accuracy and precision levels are comparable. It is essential to ensure proper use of devices through enhanced training of field workers.
Anemia is the leading nutritional problem faced by public health worldwide. Of the 1.62 billion affected individuals, children under five years bear the heaviest burden with a prevalence of 47%. Anemia exerts a negative short-term impact on physical growth and cognitive development. In the long run, it undermines work productivity in adults with substantial economic consequences. [1, 2]
A pilot field study was conducted to validate the precision and accuracy of Hb measurement using HemoCue and Masimo in epidemiological studies. A sample size of 150 subjects was calculated to compare the HemoCue and Masimo measures with those of the gold standard, considering a confidence level of 95%, an error limit of 0.23 g/dL for mean Hb estimation and a standard deviation of 1.42 g/dL.
We excluded 11 children form the original sample because of implausible Hb values for children under five years. Table 2 shows the estimated mean of Hb concentrations by equipment for the final sample of 137 children. The means obtained with HemoCue and Masimo were significantly lower (p<0.001) than those of the gold standard (laboratory venous blood measures), with paired estimated differences amounting to -1.51 g/dL and -1.62 g/dL, respectively. Hb measures are an important determinant both in assessing anemia during fieldwork and in balancing the speed and ease of rapid analysis with the accuracy of traditional laboratory methods. The latter have long involved invasive blood draws followed by sample analysis with laboratory devices such as the CO-Oximeter. Recently, however, invasive and noninvasive Hb measurements are being performed using point-of-care devices. Source: http://doi.org/10.1371/journal.pone.0170990