Devices which measure blood oxygen levels could be giving “seriously misleading” results for black and minority ethnic people, possibly contributing to increased Covid-19 mortality, experts have warned.
Pulse oximeters attach a clip-like device to a person’s finger, toe or earlobe and send a beam of light to measure oxygen levels in the blood.
The resulting SpO2 reading can be used to monitor oxygen levels of people with a variety of conditions, including by people at home with coronavirus, and to assess patients in hospital.
But a new paper cites a “growing body of evidence” that pulse oximetry is less accurate in darker skinned patients.
This could be contributing to health inequalities such as the increased Covid-19 mortality rates of ethnic minority patients, according to a review conducted for the NHS Race and Health Observatory.
It is calling for the Medicines and Healthcare products Regulatory Agency (MHRA) to urgently review pulse oximetry products for ethnic minority people used in hospitals and by the UK public.
The review, by Olamide Dada, from Cardiff University School of Medicine, cites evidence from more than three decades of inaccurate and ambiguous readings for those with darker pigmentation and skin tones.
A study in 1990 found that inaccurate pulse oximetry readings were more than two times more common in black patients than white patients.
Further trials found overestimated SpO2 levels in dark-skinned individuals with low blood oxygen levels.
And a 2020 Michigan University study found pulse oximeter readings of blood oxygen levels were three times more likely to be inaccurate among African-American patients.
The review says: “Given the increased mortality amongst ethnic minority patients during the Covid-19 pandemic, it is possible that the differential accuracy of pulse oximetry is a contributing factor to this health inequality.”
Serious clinical implications could include delays in people seeking medical care, or inadequate oxygen being provided to patients, it warns.
And it could result in intensive care patients with coronavirus receiving premature “step-down” treatment.
Dr Habib Naqvi, director of the NHS Race and Health Observatory, said: “At this pivotal time, we cannot afford to overlook this rapid review and the recommendations for action which can prevent late hospital admissions and help improve the health of black and minority ethnic people at risk or recovering from Covid-19.
“This review has stressed the need to ensure healthcare equipment and devices are culturally competent and sensitive, whilst not contributing to the array of current and historic health inequalities.”
Royal Pharmaceutical Society director for England Ravi Sharma said: “This review exposes an area of health inequality where one treatment may yield more effective results for one group of patients over another, this is not acceptable and needs to be urgently addressed.
“Pharmacists and other healthcare professionals who use pulse oximeters in their practice or provide them to the public should take ethnicity into account when considering their effectiveness in users.”
Graeme Tunbridge, MHRA director of devices, said: “The MHRA is aware of the potential impact of skin colour on pulse oximeter readings.
“Clinicians and health professionals using pulse oximeters are well aware of their function, limitations and factors affecting accuracy and do not depend entirely upon these readings, instead using them in combination with other diagnostic indicators.
“For patients being monitored at home, there is ongoing healthcare support available.”
He said the MHRA has not received any reports of adverse incidents where there is a concern over incorrect results or “any information suggesting increased risks in the BAME community relating to this factor”, but will continue to monitor this closely.
If the MHRA detects any potential safety concerns over results in a clinical setting it will “investigate thoroughly”, he added.
Healthcare professionals and members of the public can report any safety concerns through the MHRA’s yellow card scheme.