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. 2024 Oct 14:5:1427261.
doi: 10.3389/fgwh.2024.1427261. eCollection 2024.

Diagnostic accuracy of a non-invasive spot-check hemoglobin meter, Masimo Rad-67® pulse CO-Oximeter®, in detection of anemia in antenatal care settings in Kenya

Angela Koech  1   2   3 , Isaac Mwaniki  1 , Joseph Mutunga  1 , Moses Mukhanya  1 , Emily Mwadime  1 , Marvine Ochieng  1 , Grace Mwashigadi  1 , Hiten D Mistry  4 , Rachel Craik  4 , Peter von Dadelszen  4 , Marleen Temmerman  1   2 , Stanley Luchters  2   5   6 , Geoffrey Omuse  7 ; PRECISE Network
Collaborators, Affiliations

Diagnostic accuracy of a non-invasive spot-check hemoglobin meter, Masimo Rad-67® pulse CO-Oximeter®, in detection of anemia in antenatal care settings in Kenya

Angela Koech et al. Front Glob Womens Health. .

Abstract

Background: Point of care hemoglobin meters play key roles in increasing access to anemia screening in antenatal care especially in settings with limited access to laboratories. We aimed to determine the diagnostic accuracy of a non-invasive spot-check hemoglobin (SpHb) meter, Masimo Rad-67® Pulse CO-Oximeter®, in the diagnosis of anemia in pregnant women attending antenatal care clinics in Kilifi, Kenya.

Methods: This was a diagnostic accuracy study that retrospectively evaluated SpHb against a validated reference standard of laboratory assessed hemoglobin (Lab Hb) by a SYSMEX XN-330 automated hematology analyzer. The study was nested within a prospective pregnancy cohort study that recruited unselected pregnant women from antenatal care clinics in two public hospitals in Kilifi County, coastal Kenya. Records with both SpHb and Lab Hb were selected from pregnancy visits between May 2021 and December 2022. Linear regression and Bland-Altman analysis were performed to compare the two tests and diagnostic accuracy parameters obtained for the diagnosis of anemia.

Results: A total of 2,975 records (from 2,203 unique participants), with paired SpHb and Lab Hb were analyzed. Linear regression showed a significant but weak positive correlation, a proportional bias of 0.44 (95% CI 0.41-0.47) and a constant of 7.59 (95% CI 7.30-7.87, p < 0.001). The median bias was 1.70 g/dl, with limits of agreement of -0.80 to 4.20. SpHb tended to be higher than Lab Hb on the low hemoglobin range but lower than Lab Hb on the high hemoglobin range. The sensitivity of SpHb in detecting anemia was 18.66%. Prevalence, specificity, positive predictive value, and negative predictive values were 46.37%, 96.77%, 83.33%, and 57.92% respectively.

Conclusion: Overall, SpHb by Masimo Rad-67® Pulse CO-Oximeter® did not accurately identify pregnant women with anemia and many cases would be missed. We would not recommend its use in antenatal care settings.

Keywords: Kenya; anemia; antenatal care; diagnostic accuracy; hemoglobin; non-invasive.

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Conflict of interest statement

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. The handling editor JMA declared a past co-authorship with the author PD.

Figures

Figure 1
Figure 1
Participant flow diagram showing selection of data for analysis. *2,975 records, from 2,975 visits, from 2,203 unique study participants. SpHb- Spot-check hemoglobin concentration by Masimo Rad-67® Pulse CO-Oximeter®, Hb, haemoglobin; Lab Hb, laboratory based hemoglobin concentration by SYSMEX XN-330 automated hematology analyzer.
Figure 2
Figure 2
Distribution of hemoglobin by MASIMO(Rad-67) and by Sysmex XN-330. SpHb- Spot-check hemoglobin concentration by Masimo Rad-67® Pulse CO-Oximeter®, Lab Hb, laboratory based hemoglobin concentration by SYSMEX XN-330 automated hematology analyzer.
Figure 3
Figure 3
Scatter plots of SpHb and Lab Hb showing total allowable error and fitted values from linear regression. SpHb, spot-check hemoglobin concentration by Masimo Rad-67® Pulse CO-Oximeter®; Lab Hb, laboratory based hemoglobin concentration by SYSMEX XN-330 automated hematology analyzer; CI, confidence intervals.
Figure 4
Figure 4
Modified Bland-Altman plot of SpHb and Lab Hb showing bias and limits of agreement. SpHb, spot-check hemoglobin concentration by Masimo Rad-67® Pulse CO-Oximeter®; Lab Hb, laboratory based hemoglobin concentration by SYSMEX XN-330 automated hematology analyzer; CI, confidence intervals.
See this image and copyright information in PMC

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