Restrospective Study Finds That Masimo SET® Pulse Oximetry Has No Difference in Accuracy or Bias Between Black People and White People
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Masimo SET® Pulse Oximetry with RD SET® Sensors (Photo: Business Wire)
A 2020 letter to the editor2 and paper3 purported to find “racial bias” in pulse oximetry measurements, based upon a comparison of data obtained from black and white patients compiled from multiple sets of health record data, using unspecified pulse oximeters and controls. Masimo Founder and CEO Joe Kiani responded to the letter and promised additional research to test Masimo’s understanding of the subject and hypothesis about the performance of Masimo technology. The first of such studies was conducted and reported by Dr. Steven J. Barker (Chief Science Officer, Masimo) and Dr. William C. Wilson (Chief Medical Officer, Masimo). Drs. Barker and Wilson performed a retrospective analysis of Masimo laboratory data obtained from black and white volunteer subjects, in an effort to identify differences in Masimo pulse oximeter accuracy and bias between ethnic groups.
The authors reviewed data collected between October 2015 and July 2021, which included 7,183 paired samples (3,201 black and 3,982 white) collected from 75 subjects (39 black and 36 white), who were screened with the same criteria to remove potential bias based on health conditions. All subjects were exposed to the same hypoxia protocol, which varied the arterial saturation of hemoglobin (SaO2) between 70% and 100%. Noninvasive oxygen saturation (SpO2) values were obtained from Masimo SET® pulse oximeters with RD SET sensors and time-matched (within 5 seconds, rather than up to 10 minutes as in the letter to the editor) with arterial blood gas (ABG) samples analyzed using an ABL-835 blood gas analyzer.
The authors analyzed the data to determine the bias (the mean difference in paired SpO2 and SaO2 samples), precision (standard deviation of the difference), and accuracy (root mean squared error, ARMS*) for both groups. They found a negative bias of 0.20% for black subjects, compared to a negative bias of 0.05% for white subjects, a difference of 0.15% (p < 0.001), which is not clinically significant and is numerically indistinguishable because the SpO2 display resolution is 1% on commercially available pulse oximeters (both from Masimo and other manufacturers). They found precision of 1.40% for black subjects and 1.35% for white subjects. Accuracy (ARMS) was 1.42% for black subjects and 1.35% for white subjects. These results are consistent with the accuracy specifications of RD SET sensors (1.5% accuracy ARMS).
By comparison to the Masimo finding of 0.15% difference in bias between black and white subjects, the 2020 letter to the editor reported a difference in bias of 8.1% in a cohort of black and white hospital patients2 – 54 times higher than the Masimo result.
Masimo is conducting additional studies and will report its findings in the future.
@Masimo | #Masimo
*ARMS accuracy is a statistical calculation of the difference between device measurements and reference measurements. Approximately two-thirds of the device measurements fell within +/- ARMS of the reference measurements in a controlled study.
Masimo (NASDAQ: MASI) is a global medical technology company that develops and produces a wide array of industry-leading monitoring technologies, including innovative measurements, sensors, patient monitors, and automation and connectivity solutions. Our mission is to improve patient outcomes and reduce the cost of care. Masimo SET® Measure-through Motion and Low Perfusion™ pulse oximetry, introduced in 1995, has been shown in over 100 independent and objective studies to outperform other pulse oximetry technologies.4 Masimo SET® has also been shown to help clinicians reduce severe retinopathy of prematurity in neonates,5 improve CCHD screening in newborns,6 and, when used for continuous monitoring with Masimo Patient SafetyNet™ in post-surgical wards, reduce rapid response team activations, ICU transfers, and costs.7-10 Masimo SET® is estimated to be used on more than 200 million patients in leading hospitals and other healthcare settings around the world,11 and is the primary pulse oximetry at 9 of the top 10 hospitals as ranked in the 2021-22 U.S. News and World Report Best Hospitals Honor Roll.12 Masimo continues to refine SET® and in 2018, announced that SpO2 accuracy on RD SET® sensors during conditions of motion has been significantly improved, providing clinicians with even greater confidence that the SpO2 values they rely on accurately reflect a patient’s physiological status. In 2005, Masimo introduced rainbow® Pulse CO-Oximetry technology, allowing noninvasive and continuous monitoring of blood constituents that previously could only be measured invasively, including total hemoglobin (SpHb®), oxygen content (SpOC™), carboxyhemoglobin (SpCO®), methemoglobin (SpMet®), Pleth Variability Index (PVi®), RPVi™ (rainbow® PVi), and Oxygen Reserve Index (ORi™). In 2013, Masimo introduced the Root® Patient Monitoring and Connectivity Platform, built from the ground up to be as flexible and expandable as possible to facilitate the addition of other Masimo and third-party monitoring technologies; key Masimo additions include Next Generation SedLine® Brain Function Monitoring, O3® Regional Oximetry, and ISA™ Capnography with NomoLine® sampling lines. Masimo’s family of continuous and spot-check monitoring Pulse CO-Oximeters® includes devices designed for use in a variety of clinical and non-clinical scenarios, including tetherless, wearable technology, such as Radius-7® and Radius PPG™, portable devices like Rad-67®, fingertip pulse oximeters like MightySat® Rx, and devices available for use both in the hospital and at home, such as Rad-97®. Masimo hospital automation and connectivity solutions are centered around the Masimo Hospital Automation™ platform, and include Iris® Gateway, iSirona™, Patient SafetyNet, Replica®, Halo ION™, UniView®, UniView :60™, and Masimo SafetyNet®. Additional information about Masimo and its products may be found at www.masimo.com. Published clinical studies on Masimo products can be found at www.masimo.com/evidence/featured-studies/feature/.
