Reproducibility of peripheral arterial tonometry for the assessment of endothelial function in adults

Objectives Endothelial dysfunction is associated to cardiovascular risk factors and predicts cardiovascular events. Peripheral arterial tonometry (PAT) is a novel noninvasive method to assess endothelial function. However, there is a paucity of data about its reproducibility. The aim of this study was to assess the feasibility and reproducibility of PAT in adults. Methods PAT exams were performed twice in the same day in 123 participants of a cohort about the determinants of diabetes and cardiovascular diseases (Brazilian Longitudinal Study of Adult Health--ELSA-Brasil). The interval between the exams was 2-6 h (mean=4 h). Endothelial function in PAT method is measured by reactive hyperemia index (RHI), which evaluates arterial pulsatile volume changes in response to hyperemia. Agreement of RHI values was compared by Bland-Altman method, coefficient of variation and coefficient of repeatability. Reliability was assessed by intraclass correlation coefficient (ICC). Results Mean values of RHI did not differ significantly between the exams of each participant (1.92±0.56 vs. 1.96±0.58, P=0.48). There were no systematic errors between the exams (mean of differences=-0.03±0.5). Measurement error was 0.35, coefficient of variation was 18.0% and ICC was 0.61. Sex, age or the presence of obesity did not have a considerable influence on the reproducibility of PAT. Conclusion PAT exam is feasible and has acceptable reproducibility in adults when compared with other noninvasive methods for endothelial function assessment. This performance makes PAT a promising method for future clinical and epidemiological studies.