Evaluation of the accuracy of a non-invasive hemoglobin-monitoring device in schoolchildren

Background Iron deficiency anemia (IDA) is a public health problem in children and adolescents that is characterized by reduced hemoglobin (Hb) levels. Non-invasive monitoring devices can measure Hb levels continuously without pain or discomfort; however, little is known about their accuracy in children and adolescents. This study estimated the accuracy of a non-invasive Hb monitor in this age group. Methods Participants were outpatients visiting the Tokyo Metropolitan Children's Medical Center for blood tests between January and March 2019. Hb levels were measured using both non-invasive Astrim Fit monitoring devices and invasive blood collection followed by automated analysis. Bland–Altman analysis assessed the agreement between the two measurements. Results Overall, 120 schoolchildren (9–15 years old, 51 % female) were enrolled. The non-invasive measuring device recorded Hb levels of 13.5 ± 1.6 g/dL (mean ± standard deviation [SD]), while the mean Hb level obtained from the collected blood was 13.7 ± 1.7 g/dL. Therefore, the mean difference of bias and SD of precision was 0.17 ± 1.95 g/dL. Values of lower and upper limits of agreement were −3.65 and 3.99, respectively. There was no systematic fixed or proportion bias. Fifty-nine participants (49 %) had a relative error of ± 0.10. Conclusion The Astrim Fit non-invasive Hb monitor can be used to evaluate Hb levels among schoolchildren for health promotion or research purposes because of its extremely low bias (or precision), no systematic biases (including fixed or proportion biases), and positive correlation between non-invasive monitoring and blood drawing. However, it is difficult to assess Hb levels in children and adolescents using the Astrim Fit device for diagnostic purposes.