Purpose: To study arterial stiffness in CKD by AASI compared to Augmentation Index (AIx) and aortic pulse wave velocity (aPWV). To study the intra-patient reproducibility of AASI in CKD.

Methods: Patients were studied 2 days within 2 weeks. Double applanation tonometry recordings of the radial pressure wave form and aPWV and 24-h ambulatory blood pressure measurements were done. AASI was calculated as 1 minus the regression slope of diastolic over systolic blood pressure. CKD stage was determined by estimated glomerular filtration rate. Spearman’s correlation coefficient (SCC) was used for evaluating correlations. Day-to-day reproducibility was evaluated by the intra-class correlation coefficient (ICC).

Results: 68 patients (M50:F18), median age 63 years (range 30–79), with CKD stage 2 (n=17), stage 3 (n=22), stage 4 (n=20) and stage 5 (n=9) were studied. Mean(±SD) AASI was 0.44±0.15, mean AIx was 28.2%±10.4% and mean aPWV was 9.4m/s±1.0m/s with no significant differences among the stages. The SCC between AASI and AIx was 0.320 (P=0.01), between AASI and aPWV it was 0.643 (P<0.0001) and between AIX and aPWV it was 0.346 (P=0.006). ICC_AASI was 0.755 (95% CI: 0.630–0.841) with even greater reproducibility in CKD stages 4–5 (ICC>0.860).

Conclusions: The observed values of AASI in CKD patients were similar to those reported for the background population, while AIx and aPWV were higher. Despite good correlations between these parameters, the normal values of AASI found in the present study preclude its use as an index of vascular stiffness in CKD. Intra-patient reproducibility of AASI in CKD stage 2–5 was high.