BMJ
Pulse oximeters overestimate oxygen levels in patients with darker skin, large study finds
The EXAKT trial (NCT05481515) found that five pulse oximeters used in NHS England’s COVID Oximetry @home program consistently overestimated oxygen saturation in individuals with darker skin tones. Peripheral oxygen saturation (SpO₂) readings were, on average, 0.6–1.5 percentage points higher than paired arterial oxygen saturation (SaO₂) values. False‑negative readings were substantially more common in patients with darker skin tones, with SpO₂ values >94% despite SaO₂ ≤92% occurring up to 35 percentage points more often than in lighter‑skinned patients. Conversely, false‑positive rates were lower in individuals with darker skin.
Clinical takeaway: In patients with darker skin tones, treat normal or near‑normal SpO₂ readings with heightened caution—confirm concerning cases with arterial sampling or repeat measurements.
Source:
Martin DS, et al; EXAKT Study Investigators. (2026, January 14). BMJ. The impact of skin tone on performance of pulse oximeters used by NHS England COVID Oximetry @home scheme: measurement and diagnostic accuracy study. https://pubmed.ncbi.nlm.nih.gov/41534914/