ORi and RPVi have not received FDA 510(k) clearance and are not available for sale in the United States. The use of the trademark Patient SafetyNet is under license from University HealthSystem Consortium.
- Barker SJ, Wilson WC. Accuracy of Masimo SET® Pulse Oximetry in Black and White Volunteer Subjects: A Retrospective Review. Annual Meeting of the Society of Technology in Anesthesiology. Presented Jan 15, 2022.
- Sjoding MW, et al: Racial Bias in Pulse Oximetry Measurement N Engl J Med 2020; 383 (25):2477-2478.
- Valbuena VSM, et al: Racial Bias in Pulse Oximetry Measurement Among Patients About to Undergo ECMO in 2019-2020, A retrospective Cohort Study. Chest 2021 Sep 27; S0012-3692(21)04065-4.
- Published clinical studies on pulse oximetry and the benefits of Masimo SET® can be found on our website at http://www.masimo.com. Comparative studies include independent and objective studies which are comprised of abstracts presented at scientific meetings and peer-reviewed journal articles.
- Castillo A et al. Prevention of Retinopathy of Prematurity in Preterm Infants through Changes in Clinical Practice and SpO2 Technology. Acta Paediatr. 2011 Feb;100(2):188-92.
- de-Wahl Granelli A et al. Impact of pulse oximetry screening on the detection of duct dependent congenital heart disease: a Swedish prospective screening study in 39,821 newborns. BMJ. 2009;Jan 8;338.
- Taenzer A et al. Impact of pulse oximetry surveillance on rescue events and intensive care unit transfers: a before-and-after concurrence study. Anesthesiology. 2010:112(2):282-287.
- Taenzer A et al. Postoperative Monitoring – The Dartmouth Experience. Anesthesia Patient Safety Foundation Newsletter. Spring-Summer 2012.
- McGrath S et al. Surveillance Monitoring Management for General Care Units: Strategy, Design, and Implementation. The Joint Commission Journal on Quality and Patient Safety. 2016 Jul;42(7):293-302.
- McGrath S et al. Inpatient Respiratory Arrest Associated With Sedative and Analgesic Medications: Impact of Continuous Monitoring on Patient Mortality and Severe Morbidity. J Patient Saf. 2020 14 Mar. DOI: 10.1097/PTS.0000000000000696.
- Estimate: Masimo data on file.
This press release includes forward-looking statements as defined in Section 27A of the Securities Act of 1933 and Section 21E of the Securities Exchange Act of 1934, in connection with the Private Securities Litigation Reform Act of 1995. These forward-looking statements include, among others, statements regarding the potential effectiveness of Masimo SET® and RD SET®, and Masimo’s plan to conduct additional studies on the accuracy of Masimo SET® and RD SET on black people and white people (“Additional Studies”). These forward-looking statements are based on current expectations about future events affecting us and are subject to risks and uncertainties, all of which are difficult to predict and many of which are beyond our control and could cause our actual results to differ materially and adversely from those expressed in our forward-looking statements as a result of various risk factors, including, but not limited to: risks related to our assumptions regarding the repeatability of clinical results; risks related to our belief that Masimo's unique noninvasive measurement technologies, including SET® and RD SET, contribute to positive clinical outcomes and patient safety; risks that Masimo fails to conduct Additional Studies as planned; risks that the researchers’ conclusions and findings may be inaccurate; risks related to our belief that Masimo noninvasive medical breakthroughs provide cost-effective solutions and unique advantages; risks related to COVID-19; as well as other factors discussed in the "Risk Factors" section of our most recent reports filed with the Securities and Exchange Commission ("SEC"), which may be obtained for free at the SEC's website at www.sec.gov. Although we believe that the expectations reflected in our forward-looking statements are reasonable, we do not know whether our expectations will prove correct. All forward-looking statements included in this press release are expressly qualified in their entirety by the foregoing cautionary statements. You are cautioned not to place undue reliance on these forward-looking statements, which speak only as of today's date. We do not undertake any obligation to update, amend or clarify these statements or the "Risk Factors" contained in our most recent reports filed with the SEC, whether as a result of new information, future events or otherwise, except as may be required under the applicable securities laws.