Pulse oximetry values from 33,080 participants in the Apple Heart & Movement Study

Area of Science:

• Physiology
• Biomedical Engineering
• Digital Health

Background:

• Wearable devices offer novel opportunities for large-scale physiological data collection.
• Pulse oximetry (SpO2) measurements can be obtained non-invasively.
• Understanding SpO2 variations in diverse populations is crucial for establishing health benchmarks.

Purpose of the Study:

• To analyze a large dataset of SpO2 measurements from wearable devices.
• To establish population-level reference trends for SpO2 under naturalistic conditions.
• To investigate demographic influences on SpO2 circadian patterns and trends.

Main Methods:

• Cross-sectional analysis of 72 million SpO2 values from 33,080 participants in the Apple Heart and Movement Study.
• Stratification by age, sex, BMI, home altitude, and race/ethnicity.
• Multivariate ordinary least squares regression to quantify population-level trends.

Main Results:

• SpO2 measurements exhibited consistent circadian patterns across all demographic groups, with lower saturation overnight.
• Daytime SpO2 regression coefficients aligned with laboratory-based reference models.
• Significant differences in age- and BMI-dependent SpO2 trends were observed between sexes.
• Small, statistically significant differences in daytime SpO2 were noted among racial/ethnic groups.

Conclusions:

• Wearable SpO2 devices can establish healthy population reference trends outside clinical settings.
• Circadian SpO2 patterns are robust across demographics, but age, sex, and BMI influence trends.
• Further research can refine SpO2 interpretation based on individual demographic factors.