Towards achieving even distributions of participant skin tones when verifying pulse oximeter performance

Purpose. This communication describes a a skin tone characterization methodology for the international standard ISO 80601-2-61:2026 (Ed 3) on pulse oximeter basic safety and essential performance. The methodology’s goal is to create the appropriate proportional distributions of skin tones for participants in pulse oximeters performance verification studies. We elucidate the techniques and associated metrics used for characterizing skin tone. This standard is currently in its final draft and voting stage before becoming formally adopted. Methods Various methods to quantify pigmentation were evaluated for their suitability for the purpose. Evaluation criteria included precision, accuracy, standardizability and efficacy for communication. The evaluations and selections are the result of ISO Joint Working Group activity over a period of about two years. Results The individual typology angle (ITA), was identified as a preferred objective measurement method of pigmentation. It is colorimetry based, is consequently highly standardized and has high precision and accuracy. The Monk Skin Tone scale was selected as a subjective method to complement the objective method as it is much more relatable than the ITA. Conclusion A standardized method for assessing skin tone and standardized expectation for balanced participant enrollment across the world’s range of skin tones was defined. A colorimetry based metric is used for precision and accuracy in combination with a color scale for optimal communication and recruitment.