How medicine discriminates against non-white people and women

AT THE PEAK of the coronavirus epidemic in America, hospitals needed to triage patients. Only the sickest were admitted. Others were sent home to self-monitor. One measure used to determine the severity of an individual’s illness was his blood-oxygen level. The devices typically employed to do this, known as pulse oximeters, are easy to use. They clip onto a fingertip like a clothes peg. Regrettably, they record some darker-skinned patients as being healthier than they really are. This may have resulted in people who needed hospital treatment being denied it.

Work published last year in the New England Journal of Medicine, which looked at more than 10,000 patients throughout America, suggested the pulse oximeters used overestimated blood-oxygen saturation more frequently in black people than white. A healthy human being has an oxygen saturation of 92-96%. In this work some patients who registered that level according to pulse oximetry had a true saturation (as recorded by the arterial blood-gas measure, a method which requires the actual drawing of blood) of less than 88%. For black participants this happened 12% of the time—three times the rate at which it occurred for white participants. As Michael Sjoding of the University of Michigan, the study’s leader, observes, this difference would also be the difference between being admitted to the hospital and being sent home.