The Impact of Skin Pigmentation on Pulse Oximetry SpO2 and Wearable Pulse Rate Accuracy: A Meta-Analysis

Background: Medicine has used photoplethysmography (PPG) with pulse oximetry devices for decades to assess blood oxygenation (SpO ₂ ) and pulse rate (PR) and this technology is now being used in consumer devices. Skin pigmentation may influence accuracy, leading to health outcomes disparities. Methods: This meta-analysis identified 23 pulse oximetry studies with 59,684 participants and 197,353 paired observations between SpO ₂ and arterial blood and 4 wearable PR studies with 176 participants and 140,771 paired observations between PR and electrocardiography. The primary objectives were to evaluate SpO ₂ and PR accuracy by skin pigmentation group by comparing SpO ₂ accuracy root-mean-square (A _rms ) values to regulatory thresholds of 3% and PR 95% Limits of Agreement (LoA) to American National Standards Institute (ANSI), Advancing Safety in Medical Technology (AAMI), and International Electrotechnical Commision (IEC) Standards of ±5bpm. The secondary objectives were to evaluate biases and clinical relevance using mean bias and 95% confidence intervals (CI). Findings: For SpO ₂ , A _rms was 3·96%, 4·71%, and 4·15% and the pooled mean bias was 0·70% (95% CI: 0·17 to 1·22), 0·27% (95% CI: -0·64 to 1·19), and 1·27% (95% CI: 0·58 to 1·95) for light, medium, and dark pigmentation, respectively. For PR, the 95% LoA were -16.02 to 13.54, -18.62 to 16·84, and -33.69 to 32.54 and the pooled mean bias was -1·24 bpm (95% CI: -5·31-2·83), -0·89 bpm (95% CI: -3·70-1·93), and -0·57 bpm (95% CI: -9·44-8·29) for light, medium, and dark pigmentation, respectively. Interpretation: The current meta-analysis suggests overall inaccurate SpO ₂ and PR measurements across all skin pigmentation groups as they exceed FDA guidance and ANSI standard thresholds. Pulse oximeters also exhibit statistically significant overestimation of SpO ₂ for light and dark skin pigmentation, but no clinically relevant bias. Wearable PR exhibits no statistically significant or clinically relevant bias.