Usefulness of Noninvasive Hemoglobin Measurement in Community-Dwelling Elderly People

Introduction The evaluation of anemia in elderly people is important; however, routine assessment using traditional blood sampling can be difficult due to its invasiveness and practical constraints. Recently, Rad-67^TM (Masimo Corp., Irvine, CA) has become available, which can measure Hb levels noninvasively using a sensor that measures absorbance, such as a SpO2 meter. However, there are some uncertainties regarding the accuracy of SpHb level measurement using this technology and whether sufficient blood flow is required for reliable measurement in elderly people. If the Hb measurement using Rad-67^TM can be applied to elderly people, it may be possible to measure the Hb of patients by medical professionals who are not qualified to draw blood, which would be clinically significant. This study aimed to clarify whether transcutaneous hemoglobin (SpHb) measurement using Rad-67^TM in elderly people is as useful as blood sampling and whether it has the ability to discriminate suspected anemia. Methods The study participants were community-dwelling elderly people aged 65 or older who participated in a survey on frailty. The assessment included measurement of hemoglobin (Hb) level using blood sampling, SpHb level measured through the finger using Rad-67^TM, room temperature, and temperature and perfusion index of the finger. Statistical analyses for each measurement outcome included (1) comparisons between males and females and across measurement conditions, (2) calculation of the correlation coefficient between Hb levels using blood sampling and SpHb levels, and (3) calculation of the cut-off value for SpHb levels using the area under the receiver operating characteristic curve and Youden's index. Results The SpHb level using Rad-67^TM was not significantly different from the Hb level using blood sampling. When the effects of room temperature, finger temperature, and perfusion index were excluded, a positive correlation was observed with the Hb level using blood sampling overall in men and in women when analyzed separately. Furthermore, the results showed that SpHb measurements may have a moderate ability to significantly discriminate between those with suspected anemia in men and in women when analyzed separately. The cut-off values of SpHb for screening for suspected anemia were < 13.5 g/dL in men and < 13.0- < 13.1 g/dL in women. Conclusion SpHb measurement using Rad-67^TM is relatively useful for understanding trends in Hb levels in elderly people and may be useful for screening for suspected anemia, using a cut-off value for SpHb measurement.