Evaluation of the Influence of Skin Phototypes on the Accuracy of a Smartwatch for Blood Pressure and Heart Rate Monitoring

Kelly Correa Baioco da Silva1, Petronio Cabral Ferreira2, Ana Leticia Gomes dos Santos3, Erica da Costa Aguiar Oliveira1, Stella Tassinari Maximo4, Christian Goncalves Sassaki3, Samuel Minucci Camargo5, silvia helena bastos de paula6, Jose L Puglisi7, Daniel Gustavo Goroso3
1Universidade de Mogi das Cruzes, 2Universidade Mogi das Cruzes, 3University of Mogi das Cruzes, 4Sao Leopoldo Mandic, 5UniversidadedeMogidasCruzes, 6Instituto de Saúde/SesSP, 7California North State University


Abstract

Wearable devices, such as smartwatches, are widely used for remote mon itoring of blood pressure (BP) and heart rate (HR). However, their reliability across different skin phototypes still requires validation, as photoplethysmog raphy (PPG) signals may be affected by skin pigmentation. This study evalu ated the correlation and agreement of systolic blood pressure (SBP), diastolic blood pressure (DBP), and heart rate (HR) measurements obtained using a Samsung Galaxy Watch4, with an Omron HEM-7320 sphygmomanometer as the reference standard. Forty-eight participants were equally distributed among Fitzpatrick skin phototypes II, III, and IV (n = 16 per group). Simultaneous measurements were performed with participants seated at rest, following a standardized protocol. Statistical analyses included Pearson correlation and Bland–Altman agreement. Strong correlations were observed between the de vices. Stratified analysis demonstrated similar performance across skin photo types, with no systematic bias associated with skin pigmentation. Overall re sults showed SBP (r = 0.957; bias = 2.417 mmHg), DBP (r = 0.972; bias = 1.000 mmHg), and HR (r = 0.919; bias = 1.896 bpm). Bland–Altman analysis confirmed good agreement, supporting the reliability of the smartwatch for re mote BP and HR monitoring across Fitzpatrick skin phototypes (Table 1).