Reproducibility of the ambulatory arterial stiffness index in patients with type 1 diabetes mellitus

Objectives 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. Methods Twenty-eight patients with type 1 diabetes mellitus and no previous or present treatment with anti hypertensive 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. Results The repeatability of AASI was considerably lower than for PP as estimated by ICC (0.38 vs. 0.90). The difference between ICC(PP) and ICC(AASI) was 0.51 confidence interval (0.25-0.82). Similarly, percentage of maximal variation was 68 and 23% respectively. Conclusion 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. Blood Press Monit 15:18-22 (C) 2010 Wolters Kluwer Health vertical bar Lippincott Williams & Wilkins.