Test‐retest reliability of peripheral arterial tonometry (PAT): Implications for trial design in cardiovascular nutrition research

Abstract

Vascular endothelial dysfunction (ED) is an important step in the development of atherosclerosis and many foods and nutrients have been shown to improve ED. However, early measurement techniques were either invasive (requiring catheterization), or highly variable and operator dependent (e.g. FMD via ultrasound). Peripheral arterial tonometry (Endo‐PAT, Itamar, Israel) has been proposed as an alternative for assessing ED in clinical trials, particularly those with multiple sites. Few studies have assessed repeatability of PAT measures, and little published information is available to guide sample size calculations. In a sample of 20 healthy adults, we measured reactive hyperemia index (RHI, a purported measure of ED) during identical tests conducted 1 week apart. Participants consumed a standardized, low antioxidant diet for 48 hours prior. As the patient reclined, a blood pressure cuff was placed on the forearm and finger‐tip pulse amplitude was measured before, during, and after 5 min cuff inflation. Paired measurements were significantly correlated (r = 0.68). The coefficient of variation was 12.2 and the interclass correlation was 0.74. We confirmed that RHI scores can be reproducibly measured under controlled conditions. Our presentation will examine the meaning of these findings for statistical power and clinical study design.The study was supported by NIH Grant M01 RR 10732.Grant Funding Source: NIH Grant M01 RR 10732