The Equity Gap in Medical Device Performance

Medical devices that rely on optical sensing—such as pulse oximeters—measure physiological signals by analyzing light as it passes through or reflects from the skin. However, studies have shown that skin tone can significantly impact measurement accuracy, particularly for individuals with darker pigmentation. 

When research participants do not represent the full spectrum of human skin tones, devices risk disparate bias—producing less reliable results for underrepresented groups. This is not just a technical issue; it’s a matter of health equity. 

Quantifying Skin Tone: From Subjective to Standardized 

Historically, skin tone in research was often recorded using vague descriptors, such as “light” or “dark,” leaving room for inconsistency. To address this, new tools like the Monk Skin Tone Scale—developed by Google Research in collaboration with Dr. Ellis Monk, a Harvard sociologist—offer a scientifically validated, 10-shade scale designed for inclusivity and cross-industry use. 

The Open Oximetry Project, founded at UCSF’s Center for Health Equity in Surgery and Anesthesia and the UCSF Hypoxia Lab, takes this further by combining standardized color charts, digital spectrophotometer measurements, and the Monk Scale to create precise, reproducible skin color quantification methods for device validation. 

By moving from subjective impressions to measurable, reproducible metrics, researchers can ensure accurate representation across the entire skin tone continuum. 

PRL’s Commitment to Inclusive Device Validation 

At Parameters Research Laboratory (PRL), skin tone diversity is built into our study design from the start. Our approach includes: 

• Targeted Recruitment Across the Monk Scale – Ensuring balanced participant representation from shade 1 to shade 10. 

• Optical Bias Detection – Evaluating device performance differences across skin tones and reporting findings transparently. 

• Standards-Driven Protocols – Integrating ISO 80601-2-61 and GCP compliance with inclusivity goals. 

We apply these principles in controlled desaturation hypoxia studies, blood pressure validation studies under ISO 81060-2 and ISO 81060-7, and other physiological monitoring research. These efforts produce regulator-ready datasets that reflect real-world populations. 

The Benefits of Inclusive Skin Tone Research 

Incorporating skin tone diversity in medical device research leads to: 

• More accurate performance across demographics 

• Reduced regulatory risk by proactively addressing disparate bias 

• Improved patient and physician trust and adoption of new technologies 

• Better alignment with global health equity initiatives 

Partnering for a More Equitable Future 

Parameters Research Laboratory’s application of Open Oximetry Project standards reflects our belief that scientific rigor and social responsibility must go hand in hand. By combining advanced laboratory testing with inclusive recruitment strategies, we help device developers ensure their innovations work for everyone, everywhere. 

Contact PRL to learn how our inclusive clinical research studies can strengthen your device’s performance, equity, and regulatory success. 

The Monk Skin Tone Scale is a 10-shade scale developed to better represent human skin tones, aiming to improve inclusivity in technology and computer vision applications

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