The ambulatory arterial stiffness index (AASI) has been proposed as a novel indirect measure of arterial stiffness. We compared the repeatability of AASI and pulse pressure (PP), another marker of arterial stiffness, both computed from repeat 24-h ambulatory blood pressure recordings in patients with type 1 diabetes mellitus.
Twenty-eight patients with type 1 diabetes mellitus and no previous or present treatment with antihypertensive drugs were recruited from outpatient clinics in Aarhus County and underwent two 24-h ambulatory blood pressure measurements, performed within 2 weeks in all participants except one. The repeatability of AASI and PP was assessed by (i) the Intraclass Correlation Coefficient (ICC) and (ii) the percentage of maximal variation, i.e. two times SD of the difference in the percentage of four times the SD of the mean of the paired measurements.
The repeatability of AASI was considerably lower than for PP as estimated by ICC (0.38 vs. 0.90). The difference between ICCPP and ICCAASI was 0.51 confidence interval (0.25–0.82). Similarly, percentage of maximal variation was 68 and 23% respectively.
AASI has a low repeatability compared with PP in type 1 diabetic patients. This questions the potential implementation of AASI in the daily clinic as a measure of arterial stiffness. Further studies are necessary to clarify this.