Reproducibility of carotid-femoral pulse wave velocity in end-stage renal disease patients: methodological considerations

Abstract

Background: In end-stage renal disease (ESRD) patients, increased arterial stiffness detected by carotid-femoral pulse wave velocity (cf-PWV) is associated with fatal cardiovascular events and all-cause mortality. Since cf-PWV is an operator-dependent technique, poor reproducibility may be a source of bias in the estimation of arterial stiffness.

Objectives: We assessed the week-to-week reproducibility of cf-PWV and radial artery pulse wave analysis in healthy subjects and ESRD patients. We also determined the extent of patient eligibility, enrollment, acceptance, and comfort.

Methods: In a cohort study design, independent tonometric examinations of carotid, femoral, and radial arteries were conducted in 20 healthy subjects and 15 ESRD patients attending chronic hemodialysis treatments according to a randomized sequence by two operators on 2 days scheduled 1-week apart. cf-PWV, augmentation index (AIx@HR75) and central pulse pressure (CPP) were the outcome measures. Patients were tested at mid-week and prior to dialysis treatment. The variability on the distance measured between the suprasternal notch and femoral site using two different methods (standard vs direct) was compared. A post-examination survey assessed acceptance and comfort associated with examinations. Reproducibility was evaluated by intra-class correlations (ICCs).

Results: The mean age for healthy subjects and ESRD patients was 45 ± 12 and 63 ± 16 years, respectively. ESRD patients had higher cf-PWV (p = 0.0002), elevated AIx@HR75 (p = 0.003), and increased CPP (p = 0.001) compared to healthy subjects. The mean inter-visit differences for all stiffness indices were non-significant (p > 0.05), but the mean inter-operator differences for the cf-PWV were significant only in the healthy subject group (-0.7 m/s; p = 0.02). The ICCs between operators and visits were higher for the ESRD group compared to the healthy subjects (between operators, 0.870 vs 0.461; between visits, 0.830 vs 0.570). Distances were longer (p < 0.001), but less variable with the standard method compared to the direct method (healthy subjects, p = 0.036; ESRD, p = 0.39). There was a high rate of patient acceptance and minimal discomfort.

Conclusions: Week-to-week measurements of cf-PWV and pulse wave analysis are highly reproducible in ESRD patients prior to hemodialysis treatment. The high reproducibility and minimal test-to-test variations encourage use of cf-PWV to monitor changes in arterial stiffness and the efficacy of interventions in ESRD patients.

Trial registration: ClinicalTrials.gov, NCT02196610.

Keywords: Aortic stiffness; End-stage kidney disease; Inter-observer variation; Validation studies.

Figures

Fig. 1

Flow chart of screening and enrollment procedure in end-stage renal disease patients. Fifty-three percent (70/131) of the original screened patients remained eligible; 16 of the 22 patients who consented completed the full study. Atrial fibrillation and presence of bilateral arteriovenous fistulas accounted for 59 % of exclusions. AVF arteriovenous fistula, BMI body mass index, ESRD end-stage renal disease